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Journal of Consulting and Clinical Psychology
2003, Vol. 71, No. 3, 504 –515
Copyright 2003 by the American Psychological Association, Inc.
0022-006X/03/$12.00 DOI: 10.1037/0022-006X.71.3.504
This document is copyrighted by the American Psychological Association or one of its allied publishers.
This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Treatment of Parental Stress to Enhance Therapeutic Change Among
Children Referred for Aggressive and Antisocial Behavior
Alan E. Kazdin
Moira K. Whitley
Yale University School of Medicine
Yale University
This study evaluated a parent problem-solving (PPS) intervention designed to augment the effects of
evidence-based therapy for children referred to treatment for aggressive and antisocial behavior. All
children (N ⫽ 127, ages 6 –14 years) and their families received problem-solving skills training (PSST),
and parents received parent management training (PMT). Families were randomly assigned to receive or
not to receive an additional component (PPS) that addressed parental stress over the course of treatment.
Children improved with treatment; the PPS intervention enhanced therapeutic change for children and
parents and reduced the barriers that parents experienced during treatment. The implications of the
findings for improving evidence-based treatment as well as the limitations of adding components to
treatment are detailed.
improve and maintain treatment gains over the course of follow-up
(e.g., Dadds & McHugh, 1992; Dumas & Wahler, 1983; Kazdin,
1995a; Wahler & Afton, 1980; Webster-Stratton, 1985). Consequently, contextual factors or the processes through which they
operate may need to be addressed to optimize the impact of
A dilemma for developing effective treatment is that many of
the contextual factors associated with conduct problems come as a
“package.” Where ought and can the therapist intervene to attenuate the deleterious impact of these factors on treatment? Stress of
the parent may be a reasonable place to begin. Stress has many
facets and definitions. In relation to the contextual factors noted
previously, it is useful to consider stress as both the events and
reactions to them that are disruptive, that alter biological and
psychosocial functioning, and that place individuals at risk for
untoward mental and physical health outcomes (Miller, 1989).
Among families of aggressive and antisocial children, stress of the
parent is intertwined with the development and maintenance of
aggressive and oppositional child behavior. Stress of the parent
influences parent disciplinary practices (e.g., commands to the
child, inadvertent or unwitting reinforcement of aversive child
behavior, and coercive interchanges) that directly promote and
escalate aggressive and oppositional child behavior (e.g., Patterson, Reid, & Dishion, 1992; Sanders, Dadds, & Bor, 1989). More
specifically, stress appears to increase parent irritability and attention to deviant behavior and the likelihood that parents initiate or
maintain aversive interchanges with their children or counterattack
in response to child aggression (e.g., Patterson, 1988; Patterson &
Forgatch, 1990; Wahler & Dumas, 1989). On the basis of such
findings, including his own set of elegant studies, Patterson (1988)
concluded that, “Therapy must help the parents [of aggressive/
antisocial children] cope with their out-of-control children and
with their own out-of-control crises at the same time, for crises and
antisocial families seem intimately related” (pp. 261–262). The
interrelations of stress, discipline practices, and deviant child behavior have yet to be exploited in developing effective treatments.
Aggressive and antisocial child behavior includes fighting, theft,
vandalism, fire setting, lying, truancy, running away, and other
acts that violate social rules and expectations. A persistent pattern
of these behaviors, referred to as conduct disorder, is associated
with impairment in multiple domains of functioning (e.g., academic performance, sibling and peer relations). The significance of
conduct disorder is underscored by its relatively high prevalence
rate (e.g., 2%– 6% of the population), the dominance of these
behaviors as a basis for clinical referral (33%–50% of the cases of
school-age children), and the poor long-term prognosis in relation
to mental and physical health outcomes and social adjustment
(Kazdin, 1995b; Robins, 1991). This significance is exacerbated
by findings that meeting the criteria for a diagnosis of conduct
disorder is not a special threshold; children close to but below that
cutoff (subsyndromal cases) have poor prognoses and untoward
outcomes as well (see Offord et al., 1992).
Providing treatment to children and families is a major challenge because aggressive and antisocial child behavior is often
embedded in a broader context of parent and family factors that
can contribute to and exacerbate deviant child behavior. For example, socioeconomic disadvantage, social isolation, poor living
conditions, interpersonal conflict and violence among family
members, parent psychopathology, high levels of stress, and lack
of social support are often associated with child conduct problems
(Maughan, 2001; Stoff, Breiling, & Maser, 1997). These contextual factors influence whether families remain in treatment and, for
those who do remain, whether and the extent to which children
Alan E. Kazdin, Child Study Center, Yale University School of Medicine; Moira K. Whitley, Child Conduct Clinic, Yale University.
Completion of research was facilitated by support from the Leon Lowenstein Foundation, the William T. Grant Foundation Grant 98 –1872–98,
and the National Institute of Mental Health Grant MH59029.
Correspondence concerning this article should be addressed to Alan E.
Kazdin, Child Study Center, Yale University School of Medicine, P.O. Box
207900, New Haven, Connecticut 06520-7900.
This document is copyrighted by the American Psychological Association or one of its allied publishers.
This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
The relation of parental stress, parent behavior, and child behavior problems extends well beyond conduct problems of children (Deater-Deckard, 1998). For example, stress and coping of
the parents predict subsequent externalizing and internalizing
problems among children and adolescents in community samples
(Takeuchi, Williams, & Adair, 1991) as well as among special
populations, including children with serious medical conditions
(e.g., brain injury, diabetes; Holmes, Yu, & Frentz, 1999; Kinsella,
Ong, Murtagh, Prior, & Sawyer, 1999) and children who have
recently immigrated (e.g., Short & Johnston, 1997). The role of
stress in interpersonal interaction also extends beyond the confines
of parenting. For example, stress experienced by institutional staff
influences staff-client interactions (among clients with developmental disabilities). Greater stress of the staff member is associated with fewer positive staff– client interactions and less caretaking activity (Lawson & O’Brien, 1994; Rose, Jones, & Fletcher,
1998b). Beyond correlational data, researchers have reported that
directly intervening to reduce staff stress increases positive staff–
client interactions (Rose, Jones, & Fletcher, 1998a). In short,
different lines of evidence suggest that stress of a caregiver influences interpersonal interactions in ways that promote deviant
A final reason to consider targeting parental stress might be the
role of stress in relation to other contextual factors associated with
conduct problems. Stress may be the final common pathway of
many contextual influences associated with socioeconomic disadvantage, single-parent family, social isolation, poor living conditions, and conflict with a partner. Also, of the many contextual
factors that co-occur among families of aggressive and antisocial
children, stress or the perception of stress is malleable, at least in
principle. One might be able to provide interventions that alter
stress experienced by the parent. Alleviating stress in one’s life or
developing coping skills is more feasible within the constraints of
providing treatment services than it is in altering socioeconomic
disadvantage, poor living conditions, and so on.
Although the case can be made for focusing on parental stress as
part of the treatment, there are reasons for tempered optimism
about the impact such a focus may exert. First, stress is only one
of multiple contextual factors that are likely to be present. When
evaluated separately, the individual contextual factors often exert
a reliable but small role (e.g., effect size) in predicting conduct
problems, participation in treatment, or therapeutic change. It is
true that the accumulation of the individual factors exerts a much
larger influence (Ackerman, Schoff, Levinson, Youngstrom, &
Izard, 1999; Deater-Deckard, Dodge, Bates, & Pettit, 1998; Kazdin, 1995a; Kazdin & Wassell, 1999). Yet, this raises the prospect
that the focus on any single component such as stress may not
necessarily have a palpable influence on treatment.
Second, stress as a predictor of either child deviance or therapeutic change may be explained by other influences. For example,
socioeconomic status and income often are strongly (and inversely) related to stress experienced by parents (Kazdin, Stolar, &
Marciano, 1995; Lindblad-Goldberg, Dukes, & Lasley, 1988;
Sanders et al. 1989). If stress is merely a proxy for other variables
(e.g., socioeconomic disadvantage), it is unlikely that reducing
parental stress would have much impact on treatment outcome.
Third, stress experienced by the parent decreases with effective
treatment of aggressive and antisocial children, even if parental
stress is not focused on directly (Kazdin & Wassell, 2000). That is,
as child deviance declines, parent stress decreases. Any further
effort to change parental stress beyond the changes that occur
anyway might not make a sufficient incremental difference to
influence treatment outcome.
Stress can be defined and measured in many different ways
(e.g., S. Cohen, Kessler, & Gordon, 1997; Miller, 1989). (Indeed,
just reading about the options made the authors quite nervous,
irritable, pressured, and less able to sleep than usual.) Our work
has focused on perceived stress on the part of the parent (i.e.,
perceptions and the experience that parents report at the outset and
over the course of treatment). Perceived stress is readily distinguishable from life events and contributes separately to child
outcomes (e.g., Takeuchi et al., 1991). For example, perceived
stress at the beginning of treatment influences participation in
treatment (e.g., attendance, dropping out prematurely, and child
progress) and child treatment outcome (Kazdin & Mazurick, 1994;
Kazdin & Wassell, 1999). This effect cannot be explained by other
contextual influences (e.g., socioeconomic factors, living conditions, parent psychopathology) or by life events and specific stressors that occur either prior to or over the course of treatment.
Noting that perceived stress (or any other variable) predicts
treatment outcome and barriers that families experience during
therapy does not necessarily mean that this variable is an appropriate target for intervention (Kraemer, Stice, Kazdin, Offord, &
Kupfer, 2001). However, research reviewed earlier indicated that
stress plays a pivotal role in the day-to-day parenting and deviance
of antisocial children, in the behavioral problems of children
without identifiable disorders, and in how institutional staff interact with their clients. These findings are promising in suggesting
stress may be an appropriate target for treatment (Deater-Deckard,
1998; Patterson, 1988). A strong test of whether parent stress
influences outcome is direct intervention to reduce stress and
evaluate the outcomes of interest.
This study consisted of a randomized controlled trial to evaluate
a component of treatment designed to reduce parent stress. Parental stress is related to multiple facets of treatment (e.g., outcome,
participation in treatment). Consequently, we predicted that intervening to alter stress would have broad impact and, specifically,
would improve treatment outcomes, reduce the extent to which
parents experienced barriers in coming to treatment, and improve
treatment attendance. Treatment outcome referred to therapeutic
change in three areas: child symptoms and functioning, parent
psychopathology and stress, and family relations. Although the
priority of child treatment is improvement in the problems for
which the child was referred, treatment of the child can have
positive outcomes on parent and family functioning as well (Kazdin & Wassell, 2000). We have argued that these concomitant
outcomes of child therapy may be important in their own right
insofar as the changes (e.g., reduced parent depression and stress,
improved family relations) are intertwined with child mental
health and family quality of life (e.g., Crowley & Kazdin, 1998).
Barriers to treatment refer to perceived demands and problems
associated with participating in treatment. Parents who perceive
barriers during the course of treatment are more likely to cancel
and not show up for sessions; also, their children show less
therapeutic change (Kazdin, Holland, & Crowley, 1997; Kazdin,
Holland, Crowley, & Breton, 1997). Third, treatment attendance
consists of canceling and not showing up for treatment, a significant problem in delivering services to children and families (Ka-
This document is copyrighted by the American Psychological Association or one of its allied publishers.
This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
zdin, 1996a). Attendance is likely to be less consistent among
parents who are high in stress. Attendance raises service delivery
issues (e.g., cost of unused treatment slots when families fail to
attend). Also, at some point, checkered or inconsistent treatment
attendance is likely to attenuate the benefits of treatment, hence it
is a pertinent domain of interest in relation to therapeutic change.
We conducted a treatment trial for children and families referred
for outpatient treatment of aggressive and antisocial behavior. All
children and families in this study received the same evidencebased treatment, as described later. The families differed on
whether they received an additional component of treatment designed to address stress of the parent. Consecutive referrals of
children were randomly assigned to receive or not to receive this
latter intervention.
Participation was initiated by families who contacted a triage center at a
child psychiatry service that serves a large catchment area or who directly
contacted the clinic. Children referred for oppositional, aggressive, antisocial behavior were seen at the Yale Child Conduct Clinic, an outpatient
treatment service for children and families. After referral, children and
families completed an initial evaluation to assess child, parent, and family
functioning and then began treatment. Informed consent was solicited and
obtained from all families, including the parent(s) or primary caretaker and
all children more than 7 years of age. The sample included consecutive
children who completed treatment. The study included 127 children (27
girls and 100 boys) and families. Sample size (⬎ 50 participants per group)
was greater than usually used in treatment outcome studies because two
active (and effective) interventions were compared. Effect sizes for such
comparisons tend to be in the small-to-medium range (e.g., .4 –.5) and are
not likely to be detected with sample sizes in the usual range (n ⬍ 20 per
group; Kazdin & Bass, 1989; Rossi, 1990). The study included only
children who completed treatment, given the focus on pre- and posttreatment. This excluded 34.2% of the children who dropped out before
completing treatment. This attrition rate is in keeping with the 40%– 60%
for child, adolescent, and adult therapy (Kazdin, 1996a). The drop-out rates
for the two treatment groups described later were no different, ␹2(1, N ⫽
194) ⫽ 1.13, ns. Dropouts, when compared with completers, were slightly
older (10.4 vs. 9.8 years old, t[192] ⫽ 2.50, p ⫽ .01), had lower Wechsler
Intelligence Scale for Children—Revised (WISC–R; Wechsler, 1974) intelligence quotient (IQ) scores (94.9 vs. 103.3, t[192] ⫽ 3.44, p ⬍ .001),
were from lower socioeconomic status (37.7 vs. 40.8 family Hollingshead
score, t[192] ⫽ 2.52, p ⫽ .01), and showed more symptoms of conduct
disorder on the diagnostic interview (4.4 vs. 3.0). Dropouts and completers
were no different in the number of comorbid diagnoses, number of symptoms across all other diagnoses other than conduct disorder or overall
severity of symptoms (Child Behavior Checklist; CBCL; Achenbach,
1991), proportion of boys and girls, or subject and demographic variables,
with one exception. More dropouts were from minority (African American,
Hispanic American, biracial) families than from European American families, ␹2(1, N ⫽ 194) ⫽ 8.53, p ⬍ .01. Our prior work has suggested
minority group differences are accounted for by the association of ethnic
identity in this clinic population with lower socioeconomic status (Kazdin
et al., 1995). Overall, the characteristics of dropouts and completers are in
keeping with other outcome studies with children referred for aggressive
and antisocial behavior (Kazdin, 1996a). In separate reports, we have
detailed characteristics of dropouts and therapeutic changes they evince
(Kazdin, Mazurick, & Siegel, 1994; Kazdin, Holland, & Crowley, 1997).
Children ranged in age from 6 to 14 years (M ⫽ 9.8, SD ⫽ 1.8); 88
(69.3%) of the children were European American, 27 (21.3%) were African
American, 6 (4.7%) were Hispanic American, 2 (1.6%) were Asian American, and 4 (3.1%) were biracial, based on parent identification of ethnicity.
Diagnoses of the children were obtained from the Research Diagnostic
Interview (Kazdin, Siegel, & Bass, 1992), a structured interview of the
parents that assessed the presence, absence, and duration of child symptoms, based on the Diagnostic and Statistical Manual of Mental Disorders
(3rd ed., rev.; DSM–III–R; American Psychiatric Association, 1987). Reliability of Axis I diagnoses was routinely assessed by independent observers for 10%–15% of randomly selected children over the period in
which this project was conducted and yielded high agreement (␬ ⫽ .95
across all diagnoses).
Children were included on the basis of referral for aggressive and
antisocial behavior as the primary presenting clinical problem. A psychiatric diagnosis of conduct disorder was not required for inclusion because
evidence suggests that impairment, the need for treatment, and long-term
deleterious outcomes characterize children who fall below the threshold for
meeting criteria for the diagnosis (Offord et al., 1992). Principal Axis I
diagnoses were conduct disorder (29.9% of the children), oppositional
defiant disorder (40.2%), attention– deficit/hyperactivity disorder (3.1%),
major depressive disorder (9.4%), other disorders (12.6%), or no diagnosable Axis I disorder (4.7%). Across primary and secondary diagnoses, the
most common diagnosis was conduct disorder (42.5% of the children).
Most children (77.2%) met criteria for more than one disorder (M ⫽ 2.4
disorders, SD ⫽ 1.2). The most common comorbid diagnoses were conduct
disorder with attention– deficit/hyperactivity disorder and oppositional defiant disorder with attention– deficit/hyperactivity disorder (each for 29.9%
of the sample). Full-scale WISC–R IQ scores ranged from 56 to 144 (M ⫽
103.3, SD ⫽ 15.9); 5 of the cases were below an IQ of 70, one of the
DSM–IV (4th ed.; American Psychiatric Association, 1994) criteria for
mental retardation. (All cases were retained and the findings did not change
with or without these cases.)
The primary caretakers of the children included biological (90.6%) or
adoptive mothers (7.1%) or other relatives (2.4%), who ranged in age
from 24 to 55 years (M ⫽ 36.4, SD ⫽ 6.3); 37.0% of the children came
from single-parent families. Family occupational and educational level
(Hollingshead, 1975) was distributed from lower to higher sociooccupational classes as follows: Class I ⫽ 5.5%, Class II ⫽ 14.2%, Class
III ⫽ 25.2%, Class IV ⫽ 37.8%, and Class V ⫽ 17.3%. Median monthly
family income was $2,001 to $2,500 (range: $0 –$500 to ⬎ $5,000); 18.1%
of the families received social assistance.
Measures were completed before and after treatment and drew on varied
assessment formats (interviews, questionnaires, direct observations) and
informants (parents and therapists). The therapist responsible for the case
administered pretest measures at intake to obtain pertinent background and
diagnostic information. At the end of treatment, research assistants rather
than the therapists administered posttreatment outcome measures to the
parents to avoid inadvertent influences or expectations that the presence of
the therapist might promote. Immediately prior to treatment, parents completed a General Information Form to assess participant, demographic, and
family characteristics, in addition to the diagnostic interview, mentioned
previously. Additional assessments focused on parent stress and the three
domains predicted to reflect intervention effects.
Perceived parental stress. At the beginning and end of treatment,
parents completed the Parenting Stress Index (PSI; Abidin, 1990; Lloyd &
Abidin, 1985). The 120 items, each rated on a 5-point scale, reflect
multiple areas of stress related to the parents’ views of their own functioning. The measure was selected because it assesses perceived sources of
stress, delineates perceived stress from life events, and distinguishes
sources of stress from the child (e.g., subscales such as Adaptability,
Demandingness, and Child Mood) and sources of stress related to the
parent functioning (e.g., subscales such as Restrictions of Role, Social
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Isolation, and Relations With Others). The focus of our intervention was
primarily on parents’ views of how stress related to their own functioning.
However, sources of perceived stress are related. Hence, child, parent, and
total perceived stress scores were used in this study. Diverse types of
reliability (internal consistency, test–retest) and validity (concurrent, predictive) for the PSI have been reported in the measure references.
Treatment outcome. To evaluate treatment outcome, we administered
measures before and after treatment. Three outcome domains of interest
were changes in the children, parents, and family, each assessed with
multiple measures. The measures to represent these domains were based on
prior work attesting to their validity, lack of redundancy within a domain,
and ability to discriminate among treatments (Kazdin & Wassell, 1999,
2000). Therapeutic changes of the children were evaluated with three
measures that focused on child symptoms and dysfunction. First, parents
completed the Interview for Antisocial Behavior (IAB; Kazdin & EsveldtDawson, 1986; Kazdin et al., 1992), a semistructured interview that measures multiple overt (e.g., fighting) and covert (e.g., lying) antisocial
behaviors of the child. This measure reflects primary symptoms for which
children are referred to the clinic. Each of the 30 items is rated on a 5-point
scale for severity of dysfunction (1 ⫽ not a problem at all, 5 ⫽ very much
a problem) and a 3-point scale for duration (1 ⫽ recent or new problem [ 6
months], 3 ⫽ always). Total antisocial behavior is obtained by summing
severity and duration scores, in keeping with scoring of the IAB in studies
of the validity of the scale. Internal consistency and construct validity have
been supported in studies noted previously.
Second, at the beginning of treatment, parents were interviewed to
identify oppositional, aggressive, and antisocial child behaviors that occurred at home in the past week. The interview included a list of 23
behaviors that served as a pretreatment index of problems for the Parent
Daily Report (PDR; Chamberlain & Reid, 1987). At the end of treatment,
parents observed behavior at home for 10 days within a 2–3 week period
to assess the daily occurrence of each of the 23 behaviors (i.e., whether
each occurred within the past 24 hr). The mean daily total number of
behaviors observed by the parent served as the measure of child problems
in the home. The PDR shows adequate internal consistency, test–retest
reliability, and interrater agreement, and correlates with overt behavior
recorded by observers in the home (Foster & Robin, 1997).
Finally, to assess a broad range of symptoms, parents completed the
CBCL. This measure includes 118 items (each rated on a 0- to 2-point
scale) that comprise multiple behavior problems. The total problem score
was evaluated to assess severity of dysfunction across a broad range of
symptom domains. The measure is especially relevant to the present
sample because of the high rates of comorbid disorders and symptoms
spanning multiple diagnoses. Various forms of reliability and validity of
the CBCL have been studied extensively in clinic and nonclinic samples.
Therapeutic changes of the parent were assessed by three measures that
focused on parent psychopathology and perceived stress. First, parents
completed the Beck Depression Inventory (BDI; Beck, Steer, & Garbin,
1988). For each of 21 items, the parent selected one of three statements that
differed in the presence or severity of the symptom. Second, to sample a
broader range of symptoms, parents completed the Hopkins Symptom
Checklist (SCL-90; Derogatis & Cleary, 1977). The scale included 90
items, rated on a 5-point scale, to reflect the degree of discomfort across
several symptom areas. The total score was used as an overall index of
psychiatric dysfunction of the parent. The psychometric properties of the
BDI and SCL-90 have been studied extensively. Third, parent perceptions
of stress were assessed by the PSI. We used the total score from the PSI.
(In some analyses, stress on the PSI is evaluated separately from therapeutic change to evaluate whether stress was influenced specifically by the
intervention designed to reduce stress.)
Therapeutic changes in the family were assessed with three measures
that focused on relationships and resources within the family. Two measures were drawn from the Family Environment Scale (FES; Moos &
Moos, 1981) completed by the parents. The FES includes 90 items (true–
false) that assess quality of interpersonal relationships, support, structure,
and functioning of the family. Two second-order factors were used from
the scale to assess quality of family relationships (cohesion, expressiveness, conflict) and system maintenance (organization and functioning of
the family as a system). The FES has been studied extensively, and diverse
types of reliability and validity have been demonstrated. The third measure,
completed by the parents, was the Sense of Support Scale (SSS; Aneshensel & Stone, 1982), and it assessed perceived social support. Parents
reported how often within the past 2 months they received support in their
daily lives (e.g., someone was thoughtful when they were tired, provided
emotional support, or helped with problems). Seven items or opportunities
to receive support were rated on a 5-point scale (1 ⫽ all of the time, 5 ⫽
never). Total perceived support is based on the sum of all items. The
psychometric properties of the SSS have not been extensively evaluated.
The scale was selected because it has reflected changes in parents over
treatment in our prior research and because of the brevity of the scale in the
context of a large assessment battery.
Barriers to participation in treatment. Parents often experience barriers that are directly related to participation in treatment and these barriers
influence therapeutic change of the child. Parents completed the Barriers to
Treatment Participation Scale (BTPS; Kazdin, Holland, & Crowley, 1997;
Kazdin, Holland, Crowley, & Breton, 1997).1 The BTPS is an interview
that consists of 44 items rated on a 5-point scale (1 ⫽ never a problem, 5 ⫽
very often a problem). The items compose four themes: (a) stressors and
obstacles that interfere with participating in and coming to treatment (e.g.,
conflict with a significant other about treatment, problems with other
children that interfered with treatment), (b) treatment demands and issues
(e.g., concerns the treatment and the extent to which treatment was confusing, difficult, or demanding), (c) perceived relevance of treatment (e.g.,
whether treatment was seen as relevant to the child’s problems and met
with parent expectations), and (d) relationship with the therapist (e.g.,
parent’s alliance and bonding with the therapist). Data on the internal
consistency, interrater agreement, subscales, and convergent and discriminant validity have been provided in the previously cited references. At the
end of treatment, parents and therapists independently completed the BTPS
to provide separate sources and perspectives about barriers experienced by
the parent.
Treatment attendance. Two measures of participation in treatment
consisted of canceling sessions and not showing up for treatment. Canceling sessions referred to occurrences when the parents or family member
called the clinic in advance of a session to say that they could not attend.
An answering machine was always available for those times in which the
clinic was closed (after hours, weekends) so that calls could be received at
any time. Missed treatments referred to participants not appearing for a
session without calling in advance. Canceling and not showing up were
coded routinely on a master schedule each day by someone unaware of the
study or hypotheses. The number of cancellations and no-shows for a given
family are partially confounded by how long a person is in treatment (i.e.,
greater time in treatment could lead to more missed appointments). Consequently, cancellations and no-shows were divided by the number of
weeks in treatment to provide cancel and no-show rates per week. Cancellations and no-shows relate to perceived barriers (i.e., greater barriers
are associated with poorer treatment attendance; Kazdin, Holland, Crowley, & Breton, 1997).
Treatment provided to all families. After intake assessment, children
and families began treatment. All families received an evidence-based
treatment that consisted of the combination of cognitive problem-solving
skills training (PSST) provided to the child and parent management train-
A copy of the Barriers to Treatment Participation Scale can be obtained
from Alan E. Kazdin.
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This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
ing (PMT) provided to the parents (Kazdin, 1996b). Prior research has
indicated that PSST and PMT, alone or combined, lead to change and are
more effective than waiting-list, no-treatment, and minimal-treatment control conditions and other interventions such as relationship therapy (Brestan & Eyberg, 1998; Kazdin, 2000b; Sheldrick, Kendall, & Heimberg,
2001).2 Although each of these treatments separately produces therapeutic
change and qualifies as an evidence-based treatment, the combination tends
to be more effective (Kazdin, 1996b; Webster-Stratton & Hammond,
In PSST, children were seen individually for approximately 20 –25
sessions and learned problem-solving skills (e.g., generating alternative
solutions, means– ends thinking) to manage interpersonal situations (e.g.,
with parents, teachers, siblings, and peers). Within the sessions, problemsolving skills were developed through practice, modeling, role-playing,
corrective feedback, and social and token reinforcement. Outside of the
sessions, the children applied problem-solving steps to interpersonal situations in everyday life. In PMT, parents saw therapists individually for
approximately 16 sessions to develop adaptive parenting practices and
child–parent interaction patterns and to alter child behavior at home and at
school. Practice, feedback, and shaping were used to develop parental skills
in the sessions and specific behavior-change programs for use outside of
the sessions. Child functioning at school was incorporated into treatment
through contact with the teacher and home-based reinforcement programs.
Each treatment included a core set of sessions to convey content, themes,
and skills. Within the core sessions, child domains of dysfunction at home
and at school and special family circumstances (e.g., living conditions, job
schedules, custody issues, use of extended family members) were individualized. Occasionally, additional sessions were provided to address specific problems or a theme that was not sufficiently well conveyed in the
core session. For each treatment, parents were brought into the child
sessions and/or the child was brought into the parent session. The goals of
these sessions were to review that part of treatment that was carried out at
home and to role-play and practice under supervision (feedback, shaping,
praise) of the therapist.
Treatment provided to some families. Families were randomly assigned at intake to receive an additional component of treatment referred to
as parent problem solving (PPS). Although assignment to conditions was
random, a slightly greater percentage of cases was allocated in advance to
be assigned to PPS rather than the no-PPS condition (55% vs. 45%). Our
pilot work suggested potential gains for the families that received PPS,
hence we provided this to slightly more than half of the families, as
determined on an a priori basis. Although statistical power is maximized
when group size is equal, the small difference in sample sizes for the two
groups provided a potentially helpful procedure (PPS) to more families
without any palpable loss of power.
PPS consisted of five sessions interspersed over the course of treatment,
approximately every 2 to 4 weeks. In the initial session, the therapist
explained the nature of treatment and conducted an interview about stressors in the parent’s life. These stressors asked the parent to comment on
problems at work, finances, marriage and relationships, involvement with
social agencies (e.g., family services), extended family, medical issues and
conditions, and other areas the parent identified. Also, the interview ended
with a focus on what might make life more enjoyable (e.g., more time with
a partner, time for oneself). During these sessions the therapist and parent
met to develop problem-solving skills in the parent and to focus on using
these skills to address stressors of the parent in everyday life. The focus of
PPS is on one parent (usually the mother) in two-parent families or the
person who has primary care responsibilities for the child.3 (PMT is
provided to both parents, as available; PPS is reserved for only one parent.)
The rationale for this focus was drawn from prior research on the role
stress, isolation, and insularity of the mother or primary caretaker plays in
relation to child deviance and untoward parent– child interaction (Patterson, 1988; Wahler, 1980).
During the PPS sessions the parent was trained to identify alternative
solutions to stressful problems and to select and attempt concrete solutions
as part of treatment. For many stressors (e.g., living with HIV, deplorable
living conditions, loss of a partner), there may not be “solutions,” hence the
focus was on helping the parent develop coping strategies and use resources (e.g., friends, work, activities) to participate in life in ways that the
person would see as helping. Each PPS session focused on a single area or
theme (e.g., relationship with one’s partner). The themes were devised by
reviewing with the parent in the initial session potential sources of stress
and having him or her rate severity in a semistructured interview that part
of this initial session. Each session, approximately 50 min, comprised three
phases. The first phase was information gathering, in which the therapist
queried to identify the situation, context, circumstances, and details about
the source of stress. The second phase focused on cognitions (attributions,
beliefs about the problem) and affect (feelings about different facets of the
problem). The goal was to identify the impact of the situation on the
parent’s thoughts and feelings. In the third phase, problem solving was
approached more concretely either to alter aspects of the situation or to
develop coping methods. The parent was encouraged to discuss different
solutions or alternatives (problem solve) to address a facet of the problem.
Concrete ideas (alternative solutions) were carefully weighed and evaluated (solutions and consequences). Plans (means– ends thinking) were
spelled out in very specific terms and structured in a manageable stepwise
fashion. During this phase, the therapist used prompts (e.g., modeling,
instructions), shaping, and social reinforcement to foster use of a problemsolving approach and to generate concrete, realistic solutions that could be
Typically, one to three solutions were selected as a homework assignment and mutually agreed to by the therapist and parent. The parent played
the more central role in selecting the solutions to ensure the solutions
addressed critical facets about the situation, pertained to how the parent felt
and thought about the situation, and were feasible to carry out in light of
practical considerations (e.g., demands of parenting or work). Some of the
homework assignments required special behaviors or behaviors that the
parent may have considered difficult (e.g., asking a partner to care for the
children one night, speaking to a relative, or talking to a coworker).
Role-play, modeling, and practice were used to help the parent, as needed.
The therapist and parent alternated roles in practicing what to say and what
reactions might be evident in the other person. Role-playing, shaping,
feedback, praise, and practice, central to PMT, were used in the role-play
to develop parent behavior as needed in PPS. Execution of the homework
assignment was evaluated by phone contacts during the week and reviewed
at the beginning of the next session.
Themes addressed in PPS were stressors the parent identified as part of
assessment at the beginning of treatment. The most common themes were
having more time with one’s partner, having more time for oneself,
job-related stress, and finances. Major psychopathology (e.g., bipolar disorder, substance abuse) and stressful problems such as marital discord in
which marital and legal counseling were required were not treated. The
parent was referred for treatment, as was true of all clients at the clinic
whether or not they were involved in PPS. Although five PPS sessions
were planned, occasionally optional sessions were provided if a homework
assignment could not be carried out or if the theme required further
immediate attention after a PPS session.
Comparison of the different treatments is beyond the scope of this
study and has been addressed elsewhere (see Kazdin, 1996b).
PPS was piloted for a period of 18 months. As part of this, we
attempted to administer the intervention to both parents together. This did
not prove to be feasible or productive primarily because venting of marital
issues, blaming of child deviance, and comments of one parent often
dominated the session.
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Therapists and treatment administration. Fifteen clinicians (3 men
and 12 women, ages 23–56, all European American) served as therapists.
Therapists had a master’s degree (n ⫽ 13) or doctoral degree (n ⫽ 2) from
programs in clinical psychology, social work, or another mental healthrelated field. The therapists participated in a 6 –12 month training program
to learn the treatments. Training involved extensive role-playing and modeling to master treatment. After initial training, training cases were assigned. These cases were closely supervised using direct observation,
review of tapes, and discussion of the case on a session-by-session basis.
Throughout the study, treatment sessions continued to be taped for supervision and review.
Treatment integrity. To maintain integrity of treatment, we used the
following steps: (a) therapists followed a treatment manual that delineated
the content and focus of each session; (b) materials were provided to foster
correct execution of the treatment, including checklists that prescribed the
necessary materials (e.g., charts, games for each session, the specific
themes and tasks to be covered) and notes and outlines for use within the
sessions; (c) documentation of the session summarized what transpired and
how the child or parent progressed; (d) ongoing clinical supervision was
provided through direct observation of live treatment sessions with television monitors connected to cameras in the treatment rooms; (e) all treatment sessions were videotaped, and some of them were reviewed weekly
to provide feedback to the therapists; and (f) all cases were reviewed
weekly to identify the current status of treatment, including what transpired
in the previous session, what was planned in the upcoming session, and
whether there were any special issues that would influence treatment
delivery. These procedures were designed to maintain treatment integrity.
No quantitative measure of treatment integrity was obtained in this study.
In our program, we have assessed treatment integrity by randomly audiotaping sessions and having naive raters score the extent to which treatmentspecific activities for the sessions were engaged in or completed, including
review of the programs or child activity (e.g., for PMT and PSST) in the
home, presentation of the new material for that session, practice and
role-play of activities, therapist use of praise, and other tasks. The only
“lapses” of treatment integrity are not completing all of the tasks because
of time constraints (e.g., parent has come in late and the session cannot be
completed; review and repair of the program required the entire sessions).
These are not lapses, but they serve as a basis for providing optional
sessions if a session has not been completed.
Preliminary Analyses
Changes from pre- to posttreatment. The study tested whether
PPS influenced therapeutic change, perceived barriers to treatment
participation, and treatment attendance. Among these three domains, only therapeutic change included pre- and posttreatment
assessment. Preliminary analyses were completed to identify
whether children, parents, and families improved over the course
of treatment. The means for pre- and posttreatment performance on
the child, parent, and family outcome measures are presented in
Table 1 for both groups combined. Within-group t tests indicated
that children improved over the course of treatment, as reflected by
reductions in total antisocial behavior (IAB), specific problem
behaviors observed at home (PDR), and total symptoms (CBCL
total Behavioral Problems score). Parent and family functioning
also improved over the course of treatment as reflected in reductions in parental depression (BDI), a broader range of symptoms
(SCL–90), improved relationships and system organization (FES),
and social support in the home (SSS). Overall, within-group improvements were evident for both groups in each domain; this is in
keeping with prior work on children and families that receive
Changes in stress. The PPS intervention was intended to reduce parental stress, hence one would expect greater reductions in
parenting stress as a function of treatment condition. To evaluate
stress, we evaluated measures of the PSI (as noted in Table 1) with
a multivariate analysis of variance involving Condition (two dif-
Table 1
Measures of Treatment Outcome: Means, Standard Deviations, and Within-Group Changes
(t tests) for Treatment Groups Combined
Parenting Stress Index (PSI)
PSI Parenting subscale
PSI Child subscale
PSI total
Child outcome measures
Interview Antisocial Behavior
Parent Daily Report
CBCL total behavior problems
Parent outcome measures
Beck Depression Inventory
Symptom Checklist-90
Family outcome measures
Family Relationships
Family System
Social Support
Note. Improvements in child and parent measures are based on reduction of scores (e.g., lower symptoms)
whereas improvements on family measures reflect an increase in scores (e.g., improved relationships, support).
The signs of the t tests for the family measures were reversed so that all tests in the table reflect improvement.
CBCL ⫽ Child Behavior Checklist.
* p ⱕ .05. *** p ⱕ .001.
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ferent treatments) ⫻ Time (pretreatment, posttreatment). The multivariate effect of primary interest from the analyses is the Condition ⫻ Time interaction that conveys whether groups differed at
posttreatment. The results indicated that this effect was not statistically significant, F(3, 123) ⫽ 1.76, ns, Wilks’s ␭ ⫽ .96. There
was a significant time effect, F(3, 123) ⫽ 39.57, p ⬍ .001, Wilks’s
␭ ⫽ .51, and no condition effect, F(3, 123) ⬍ 1.0. The effect of
time is in keeping with our prior work, which shows that parent
stress decreases over the course of child treatment as the child
improves regardless of whether the special parenting stress intervention (PPS) was provided.
The focus of the PPS intervention was on parenting stress. If one
examines the Parenting subscale of the PSI that more specifically
addresses the focus of treatment, the PPS and no-PPS intervention
groups differ as predicted. Specifically, the PPS group showed a
significantly greater reduction in parenting stress than did the
non-PPS group, t(125) ⫽ 2.08, p ⬍ .05. Overall, our primary
conclusion from the analyses is that stress changes over the course
of treatment. This is the most marked effect in this study and in our
prior work. One could argue whether the PPS intervention was
shown to lead to greater reduction in stress than the no-PPS
condition. Our one t test on a subscale of parenting stress is not
persuasive in this regard. Moreover, one wonders whether an
interaction effect (Condition ⫻ Time) can be easily shown because
of the statistically robust effect due to time. Further analyses of the
role of stress and therapeutic change are presented later.
Magnitude of therapeutic changes. We were interested in a
summary score for child, parent, and family outcomes to provide
an overall index of change, to estimate the magnitude of improvements in each domain, to examine the relations of changes across
domains, and to test the effects of PPS. A therapeutic index of
change was calculated separately for child, parent, and family
outcome measures on the basis of combining measures within each
domain. For each child, a z change score was derived for each
measure (IAB, PDR, CBCL) by subtracting the posttreatment from
the pretreatment raw score and dividing by the pretreatment standard deviation. This yielded a z score that reflected how much
change was made relative to the pretreatment distribution of
scores. This z score placed each outcome measure on the same
metric. The mean of these three scores provided an overall z score
and a summary index of improvement for the children. A mean z
score was also computed for the parent measures and family
measures from pre- to posttreatment in the same way.
The indices of change for children, parents, and families, as
expressed as z scores, are equivalent to effect size (i.e., pre ⫺
posttreatment/standard deviation unit). Small, medium, and large
effect size estimates, calculated as .20, .50, and .80 (J. Cohen,
1988), can be used as reference points to evaluate the impact of
treatment. For both treatment conditions combined (PPS and no
PPS), child, parent, and family mean z scores were 1.36 (95%
confidence interval [CI] ⫽ 1.23, 1.49), 0.38 (95%
CI ⫽ 0.29, 0.48), and 0.28 (95% CI ⫽ 0.17, 0.38), respectively.
The child therapeutic changes correspond to a large effect size;
parent and family changes correspond to small-to-medium effect
Impact of PPS
The central question guiding the study was whether focusing on
PPS and stress would have beneficial effects on three domains:
treatment outcome, barriers parents experienced over the course of
treatment, and treatment attendance. To compare the two treatment
conditions, we completed multivariate analyses (Hotelling’s T2)
separately for each domain.
Therapeutic outcome for children, parents, and families. A
multivariate analysis of child, parent, and family indices of therapeutic change indicated a significant overall effect, T2(3,
122) ⫽ 4.54, p ⬍ .01. Therapeutic change was significantly greater
among families that received PPS. In addition to the overall
domain, we were interested separately in the child, parent, and
family outcomes. Table 2 presents the mean z scores separately for
the two treatment groups. For the group that received PPS, child,
parent, and family mean z scores were 1.50 (95% CI
⫽ 1.33, 1.68), 0.50 (95% CI ⫽ 0.36, 0.64), and 0.28 (95%
CI ⫽ 0.13, 0.44), respectively. For the group that did not receive
PPS, child, parent, and family mean z scores were 1.19 (95%
CI ⫽ 1.01, 1.37), 0.25 (95% CI ⫽ 0.13, 0.36), and 0.27 (95% CI
⫽ 0.11, 0.42).
We were interested in indexes of change for child, parent, and
family domains. To evaluate whether treatment conditions differed
Table 2
Comparison of Treatments With and Without Parent Problem Solving (PPS)
Therapeutic change
Child Change Index
Parent Change Index
Family Change Index
Barriers to treatment
BTPS (Parent report)
BTPS (Therapist report)
Treatment attendance
Not showing up
Effect size d
Note. BTPS ⫽ Barriers to Treatment Participation Scale.
* p ⱕ .05. ** p ⱕ .01. *** p ⱕ .001.
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in outcome effects, we conducted multivariate analyses (Condition ⫻ Time) separately for child, parent, and family domains, as
these domains and constituent measures are noted in Table 1. The
multivariate effect of interest from the analyses is the Condition ⫻
Time interaction, which conveys whether groups differed at posttreatment. Results of the multivariate analyses indicated that at
posttreatment, the PPS intervention group showed greater change
in child outcome measures, F(3, 114) ⫽ 4.38, p ⬍ .001, Wilks’s
␭ ⫽ .91, and parent outcome measures, F(3, 114) ⫽ 3.82, p ⬍ .01,
Wilks’s ␭ ⫽ .93, but no differences in family outcome measures,
F(3, 121) ⫽ 1.26, ns, Wilks’s ␭ ⫽ .97. Thus, children whose
parents received PPS, compared with those who did not, showed
less severe antisocial behavior, fewer problem behaviors at home,
and fewer overall symptoms. Similarly, parent outcome of treatment was better for parents who received PPS, as reflected in a
greater reduction in parent depression, overall symptoms, and
stress. The two treatment conditions indicated no differences on
the family outcome domain (t ⬍ 1.0). Other effects from the
multivariate analyses indicated no group differences at pretreatment (group effect) and overall changes from pretreatment (time
effect) in keeping with other analyses. The analyses of treatment
outcome provide partial support for the hypothesis. Children,
parents, and families improved over the course of treatment. The
gains in child and parent outcome measures were significantly
greater among families that received PPS.
Overall, the prediction that targeting parental stress with an
added treatment component would improve therapeutic change
was supported. Supplementary analyses indicated that the effects
of PPS did not vary as a function of child age, gender, ethnicity,
therapist, or child diagnosis alone or in combination (interaction)
with PPS. Also, initial level of parent stress did not influence
(moderate) treatment. That is, the effects of PPS were equal among
families that varied in initial levels of stress.
Barriers to participation in treatment. Parents and therapists
independently completed the BTPS to measure barriers to participation in treatment. A multivariate analyses of two measures as a
function of treatment condition yielded a significant effect, T2 (2,
117) ⫽ 4.59, p ⬍ .01. Overall, parents who received PPS experienced fewer barriers to participation in treatment than parents who
did not receive PPS. The t tests in Table 2 convey that barriers
were significantly lower on both the parent-completed and
therapist-completed measures. Effect sizes were in the small-tomedium range (d ⫽ .35 and .50, respectively).
Treatment attendance. A multivariate analyses of two measures of treatment attendance (rates of cancelled and no-show
sessions) as a function of treatment condition yielded no significant overall effect, T2(2, 124) ⬍ 1, ns. We peeked at the univariate
tests (but only for a second), which indicated group means for
either measure were not different and would not even allow us to
use the inappropriate term “approached significance” (please see
Table 2).
Supplementary Analyses
This study was not designed to identify the mechanisms through
which the intervention achieved change, a topic to which we return
in the Discussion. Even so, further analyses can shed light on
possible explanations of the findings. First, the superior effects of
PPS might be due to a relatively straightforward interpretation
related to the dose of treatment. Families that received PPS received approximately five more sessions of treatment. Perhaps
duration of treatment and additional therapy time with families
would explain why PPS families fared better in treatment. Extra
sessions might provide benefits because of more social support
provided by the therapist or by spreading PMT out over a longer
period. However, amount of time in treatment was not consistently
related to therapeutic change among children, parents, and families, as reflected in correlations of .20 ( p ⬍ .05), .04 (ns), and .01
(ns), respectively. In short, more treatment is not a highly plausible
explanation of the present results.
Second, parent stress served as the guiding construct and focus
of PPS. Is change in stress on the part of the parent a plausible
explanation for the benefits of that intervention? (Actually, we
were hoping the reader would not ask this.) Testing this requires
assessment of processes and proposed mediators during the course
of treatment, which was not part of the design of this study
(Kazdin, 2003). Also, our prior work has shown that parental stress
decreases markedly as the child improves in treatment, even without focusing on parent stress during treatment. With such a strong
effect, an additional effort to demonstrate changes in stress specific
to the PPS group and changes in stress in relation to outcome
domains would have methodological (assessment, power)
Mentioned previously was the finding that the PPS group
showed significantly greater reductions in parenting stress (PSI
subscale) over the course of treatment than the no-PPS group. The
correlations between reductions in parenting stress and improvements in treatment for child, parent, and family (n ⫽ 69) indices of
change were .12 (ns), .31 ( p ⬍ .01), and .32 ( p ⬍ .01), respectively. A more direct test of the possibility that stress reduction
accounts for the changes can be achieved with procedures described by Holmbeck (2002). The procedures allow for post hoc
probing of significant mediational effects, including direct and
indirect effects and whether the mediator effect meets criterion for
statistical significance. Using these techniques, we did not show
that parenting stress met criteria for a mediational effect in relation
to child, parent, or family therapeutic change. The results do not
support stress as a mediator of the benefits of the PPS treatment.
In this study, all children received PSST and all parents received
PMT. Improvements were evident among children, parents, and
families whether or not they received the added component of PPS.
For families who also received PPS, there were greater therapeutic
changes and reduced barriers to participation in treatment. The
incremental benefits of PPS are noteworthy because the core
treatment (PSST ⫹ PMT) produces relatively potent changes
(Sheldrick et al., 2001). The addition of an intervention that
focused on the parents made a difference nonetheless.
Given that this study was a randomized controlled trial, it is
parsimonious and plausible to conclude that the intervention was
responsible for the differences between groups (i.e., that there was
a causal relation between the intervention and the outcomes of
interest). A randomized controlled trial is not a final step in the
process of understanding change and, indeed, in the case of the
present research is actually an early step. The reason pertains to the
notion of construct validity (Cook & Campbell, 1979). Specifi-
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cally, although it is reasonable to attribute the effects to “the
intervention,” that facet of the intervention or why the intervention
led to the differences is not clear. Effective treatments— even very
well investigated treatments— often are shown and known to produce change without evidence that the putative processes involved
account for the change. An excellent example is cognitive therapy
for depression, in which the proposed reasons for the effectiveness
of treatment (e.g., changes in specific cognitions) have not been
established as mediators of outcome (Burns & Spangler, 2001;
Hollon & Beck, 1994; Kazdin, 2003). In a parallel way, this study
conveys that the intervention is likely to be responsible for change,
but without a demonstration of why or through what processes.
As noted previously, stress is one of many factors that often
co-occur among families of children with conduct problems and
that influence treatment outcome. The usual research strategy by
which this influence is established is measurement of multiple risk
factors and statistical evaluation of their separate, combined, and
incremental contributions to a particular outcome (e.g., onset of
disorder, relapse, therapeutic change). We have taken this strategy
in some of our prior work (Kazdin, 1995a; Kazdin et al., 1995). In
this report, we elected a complementary strategy, namely, to select
a construct (parental stress) that (a) has been implicated in prior
research as pivotal to the clinical problem (e.g., the interrelation of
parent stress, disciplinary practices, and deviant child behavior),
(b) has been shown to relate to child treatment outcome, and (c) is
malleable (i.e., it can change and be changed within the confines
of an intervention study). These criteria helped us to sift through
many variables (e.g., socioeconomic status, life events, living
conditions, poor neighborhoods, parent history of antisocial behavior) relevant to treatment outcome and led us to parental stress.
Also, we have seen parental stress change in response to treatment
of aggressive and antisocial children (Kazdin & Wassell, 2000).
Thus, stress is likely to be reciprocally related to child deviance
(i.e., it contributes to but also is influenced by deviant child
Although the study indicated that PPS led to significant changes,
many constructs other than stress might be proposed to explain the
findings. Indeed, it is incumbent on us to look elsewhere because
mediational tests did not suggest stress was the critical influence.
Changes in parent depression, self-esteem, and empowerment and
improved marital relations sometimes are concomitant effects of
effectively treating children with externalizing problems (e.g.,
Scovern et al., 1980; Taub, Tighe, & Burchard, 2001). Moreover,
parental stress is intertwined with depression and absence of social
support in families of children with conduct problems (Patterson &
Forgatch, 1990; Wahler & Dumas, 1989). Perhaps our PPS intervention achieved change by altering one of these other facets, and
stress played an indirect role.
As an alternative interpretation, perhaps PPS exerted its effect
by improving patient adherence to the core treatments. PSST and
PMT make demands on families (e.g., setting up reinforcement
programs in the home, engaging in problem-solving skills homework assignments included as part of the child’s treatment). PPS
may serve a motivational function by improving how well parents
carry out the procedures. In support of this, attention to parental
concerns and family issues in the context of treating disruptive
children improves parent attendance and retention in treatment
(Prinz & Miller, 1994; Santisteban et al., 1996). It is only a small
leap to propose that other facets of complying with treatment (e.g.,
executing behavior-change programs at home) are enhanced by
PPS and account for the present results. Indeed, many families of
aggressive and antisocial children are quite stressed, and reduction
of stress may be essential to execution of any treatment procedure.
The present study was not designed to elaborate the mechanism
of change. Rather, our first goal was to evaluate whether an added
intervention to an evidence-based treatment could lead to reliable
changes and to do so across multiple domains. The next priorities
would be to replicate the effect and test alternative interpretations
to explain any changes PPS produces.
Parent training, a core part of our intervention, is the most
well-investigated treatment for oppositional, aggressive, and antisocial children (Brestan & Eyberg, 1998; Kazdin, 2000a). In the
context of treatment and prevention, several studies have supplemented parent training with problem-solving interventions directed toward the children (e.g., Kazdin, 1996b; Webster-Stratton,
1996) and social support and problem solving of the parent (e.g.,
Dadds & McHugh, 1992; Pfiffner, Jouriles, Brown, Etscheidt, &
Kelly, 1990; Sanders, Markie-Dadds, Tully, & Bor, 2000). The
results indicate that treatment effects can be enhanced with additional interventions. Our results are in keeping with these other
studies. Clearly, the upcoming tasks are better triage, that is,
matching children and families to identify who requires or profits
from such treatments and of course the mechanisms through which
adjunctive interventions effect change.
Several limitations of this study deserve mention. First, this
study focused on children clinically referred for aggressive and
antisocial behavior. Parent stress may well play a role in diverse
clinical problems for which children are referred. However, there
is reason to be cautious about generalization of the present findings
to other clinical populations, given the special role that stress has
been shown to play in disciplinary practices, child deviance, and
treatment outcome among children referred for aggressive and
antisocial behavior. That research served as a critical impetus for
our focus on parental stress.
Second, perception of parent stress was assessed with a single
measure. There is a danger in generalizing beyond any one measure of a construct, even one as well investigated as the PSI.
Replication of the present study with different ways to operationalize perception of stress would be quite valuable. Our study was
restricted to one measure to capture the facet of perceived stress
that has emerged as critical to treatment in our prior research. Yet,
there is such a broad range of measures of stress and hassles and
the perception and experience of each of these as to provide many
research leads for further study.
Third, and related, the measures were restricted to parent report
as the source of information regarding therapeutic change. Different measures were used including observations of concrete behaviors parents observed in the home (PDR). Even so, this too can be
conceived as parent report. The perspectives of others pertinent to
therapeutic change (children, teachers, clinicians) and different
assessment modalities (e.g., records of fights, school detentions)
were not included. The generality of results across informants and
modalities of assessments remains to be shown.
Fourth, our PPS intervention was provided in the context of an
effective, evidence-based treatment. We cannot state and do not
even propose that PPS would be effective on its own (without the
other treatments) or as an adjunct to another treatment. PPS was
developed after years of work with highly stressed families of
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referred aggressive and antisocial children. PPS addresses one
facet of a larger child–parent–family-context gestalt specific to
conduct problems (Kazdin, 1995b).
Fifth, we did not quantify treatment integrity. The supervision
procedures in place are no substitute for quantifying execution of
treatment. Assessment of treatment integrity would permit analyses more specifically of constructs of interest such as whether
stress influences or is influenced by integrity or execution of
treatment by the therapist.
Finally, we did not examine long-term effects of treatment. Our
prior work has shown that treatment outcomes with PSST and
PMT are maintained up to a year or 2 later at the level achieved at
posttreatment. However, the long-term effects of PPS were not
studied here, and one must be commensurately cautious about the
impact. It might well be that the PPS exerts short-term impact and
we provided no evidence to suggest otherwise.
There are issues that are pertinent to this study but have broader
implications. First, the present study portrays stress as a villain.
The deleterious effects of stress on mental and physical health
outcomes are well established. Yet, it is likely that stress of the
type we studied or some levels of that stress do not invariably
disrupt child-rearing practices among parents of conduct problem
children. Indeed, there might even be beneficial effects. Alternatively, a moderator we have yet to study might negate deleterious
effects of stress. This study did not analyze stress in a way to
reveal these relations, and we are wary of implying uniform, linear,
and simplistic effects of parental stress or its amelioration.
Second, there is a strategic issue about treatment research that
this study raises. We began with an evidence-based treatment and
added a component to enhance treatment outcome. This is a useful
strategy because evidence-based treatments are not effective for
everyone and not sufficiently effective for many children. Efforts
to supplement and augment treatments are important, and there are
very few such efforts in the child treatment literature (Kazdin,
2000a). Consequently, adding a component to enhance treatment
impact seems reasonable and perhaps even wise. Yet there are
serious limitations of this approach.
One cannot keep adding components to a treatment that might
enhance or indeed actually does enhance therapeutic change. From
a methodological standpoint, demonstrating that any new component will make a difference can be quite difficult because of
limitations in assessment (e.g., ceiling effects) and research design
(e.g., sample sizes needed to show small increments in effects).
The methodological and design constraints limit how much one
can add to an evidence-based treatment and expect to show an
effect, even if there is one. From a more clinical and service
delivery standpoint, the strategy of adding components to treatment has further limitations. Patient attrition, already high in child,
adolescent, and adult therapy (40%– 60%) is a partial function of
the demands made of the client (Kazdin, Holland, & Crowley,
1997) and the duration of treatment (Phillips, 1985). Adding a
component to treatment that increases either one of these is quite
likely to cause greater attrition so that fewer patients will complete
treatment. Also, of course, there is the monetary cost. Improving
treatment by adding components may add to the number of sessions and raise reimbursement issues and questions about incremental costs in relation to incremental benefits.
Two other strategies than ours can be used to enhance treatment
effects. First, for evidence-based treatments, it is important to
identify who is not likely to respond to treatment or who has not
in fact responded during the course of treatment. These individuals
may warrant a targeted extra or “new and improved” treatment
(i.e., a stepped-care model; Haaga, 2000). Providing an added
component of treatment to everyone, as in the present study, may
not be optimal or necessary; many of the children and families may
respond well or well enough to the treatment in its less intensive,
less costly, and more abbreviated form. In the present study, PPS
was given to everyone assigned to that condition. The approach of
this study may not be the best for improving therapy, especially for
improving outcomes for those who need something new or different. That is, raising the mean level for the entire group (that
received the extra treatment) may not be as important as targeting
those who do not respond and raising just their mean.
Second, understanding the mechanisms through which treatment leads to change is another strategy for enhancing treatment
effects. It is still the case that we know very little about why
treatments lead to change, even among the evidence-based treatments (Kazdin, 2000a). This means that the treatments we are
using, without any added components, may not be optimal. It may
be premature to add further components to treatment without
understanding how to optimize change of the treatment to which
the components are added. Moreover, these components, even if
they enhance outcome, further raise the importance of understanding mechanisms (i.e., it will be essential to understand why any
new component improves outcome).
The present study focused on stress of the parent over the course
of treatment and the effects of this focus on several outcomes. As
predicted, addressing parent stress during treatment improved
treatment outcome for children and parents and reduced the burden
of treatment that parents experience while attending therapy. The
next steps are those we have outlined in our comments about
alternative strategies to improve treatment effects. Specifically, it
will be important to identify youths who respond well with the
core or minimal treatment, to provide additional or new interventions to only those who require them, and to understand for
responders and nonresponders the mechanisms through which
change occurs. Understanding the mechanisms of change will be
critical. Indeed, if the mechanisms of core treatments were better
understood, it might be possible to enhance treatment effects
markedly without new components such as the one evaluated in
this study.
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Received October 8, 2001
Revision received March 19, 2002
Accepted May 13, 2002 䡲
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