preadolescent conduct problems in girls and boys

Preadolescent Conduct Problems in Girls and Boys

JULIE MESSER, PH.D., ROBERT GOODMAN, M.D., RICHARD ROWE, PH.D., HOWARD MELTZER, PH.D.,

AND BARBARA MAUGHAN, PH.D.

ABSTRACT

Objective: To examine sex differences in correlates of disruptive behavior disorders (DBDs) in preadolescent children

using indicators of a wide range of well-established risk factors for DBDs and outcomes 3 years after initial assessment.

Method: Analyses were based on data for 5- to 10-year-olds (n = 5,913) from the British Child and Adolescent Mental

Health Survey 1999, and a 3-year follow-up of selected subsamples (n = 1,440) at ages 8 through 13 years. DSM-IV di-

agnoses were assigned using the Developmental and Well-Being Assessment at both contacts. Results: Boys and girls

were equally exposed to most social and family risks for DBDs, with little evidence of differential sensitivity to these risks.

Boys were exposed more to neurodevelopmental difficulties, attention-deficit/hyperactivity disorder, and peer problems

and had lower rates of prosocial behaviors; together, these factors and physical punishment could account for 54% of

the observed sex differences in DBDs. At follow-up, outcomes for girls and boys with DBDs were very similar. For children

with subthreshold conduct problems at initial assessment, boys were more likely to go on to exhibit DBDs than were girls

(25% versus 7%). Conclusions: Sex differences in the levels of a variety of child characteristics and interpersonal factors

are likely to be important in understanding sex differences in risk for DBDs in preadolescent samples. J. Am. Acad. Child

Adolesc. Psychiatry, 2006;45(2):184–191. Key Words: sex differences, preadolescent conduct problems, follow-up,

epidemiology.

Epidemiological studies have consistently shown thatboys are more likely to show disruptive behavior disor-ders (DBDs) than girls (Loeber et al., 2000). Sex ratiosare especially marked in the preadolescent years, whenrates of conduct disorder (CD) and oppositional defiantdisorder (ODD) are three to four times higher in boys.Partly as a result, relatively little is known about conductproblems in young girls (Hipwell et al., 2002), and thefactors that contribute to sex differences, likely to shed

light on risks of DBDs in both sexes (Rutter et al.,2003), continue to be poorly understood.

Of the many processes that may contribute to sex dif-ferences, two have received particular attention: first, thatboys may be more exposed to key risks for externalizingdisorders than girls, and second, that they are more vul-nerable to those risks (Storvoll and Wichstrom, 2002).Moffitt et al. (2001), focusing on adolescent samples,reported some of the most comprehensive tests of thesepropositions to date. Using longitudinal data from theDunedin Multidisciplinary Health and DevelopmentStudy, they explored sex differences in exposure to twobroad categories of risk, social/family adversities andchild-based characteristics, in predicting adolescent CD.They found little evidence of sex differences in exposureto family adversity, although levels of harsh parentingwere higher among boys. In addition, although familyand parenting factors were important risks for conductproblems within each sex, they did little to account fordifferences between the sexes in levels of antisocial be-havior. The picture was quite different in relation to in-dividually based risks (neurocognitive indicators, hyperactivity,

Accepted August 23, 2005.Drs. Messer, Maughan, and Rowe are with the MRC Social, Genetic and De-

velopmental Psychiatry Centre, Institute of Psychiatry, King’s College London;Dr. Goodman is with the Department of Child and Adolescent Psychiatry; In-stitute of Psychiatry, King’s College London; and Dr. Meltzer is with the Officefor National Statistics, London.This article was supported by Medical Research Council Programme Grant

G9901475 to Dr. Maughan. The original data collection was funded by theBritish Department of Health.Correspondence to Dr. Julie Messer, Box PO46, MRC SGDP Centre, Institute

of Psychiatry, 16 De Crespigny Park, London, UK SE5 8AF; e-mail: [email protected]/06/4502–0184�2006 by the American Academy of Child

and Adolescent Psychiatry.

DOI: 10.1097/01.chi.0000186403.13088.d8

184 J . AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 45:2, FEBRUARY 2006

and peer problems): boys were more likely to be exposedto these risk factors, and these variations in exposure werehighly salient for understanding sex differences in thelevels of conduct problems. Peer relationship factors ac-counted for 21% of the observed sex difference in CD,hyperactivity, and undercontrolled temperament for38%, and neurocognitive factors for 18%.Taken together,the full range of risks examined accounted for some twothirds of the difference between the sexes in antisocialinvolvement between ages 13 and 18 years.Evidence of contributors to sex differences in DBDs

in younger children is more scattered, although there arepointers that early parenting may affect boys and girlsdifferently (Crick and Zahn-Waxler, 2003). Other fac-tors highlighted in the preadolescent period includegirls’ more rapid biological, cognitive, and socioemo-tional development in early childhood, which may alsocontribute to variations in risk of disruptive behaviors(Keenan and Shaw, 1997). Girls are reported to be moreempathetic and prosocial than boys from the kindergar-ten years onward (Cote et al., 2002a), and their strengthsin these areas may function as protective factors againstthe development of externalizing problems (Crick andZahn-Waxler, 2003).In related debates, investigators have argued that core

features of antisocial behavior may differ in girls andboys (Crick and Zahn-Waxler, 2003). The DSM-IV(American Psychiatric Association, 1994) criterion setfor CD focuses heavily on behaviors more typically dis-played by boys, so that young girls with serious difficul-ties may be overlooked. Crick and Zahn-Waxler (2003)have drawn attention to girls’ greater use of relationalrather than physical aggression, and Zoccolillo et al.(1996) proposed lowering the symptom threshold forCD in girls to increase the sensitivity of the diagnosis.We used data from the British Child and Adolescent

MentalHealth Survey 1999 (B-CAMHS99), a population-based study, to explore a number of these issues. Weaddressed three questions: first, whether girls and boyswere differentially exposed to any of a range of well-established social, family, and individual risks of DBDs;second, whether they differed in sensitivity to these var-ious factors; and third, how far variations in exposure orsensitivity contributed to sex differences in rates of pre-adolescent DBDs.We used the follow-up data to explorethe extent to which girls and boys with DBDs at initialassessment were at risk of a disorder 3 years later and also(taking up the proposal of Zoccolillo et al. [1996])

whether current diagnostic criteria selectively excludegirls with subthreshold symptoms who are nonethelessat increased risk of adverse later outcomes.

METHOD

1999 Study

Participants. The survey was funded by the British Department ofHealth and carried out by the Office for National Statistics; full de-tails of the design and measures are available elsewhere (Ford et al.,2003; Meltzer et al., 2000). Briefly, the Child Benefit Register wasused as a sampling frame to identify children ages 5–15 in England,Scotland, and Wales; because Child Benefit is a universal state ben-efit, this register provides a relatively complete basis for sampling thechild population in the United Kingdom. A sampling frame wasdeveloped from the register of postal sectors (excluding families with-out a zip code); of the 9,000 postal sectors covering Great Britain,475 were sampled with a probability related to the size of the sector,and stratified by Regional Health Authority and within that by so-ciodemographic groupings. Response rates were high (83% of eli-gible families; for details, see Ford et al., 2003; Meltzer et al., 2000).For the 5- to 10-year-olds studied here, information was obtainedfrom parents and teachers on a total of 5,913 children (50.6% girls).Ethnic minorities accounted for 8.9% of the sample, a representativeproportion of the British population (see Ford et al., 2003, for details).Measures. DSM-IV psychiatric disorders were assessed using the

Development and Well-Being Assessment (DAWBA; http://www.dawba.com; Goodman et al., 2000). For 5- to 10-year-olds, theDAWBA consists of a parental interview and related teacher ques-tionnaire. Data on symptoms and psychosocial impairment areprobed through a structured, computer-assisted interview; verbatimdescriptions of symptomatic behaviors are also noted. PreliminaryDSM-IV diagnoses are generated by computer algorithm on thebasis of symptom and impairment data, using evidence from eachavailable informant. Clinicians then review the computerized dataand verbatim transcripts, accept or amend the computer-generateddiagnoses, and assign not otherwise specified (NOS) diagnoses. In B-CAMHS99, all ratings were completed by two clinicians supervisedby R.G. (see Ford et al., 2003 for details). Chance-corrected agree-ment between the two raters on 500 cases was 0.86 for any disorder(SE = 0.04) and 0.98 (SE = 0.02) for externalizing disorders.

Social, family, and individual characteristics were coded into bi-nary variables unless otherwise stated. Percentages show the propor-tion of all 5- to 10-year-olds exposed to each risk.

Social and economic disadvantage. Neighborhood socioeco-nomic characteristics were assessed using the ACORN classificationscheme (CACI Information Services, 1993), a U.K. geodemographicclassification system for zip code areas based on census informationand lifestyle data: children living in the most disadvantaged neighbor-hoods (25.7%) were contrasted with all other children. Low familyclass was endorsed if the highest occupational status of either parentwas partly skilled or unskilled (Standard Occupational Classification;Office of Population Census and Surveys, 1991) or if neither parenthad ever worked (22.9%). Low income was coded when householdincome was less than £200 ($370 U.S.) per week (25.0%).

Family structure and size. Two indicators were constructed tocontrast single-parent families (21.6%) and reconstituted families(9.9%) with all other family types. Large family size was codedfor families with four or more children (12.2%).

PREADOLESCENT CONDUCT PROBLEMS

J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 45:2, FEBRUARY 2006 185

Family stress and functioning. Family stress was indexed byexposure to three or more major life events (12.0%). Family func-tioning (5%) was assessed using the General Functioning Scale ofthe McMaster Family Assessment Device (Miller et al., 1985).

Parental characteristics. Low maternal education was coded formothers who left school without any formal qualifications or withqualifications below General Certificate of Secondary Education(22.7%). Teen motherhood (5.6%) reflected maternal age at the in-dex child’s birth. Parental criminality (5.5%) was coded if eitherparent had appeared in court during the index child’s lifetime. Pa-rents’ currentmoodwas assessed using the 12-item version of theGen-eral Health Questionnaire (Goldberg and Williams, 1988); 23.2% ofparents were identified as having low mood (a score of three or more).

Physical punishment. The measure of physical punishmentconsists of parents’ use of physical disciplinary techniques, includingfrequent smacking (i.e., equivalent to spanking) any use of a belt orstrap, and any shaking of the child (15.9%).

Child’s characteristics. Neurodevelopmental problems (epi-lepsy, cerebral palsy, muscle or coordination difficulties) were scoredfrom parental report (3.3%). Continuous measures of conductproblems, peer difficulties, and prosocial behavior were derivedfrom the parent-rated Strengths and Difficulties Questionnaire(Goodman, 2001). Reading was assessed using the British AbilityScales, Second Edition (Elliott et al., 1996); children classified asshowing low reading performance scored in the lowest 5% of theirage distributions. A small proportion of children (8%) declinedto complete the reading test. As a result analyses including readingperformance were necessarily calculated on somewhat reducednumbers.

3-Year Follow-up Study

Participants. Three years after the initial study, all children withdisorder, together with a one-in-three random sample of those with-out disorder, were selected for follow-up (Meltzer et al., 2003).Follow-up interviews were successfully completed for 90% ofselected nondisordered children and 81% of the disordered sample,for a total of 1,440 5- to 10-year-olds (49% girls). Data collectionprocedures were similar to those used in the initial study, and DSM-IV disorders were again assessed using the DAWBA.

To assess the effects of lowering diagnostic thresholds on detec-tion of poor later outcomes, we defined a group showing subthresh-old conduct problems at initial assessment, using parent and teacherscores from the conduct problems subscale of the Strength and Dif-ficulties Questionnaire. Excluding children with a Time 1 DBDdiagnosis, we assigned the next highest 5% Time 1 conduct scoreson either parent or teacher questionnaire to this subthreshold group(5.5% girls and 9.7% boys).

Statistical Analyses. The survey models of STATA (StataCorp,2003) were used for all of the analyses. These models allowed theuse of weights to account for the sample design and to correctfor nonresponse (see Meltzer et al., 2000 for details). For the fol-low-up analyses, additional weights were applied to ensure that dis-tributions continued to reflect characteristics of the full 1999 sample(Meltzer et al., 2003). All descriptive data are based on weightedpercentages. Logistic regression was used for analysis of binary out-comes and ordinal logistic regression for analysis of scale scores.

RESULTS

1999 Study

Prevalence and Comorbidity. Table 1 shows the prev-alence of DSM-IV CD, ODD, and DBD NOS in 5- to10-year-old girls and boys in B-CAMHS99. Rates ofDSM-IV CD and ODD were broadly in line with thosereported in previous studies. ODD was more commonthan CD in this preadolescent age group, and all of theCD/ODD categories were diagnosed at least twice asfrequently in boys as they were in girls. There wereno significant age variations in the prevalence of anyof the selected disorders in either boys or girls (fulldetails available from the primary author). To achievemaximum statistical power, we combined all cases witha CD/ODD diagnosis (ODD, CD, and DBD NOS)across age for all subsequent analyses; we refer to thiscombined grouping as having DBDs.

Risk Factors and Correlates. Sex differences in expo-sure to known risks for DBDs were assessed by compar-ing levels of each factor in girls and boys in the sample asa whole. Girls and boys were equally exposed to all thefamily and social risks with the exception of physicalpunishment, where parents of 18% of boys but only14%of girls reported using physical methods to disciplinetheir children (odds ratio [OR] = 1.4, 95% confidenceinterval [CI] = 1.2–1.6, p < .001). Exposure to individualrisk factors varied more systematically between the sexes,with boys more likely to have a diagnosis of ADHD

TABLE 1Prevalence of DSM-IV Disruptive Behavior Disorders in 5- to 10-Year-Old Girls and Boys

Girls (n = 2,992), % Boys (n = 2,921), % OR (95% CI) p

Any CD 2.4 6.0 2.5 (1.9–3.4) <.001ODD 1.7 3.8 2.3 (1.7–3.2) <.001CD 0.3 1.1 3.5 (1.6–7.7) .001

DBD NOS 0.5 1.1 2.4 (1.2–4.7) .01

Note:OR = odds ratio; CI = confidence interval; CD = conduct disorder; ODD = oppositionaldefiant disorder; DBD NOS = disruptive behavior disorders not otherwise specified.

MESSER ET AL.


(3.6% versus 0.8%, OR = 4.5, 95% CI = 2.9–7.2,p < .001), to have had neurodevelopmental problems(4.3% versus 2.4%, OR = 1.8, 95% CI = 1.4–2.4,p < .001), and to show poor reading performance(6.7% versus 3.3%, OR = 2.1, 95% CI = 1.6–2.7,p < .001) than girls. Parent reports of peer difficultiesand prosocial behaviors also varied, with girls rated sig-nificantly higher on the prosocial behavior scale (girlsmean = 8.9, SD = 1.4; boys mean = 8.4, SD = 1.7;b = –0.6, 95% CI = –0.7 to –0.5. p < .001) and loweron the peer problems scale (girls mean = 1.3, SD = 1.6;boys mean = 1.5, SD = 1.7; b = 0.1, 95% CI = 0.1–0.2p = .001) than boys. No other factors showed significantsex differences.With one exception (teen motherhood), all of these

factors were significantly associated with DBDs in bothgirls and boys, with odds ratios ranging from 1.5 to >5.

As Table 2 shows, these associations were generally sim-ilar for children of both sexes and gave little evidence ofdifferential sensitivity to particular risks. Formal testsfor interactions between child sex and each risk factorrevealed only twomarginally significant effects (for phys-ical punishment and peer problems). In each case, how-ever, the effect was contrary to the differential sensitivityhypothesis: exposure to both physical punishment andparent-rated peer problems were somewhat morestrongly associated with DBDs in girls than in boys.To test how far boys’ greater exposure to some risks

contributed to sex differences in DBDs, we undertooka series of logistic regression analyses, first includingchild sex as the sole covariate, then adding other corre-lates that differed in level between boys and girls. Table 3gives the results, showing the ORs and 95% CIs for sexafter the inclusion of each factor, and the percentage

TABLE 2Social, Family, and Individual Correlates of DBD in 5- to 10-Year-Old Girls and Boys

Girls Boys

No DBD

(n = 2,919)%

DBD

(n = 73)% OR

95%CI

No DBD

(n = 2746)%

DBD

(n = 175)% OR

95%CI

SexInteraction

Social and economic factors

Disadvantaged neighborhood 25.4 38.0 1.8* 1.1–3.0 24.9 39.8 2.0*** 1.5–2.7 NSLow social class 22.7 41.2 2.4*** 1.4–3.9 21.5 38.7 2.3*** 1.6–3.2 NSLow income 25.0 48.5 2.8*** 1.8–4.5 22.9 46.8 3.0*** 2.2–4.0 NS

Family structure and sizeSingle parent 21.5 44.1 2.9*** 1.7–4.7 20.0 40.6 2.7*** 2.0–3.8 NSReconstituted family 9.9 24.6 3.0*** 1.7–5.2 9.3 15.2 1.8** 1.1–2.7 NS

Large family 12.1 24.1 2.3** 1.3–4.1 11.4 21.5 2.1*** 1.5–3.1 NSFamily stress and functioning‡3 Adverse life events 11.3 26.4 2.8*** 1.7–4.6 11.2 28.5 3.1*** 2.2–4.5 NSPoor family functioning 4.1 17.1 4.9*** 2.7–9.1 4.5 20.1 5.3*** 3.6–7.8 NS

Parental characteristics and parentingLow maternal education 22.9 43.1 2.6*** 1.6–4.1 20.7 42.5 2.8*** 2.1–3.9 NSTeenage parent 5.4 8.6 1.7 0.7–4.0 5.5 11.0 2.1** 1.3–3.5 NS

Parent has had court appearance 5.2 16.3 3.5*** 1.9–6.7 4.8 16.0 3.7*** 2.5–5.7 NSParent’s current mood 22.7 44.1 2.7*** 1.7–4.3 21.4 50.5 3.7*** 2.7–5.1 NSUse of physical punishment 13.3 32.9 3.2*** 1.9–5.3 17.4 26.1 1.7** 1.2–2.4 .051

Child characteristicsADHD 0.5 13.4 30.9*** 13.5–70.8 2.0 28.3 19.2*** 12.3–30.1 NSInternalizing disorders 2.9 16.6 6.6*** 3.5–12.5 2.5 16.5 7.8*** 5.0–12.2 NSNeurodevelopmental problem 2.1 14.1 7.6*** 3.9–14.8 3.7 13.2 3.9*** 2.4–6.3 NS

Low reading performance 3.1 12.3 4.3*** 1.9–9.7 5.9 21.1 4.3*** 2.7–6.7 NSPeer problems (SDQ): mean 1.3 4.0 2.7*** 2.1–3.3 1.4 3.4 2.0*** 1.6–2.4 .043Prosocial behavior (SDQ): mean 8.9 7.2 –1.7*** –2.2 to –1.2 8.5 7.0 –1.5*** –1.8 to –1.1 NS

Note: Numbers vary slightly due to occasional missing data. NS = not significant; ADHD = attention-deficit/hyperactivity disorder;SDQ = Strengths and Difficulties Questionnaire.* p £ .05; ** p £ .01; *** p £ .001.



reduction in the initial effects for sex. Entered individ-ually the risk factors had differing levels of impact, withphysical punishment accounting for the smallest reduc-tion in the sex effect and prosocial behavior the largest.In a multivariate model, physical punishment, peer dif-ficulties, low reading performance, comorbid ADHD,and prosocial behavior were each independently associ-ated with DBDs. Adjusting for these factors, the OR forsex was significantly lower than in the single predictormodel (1.5 versus 2.4), with the model coefficientsreduced by >50% (single factor model: b = .891; five-factor model: b = .412; F = 7.95, df = 1,244, p = .005).

3-Year Follow-up Study.

Table 4 reports findings from the 3-year follow-up ofsubsets of the original study children. There was consid-erable stability in risk for DBDs across the follow-upperiod: children with a Time 1 diagnosis of DBD weremuch more likely to have a similar diagnosis 3 years laterthan were children with no Time 1 DBD diagnosis(boys: 46% versus 5%, girls: 40% versus 2%). Althoughexternalizing disorders were by far the most commonlater difficulties, Time 1 DBDs also put children at con-siderably increased risk of internalizing problems. As Ta-ble 4 shows, risks of both externalizing and internalizingdisorders were at least as marked for girls with a DBDdiagnosis at Time 1 as for boys, and tests for interactionswith child sex failed to identify any significant effects.Turning to outcomes for children with subthreshold

conduct problems at Time 1, the findings suggested that

TABLE 3Factors Associated With Reduction in Sex Differences in DBD

M:F OR(95% CI)

% Reductionin Coefficient

for Sex

Child sex only 2.44 (1.8–3.3)AddingPhysical punishment 2.36 (1.8–3.2) 3.5

Neurodevelopmental problems 2.33 (1.7–3.1) 5.0Low reading performance 2.25 (1.7–3.0) 8.8Peer problems 2.24 (1.7–3.0) 9.3

ADHD 2.00 (1.5–2.7) 22.9Prosocial behavior 1.88 (1.4–2.6) 29.1Joint model including 5

independentlysignificant risks 1.52 (1.1–2.1) 53.7

Note: All analyses based on cases with complete data on all mea-

sures (n ¼ 5,379). M = male; F = female.

TABLE

4Rates

ofDSM

-IV

Disordersat

Tim

e2forNoDisorder,Subthreshold,andDBD

Groupsat

Tim

e1

Girls

Boys

Tim

e1Group

OR(95%

CI)

Tim

e1Group

OR(95%

CI)

Tim

e2

Disorders

No

Disorder

(n=609)%

Subthreshold

(n=35)%

DBD

(n=44)%

DBD

vsNo

Disorder

Subthreshold

vsNo

Disorder

DBD

vs

Subthreshold

No

Disorder

(n=589)%

Subthreshold

(n=57)

%

DBD

(n=106)

%

DBD

vsNo

Disorder

Subthreshold

vsNo

Disorder

DBD

vs

Subthreshold

AnyDSM

disorder

5.5

19.3

48.3

16.2***

(8.4–31.1)

4.1**

(1.7–10.0)

3.9**

(1.4–10.8)

7.1

40.1

54.9

15.8***

(9.5–26.3)

8.7***

(4.6–16.5)

1.8

(0.9–3.4)

Externalizing

1.4

6.7

46.6

62.7***

(25.2–156.4)

5.2*

(1.3–20.1)

12.1***

(3.1–46.8)

4.1

34.7

50.8

23.9***

(13.6–42.0)

12.3***

(6.2–24.3)

1.9*

(1.0–3.7)

DBD

1.3

6.7

39.9

50.1***

(19.5–128.8)

5.4*

(1.4–21.5)

9.2***

(2.4–35.8)

2.7

25.4

46.0

31.1***

(16.5–58.8)

12.5***

(5.7–27.2)

2.5**

(1.3–5.0)

Internalizing

3.7

14.8

14.8

4.6***

(1.8–11.4)

4.5**

(1.7–12.3)

1.0

(0.3–3.4)

3.1

5.4

15.8

5.9***

(3.0–11.8)

1.8

(0.5–6.9)

3.3

(0.8–12.8)

Note:DBD

=disruptive

behaviordisorder;Subthreshold=highparentor

teacher

StrengthsandDifficultiesQuestion

naire

conductratings;Externalizingdisorders=conduct

disorder,oppositional

defiantdisorder,conduct

disorder

not

otherwisespecified,andattention

-deficit/hyperactivity

disorder;Internalizingdisorders=anydepressionandany

anxietydisorder;AnyDSM

disorder

=externalizing,

internalizing,

ticdisorders,eatingdisorders,andpervasive

developmentdisorders.

*p£.05;**

p£.01;***p£.001.

MESSER ET AL.


high parent or teacher ratings did identify a group ofchildren at increased risk of later difficulties, althoughoutcomes for these groups were somewhat different forgirls and boys. For girls, risks of any subsequent disor-der, of later externalizing disorders, and of later DBDsall were elevated by comparison with girls with no di-agnosis at Time 1, but much less so than for those withTime 1 disorder. Statistical comparisons showed thatrates of any externalizing disorders and DBDs in the sub-threshold group were significantly different from otherTime 1 groups. Risks of later internalizing disorders,by contrast, were much elevated by comparison with girlswith no DBD disorder at Time 1, but almost exactlyequivalent to those of girls in the Time 1 DBD group.For boys, the pattern differed in twomain ways. First,

boys with subthreshold Time 1 conduct problems werenot at significantly increased risk of later internalizingdiagnoses. Second, they were considerably more likelythan boys with no diagnosis at Time 1 to show an ex-ternalizing disorder at follow-up. Although tests againshowed that the subthreshold group differed from bothother groups on these contrasts, differences from boyswith Time 1 DBDs were modest, especially in terms ofrisk for later externalizing disorders. Formal tests of gen-der differences in prediction to later externalizing dis-orders identified a significant interaction, such thatboys in the subthreshold group were more likely togo on to show an externalizing diagnosis than were girls(OR = 0.2, 95% CI = 0.0–0.7, p = .019). No other in-teractions with sex were statistically significant.

DISCUSSION

Sex Differences in Correlates of DBDs

To explore correlates of sex differences in DBDs, wefollowed the three-step strategy suggested by Rutteret al. (2003), testing first for sex differences in exposureto known risks, next for sex differences in sensitivity torisk, and finally the extent to which variations in eitherof these processes could account for observed sex differ-ences in rates of DBDS.In terms of exposure, the findings differed consis-

tently between social and familial risks on the one handand individual child characteristics associated withvulnerability to DBDs on the other. Across the rangeof social and family factors assessed in B-CAMHS99only one, exposure to smacking and other forms of

physical punishment, was more common in boys thanin girls. For many child-based factors, however, boysconsistently had higher rates: they were more likelyto have experienced neurodevelopmental problems,they had higher rates of reading difficulties and prob-lems in peer relationships, and they also had higher lev-els of ADHD and lower levels of prosocial behaviors.All of these factors, from broad social indicators to child

and family characteristics, showed strong associations withrisk for DBDs in preadolescent children of both sexes. Theonly exception to this pattern was teen motherhood, inwhich results fell slightly below conventional significancelevels for girls. More important, the strength of these as-sociations was similar in boys and girls, suggesting thatchildren of both sexes are equally sensitive to this rangeof risks. Formal tests for interactions with child sex iden-tified only two significant effects: physical punishmentand peer problems, although more common in boys,were more strongly associated with DBDs in girls. Be-cause this part of our analyses was cross-sectional, wecannot be certain of the direction of these effects. In re-lation to peer problems, for example, the relative rarityof peer difficulties in girls may make them more impor-tant as risk factors for DBDs; alternatively, the relativerarity of conduct problems may make them especiallyalienating to peers. Unfortunately, the sample designfor the follow-up of B-CAMHS99 sample did not pro-vide adequate power to test these associations longitu-dinally; we must await findings from other longitudinalstudies to test these competing hypotheses.The third step in this stage of the analyses involved

testing how far risks that did differ in base rates betweenboys and girls may contribute to sex differences inDBDs.Here, our findings in 5- to 10-year-olds showed closeparallels with those of Moffitt et al. (2001) in adolescentsamples, while also suggesting some age-related varia-tions in risk. Like Moffitt et al. (2001), we found thatboys’ greater likelihood of neurocognitive deficits andhyperactivity/ADHD were strongly associated with sexdifferences in rates of DBDs, whereas contributionsfrom family-related risks weremuchmoremodest. Find-ings from the two studies differed in two main ways.First, peer-related risks accounted for a much larger pro-portion of variance in sex differences in adolescent CD(21%) than in our analyses of preadolescent children(6%). Our indicator of peer risk (centering on problemsin relationships with peers) was more limited than themeasure used by Moffitt et al. (2001), so that some of



these variations may reflect methodological factors. Inaddition, however, it seems likely that the differencesalso reflect developmental change, with peer-related fac-tors more salient risks for DBDs in adolescence than inthe childhood years.Second, we found that sex differences in prosocial be-

haviors contributed in important ways to sex differencesin DBDs in these preadolescent samples. Previous com-mentators have suggested that girls’ more rapid socioe-motional development in early childhood may contributeto variations in risk of DBDs (Keenan and Shaw, 1997)and that prosociality may be a key temperamental riskfor conduct problems (Lahey andWaldman, 2003). As-sociations between prosocial and antisocial tendenciesare likely to be complex; evidence already suggests, how-ever, that young girls are consistently rated as more‘‘helpful’’ in early childhood than young boys (Coteet al., 2002a), that childhood prosocial behaviors pro-tect against the development of externalizing problems(Hay and Pawlby, 2003), and that a lack of helpfulnessmay be an especially important risk for CD in girls(Cote et al., 2002b). Although the cross-sectional natureof this study does not allow us to explore this associationfurther, our findings add to an emerging body of evi-dence that sex differences in early prosocial behaviorsmay be important sources of variation in risk for anti-social behavior in boys and girls.The final section of our analyses focused on later out-

comes for children with DBDs. Like previous studies(Loeber et al., 2000), we found that continuity in exter-nalizing disorders was strong and that childhood DBDswere also associated with increased risk of later internal-izing disorders. In both of these areas, outcomes for chil-dren who met diagnostic criteria for DBDs were closelysimilar for boys and girls. We also used the follow-updata to explore the proposal of Zoccolillo et al. (1996)that current diagnostic criteria for CD may overlooka subthreshold group of girls at high risk of poor lateroutcomes. We used parent and teacher ratings of con-duct problems to identify a subthreshold group of thiskind. Outcomes for this subgroup highlighted clearlythe increased risk for children with subthreshold levelsof conduct problems, but differed from expectations intwo main ways. First, rather than suggesting that DSM-IV criteria are insensitive to externalizing problems ingirls (Zoccolillo et al., 1996), the data suggested thatsubthreshold boys were at much increased risk of laterantisocial difficulties. Second, although girls with

subthreshold conduct problems were more likely thannondisordered girls to show externalizing difficultiesat follow-up, their increased vulnerability was moremarked in the internalizing domain. Because the samplewas only ages 8 through 13 years at follow-up, this find-ing is unlikely to reflect the marked changes in sex ratiosfor internalizing disorders that emerge later in adoles-cence (Wade et al., 2002). Instead, two interpretationsseem possible. First, as other studies have suggested, het-erotypic continuities from externalizing to internalizingdisorders may be more characteristic of girls than boys(Costello et al., 2003), and early oppositionality may beespecially important to those links (Rowe et al., 2002).Second, early signs of internalizing disorders may bemisinterpreted as oppositionality in some anxious chil-dren, who become overwrought when stressed and re-spond by shouting and storming off. If this happensmore commonly with girls than boys, it could explainthe marked excess of later internalizing disorders in sub-threshold girls.

Limitations

Ford et al. (2003) discussed potential limitations ofthe B-CAMHS99 sampling frame and response rates inthe 1999 survey. We also used data from the 3-yearfollow-up, in which some further attrition arose; weused weights to account for nonresponse at both studycontacts and for features of the original sample design.Two other limitations are, however, important to note.First, B-CAMHS99 did not include measures of rela-tional aggression. In a series of important studies, Crickand Zahn-Waxler (2003) demonstrated the salience ofthis construct for antisocial behavior in girls; we hopeour findings stimulate further studies exploring risksfor sex differences where measures of relational aggres-sion are available. Second, our main analyses of risk fac-tors were cross-sectional, so we cannot be certain of thedirection of the effects involved. Many of the social andfamily factors that we examined reflect relatively long-standing risks, unlikely to be influenced by children’sdifficulties, but reciprocal effects are certainly plausiblein some instances. We must await longitudinal analysesin preadolescent samples to confirm the status of theassociations reported here.

Clinical Implications

Our findings in preadolescent samples show strongparallels with the longitudinal analyses of Moffitt

MESSER ET AL.


et al. (2001) of risks for adolescent CD. Both studiessuggest that social and family adversities are importantrisks for DBDs for both boys and girls, but that themarked sex differences in vulnerability to DBDs aremore likely to be associated with child-based risks. Inaddition, our findings add to a growing body of evi-dence showing that although rates of DBDs in pread-olescent girls are low (Hipwell et al., 2002), theirimplications are no less serious than in boys. Almost halfof these girls met diagnostic criteria for disorder 3 yearsafter initial assessment, and risks of later DBDs werelittle different from those of boys. Given the poorlong-term prognosis for early conduct problems in girls(Pajer, 1998), these findings underscore the key need foreffective interventions for young girls who display highlevels of disruptive behaviors. In addition, although cur-rent diagnostic criteria clearly identify children at great-est risk of poor later outcomes, our findings also suggestthat those with subthreshold difficulties are far from im-mune to later problems and may also be an importantfocus for clinical concern.

Disclosure: The authors have no financial relationships to disclose.

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