HOW EARLY CAN WE TELL?: PREDICTORS OF CHILDHOOD CONDUCT DISORDER AND ADOLESCENT DELINQUENCY

HOW EARLY CAN WE TELL?: PREDICTORS OF CHILDHOOD CONDUCT DISORDER AND ADOLESCENT DELINQUENCY*

JENNIFER L. WHITE TERRIE E. MOFFITT

University of Wisconsin, Madison

FELTON EARLS Harvard University

LEE ROBINS Washington University

PHIL A. SILVA University of Otago, New Zealand

It is often argued that intervention efforts can benefit from the early identi3cation of children at risk for antisocial disorders. Little is known, however about the predictive eflcacy of early predictors This study examined the predictive power of a variety of characteristics of the preschool child for antisocial outcome at ages I1 and 15. The subjects were 1,037 members of a longitudinal investigation of a New Zealand birth cohort. Groups with no disorders (n = 837), disorders other than antisocial disorders (n = 37), and antisocial disorders (n = SO) were defined. Preschool descriptors were screened for their predictive power. A discriminant function analysis was computed with the jive most promising preschool variables. The function correctly classijied 81% of subjects as antisocial, or not. at age 11, and 66% of subjects as delinquent, or not, at age 15. Having preschool behavior problems was the single best predictor

*This research was supported by USPHS Grant 7 R23MH-42723-01 from the Antisocial and Violent Behavior Branch of the National Institute of Mental Health and by the Graduate School of the Univesity of Wisconsin. The Dunedin Multidisciplinary Health and Development Research Unit is supported by the Medical Research Council of New Zealand. This research was also supported, in part, by the McArthur Foundation/ National Institute of Justice Program on Human Development and Criminal Behavior. The authors would especially like to express their appreciation and gratitude to Paul Stevenson, Dunedin Police Department, for his help with the arrest records. Thanks are also due to Jessie Anderson, who diagnosed the children at age 1 1, and to Douglas Needles, for his suggestions on earlier drafts of this paper. Finally, the authors also acknowledge the helpful comments of two anonymous reviewers.

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of antisocial disorders at age 11. This result is consistent with earlierfind- ings that, among measures assessed in childhood, behavior problems are the best predictor of later antisocial outcome.

INTRODUCTION

Considerable evidence exists to support the view that recidivistic criminal behavior in adults is often preceded by a history of antisocial behavior during childhood and adolescence (Kazdin, 1987; Robins, 1978). Much serious antisocial behavior in adulthood appears to be associated with a long-standing pattern of behavioral, interpersonal, and academic difficulties. This has been documented in a variety of investigations of the factors that place youths at risk for the development of later criminal behavior (for reviews of this litera- ture, see Kazdin, 1987; Loeber and Dishion, 1983; Offord, 1989).

Some studies have shown that antisocial behavior is remarkably consistent over time (Moffitt, 1990; Olweus, 1979). These studies suggest that intervention efforts may be more effective when waged as early as possible. In their review of the factors that predispose individuals to future antisocial behavior, Loeber and Dishion (1983:69) state that it is important “to establish the earli- est age at which such conduct problems become predictive, so that preventive efforts can take place while the conduct problems are not yet firmly stabilized.”

In the majority of studies, predictors of late adolescent delinquency and adult criminal behavior have been measured in school-aged children and adolescents, when conduct problems already appear to be stable (Gersten et al., 1976 Kirkegaard-Ssorensen and Mednick, 1977; Marsh, 1969; Reckless and Dinitz, 1972); Robins, 1978; Stott and Wilson, 1968; West and Farrington, 1973). Mitchell and Rosa (1981) employed a sample consisting of a whole school population, ranging in age from 5 to 15 years old. They found that reports by parents and teachers of behavioral problems were related to criminal outcome in adulthood. Correlations between behavioral problems at age five and adult criminality were not specified, however.

Only one study (Richman et al., 1982) was identified in which predictors of later antisocial behavior were systematically examined as early as the preschool age (but also, see Block et al., 1988, on early childhood personality precursors of drug use, in particular). Richman et al. (1982) reported a significant association between restlessness assessed at ages three and five and antisocial behavior at age eight, in a study employing behavioral, cognitive, and health variables.

This paper aims to fill the gap in knowledge that currently exists concerning the efficacy of preschool behavioral predictors of later antisocial behavior. It reports the results of a systematic, longitudinal investigation of a complete

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birth cohort. The primary goal of the study was to ascertain whether serious antisocial conduct disorders at age 11 could be effectively predicted as early as the preschool years. A second objective was to determine whether those variables that were the best preschool predictors of conduct problems at age 11 were also strong predictors of delinquency in adolescence (at age 15). Middle adolescence is the peak period for prevalence of delinquent behavior, and many adolescents emerge as delinquent who have no history of earlier antisocial behavior. Mixed among these “age-/normative” delinquents are adolescents whose delinquent behavior seems to be a continuation of early- onset behavioral problems in childhood (Moffitt, 1990). It is unclear, then, whether variables that might predict conduct problems in childhood would retain any predictive utility later on in adolescence. To address this issue, we examined the 10-year predictive ability of the set of characteristics measured at ages 3 and 5 that best predicted antisocial behavior at age 11.

The variables discussed in this paper are limited to characteristics of the child. Maternal and other family factors are being examined by Henry et al. (in preparation). A number of investigators have found that characteristics of the child are the most powerful predictors of the subsequent development of antisocial behavior. Predictive characteristics have been found to include behavioral (Loeber and Dishion, 1983; Robins, 1978), cognitive (Moffitt, 1990), and health variables (Mednick and Volavka, 1980). This study was based on data archived from the early assessment waves of an ongoing longitudinal study. Consequently, variables selected for examination were those for which archival data were available.

Our study combines a variety of methodological advantages. First, it employed a prospective, longitudinal design to study a complete birth cohort, thereby avoiding many sources of bias. Second, unlike many previous studies, we studied both boys and girls. Because only male subjects were used in most of the previous studies of the predictors of antisocial behavior, the generalizability of the results to females has been questionable. Third, a large spectrum of behavioral, cognitive, and health variables were available for analysis. Fourth, it was possible to conduct predictions with preschool variables across a wider age span within childhood and adolescence than had been previously examined (the prediction interval spans from 3 years of age to 15). Fifth, previous studies have investigated factors that distinguish between antisocial individuals and normal controls. However, they failed to determine whether the predictors were specific to conduct disorder only, or indicated a general risk for poor behavior or emotional dysfunction. In this study, predictors of conduct problems were distinguished from predictors of other psychiatric disorders (i.e., anxiety disorders, depression, and attention deficit disorder without hyperactivity). Finally, antisocial outcome is defined by reports from multiple sources (parent, teacher, self-report, psychiatric interview, police data) taken at multiple time points thereby ensuring that the

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positive cases had pervasive and persistent problems. Loeber and Dishion (1983) suggest that the use of multiple raters can ensure the stability of behavior across situations.

The goals of this study were to (1) identify preschool predictors of pervasive and stable antisocial behavior at age 11, (2) assess which preschool variables are the best predictors of this kind of antisocial behavior, (3) determine whether those predictors are specific to antisocial behavior, rather than being risk factors for maladjustment, in general, and (4) test whether the utility of the identified preschool predictors extends to delinquency in adolescence.

METHOD

SUBJECTS

The subjects were children in the Dunedin Multidisciplinary Health and Development Study, which has been described fully by Silva (1990). Briefly, the study longitudinally investigates the health, development, and behavior of a cohort of children born between April 1, 1972, and March 3 1, 1973 in Dun- edin, New Zealand. Perinatal data were initially obtained, and when the children were traced at three years of age, 1,139 children were eligible for inclusion by virtue of residence within the province. Of these, 1,037 (91%) were assessed at age three and form the base sample for longitudinal follow- up. Extensive psychological, social, and physical data were systematically collected for the cohort at ages 3, 5 , 7, 9, 11, 13, and 15. An investigation of the effects of sample attrition revealed no significant differences on behavioral measures assessed at ages 7 and 9 for the 924 members of the sample seen at age 11 and the 113 subjects who were not interviewed (Silva, 1990). When compared with New Zealand's general population, the cohort is slightly higher on socioeconomic status levels. On a six-level social class scale (Elley and Irving, 1972), 7% of New Zealand males, but 11.7% of cohort fathers, were rated at the professional level. Like the population of Dunedin as a whole, the cohort is primarily of European descent. Approximately 2% of the sample are from Maori and Polynesian backgrounds. The predominantly European background of the sample suggests that it is comparable to those from other English-speaking Western cultures.

MEASURES

A large number of preschool measures (33) were examined (see description in appendix). They covered aspects of physical health, cognitive and motor abilities, behavioral problems, and language development. Only the behavioral measures that were used to define the subject groups for study are described in detail here.

PREDICTORS OF ADOLESCENT DELINQUENCY 5 1 1

DIAGNOSTIC INTERVIEW SCHEDULE FOR CHILDREN-CHILD VERSION.

The Diagnostic Interview Schedule for Children-Child Version (DISC-C) is a structured diagnostic interview based on criteria in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-111; American Psychiatric Association, 1980) for the various disorders of childhood and adolescence (Costello et al., 1982, 1984; for reports of DISC-C reliability using the New Zealand cohort, see Anderson et al., 1987). All items refer to the child’s functioning over the previous year and are structured so as to elicit responses of no (0), sometimes (l), or yes (2). Diagnostic interviews were conducted with subjects to determine whether they met the DSM-I11 criteria for conduct disorder, attention deficit disorder, attention deficit disorder with hyperactivity, anxiety, and affective disorders at age 1 1 .

RUTTER CHILD SCALES A AND B

The Rutter Child Scales A and B (RCSA&B; Rutter et al., 1970) are 31- item and 26-item questionnaires designed to be filled out by parents and teachers, respectively. The items inquire about the major areas of a child’s behavioral and emotional functioning. The parent or teacher rates each item as does not apply (0), applies somewhat (l) , or certainly applies (2). The RCSA&B were supplemented with 16 items concerning inattention, impulsivity, and hyperactivity (see McGee et al., 1985). These additional items were derived from the DSM-I11 diagnostic criteria for attention deficit disorder and were rated in the same way as were the RCSA&B items. All items refer to the child’s behavior during the previous year.

REVISED BEHAVIOR PROBLEM CHECKLIST

The Revised Behavior Problem Checklist (Q&P-RBPC; Quay and Peter- son, 1983) is a parent and teacher rating instrument for the major categories of childhood and adolescent psychopathology. Only the parents completed the QBP-RBPC in this study. The Q&P-RBPC comprises 89 items, 77 of which load on four major and two minor subscales. Each item is rated does not apply (0), applies somewhat (l), or certainly applies (2). The major subscales of the Q&P-RBPC are conduct disorder, socialized aggression, anxiety-withdrawal, and attention problems-immaturity. They contain 11 to 22 items each and have yielded coefficient alpha reliabilities ranging from .82 to .94 (Quay, 1983).

SELF-REPORT EARLY DELINQUENCY

The Self-Report Early Delinquency inventory (SRED; Moffitt and Siiva, 1988) is a 58-item instrument developed for use in New Zealand. It taps 29 illegal and 29 “norm-violating” behaviors. The 29 illegal items of the SRED were administered at age 15. The instrument contains both interview and

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card-sort questions that inquire about a variety of antisocial behaviors, including theft, assault, vandalism, and substance abuse. The items are scored dichotomously and each item is weighted for seriousness. Subjects are asked to report the Occurrence of delinquent behaviors for the previous year only. Moffitt and Silva (1988) have reported on the psychometric characteristics of this scale. The SRED yields an internal consistency coefficient (Kuder-Richardson Formula 20) of .90 and a test-retest stability coefficient of .85.

DESIGNATION OF ANTISOCIAL DISORDERS CASES

Three criteria were required for an individual antisocial disordered subject: (1) the presence of the criterion symptoms of antisocial disorders (AD) at age 11; (2) stability of this disorder across middle childhood; and (3) pervasiveness of this disorder across multiple raters. Whether subjects met these criteria was determined in the following manner:

First subjects who met the DSM-I11 diagnostic criteria for disorders of “externalized” behavior (see Quay and Werry, 1986, regarding the externaliz- indinternalizing disorder distinction in childhood) at age 1 1 were selected for the initial pool: either conduct disorder (CD), oppositional disorder (OPP), or attention deficit disorder with hyperactivity (ADD-H). The OPP and ADD-H cases were included because mean age-1 1 ratings on the antisocial subscales of the parent and teacher Rutter Child Scales were not significantly different for the three externalizing disorder diagnostic groups, which suggests that the differential diagnosis might have been more apparent than real with regard to antisocial symptom behaviors. The procedures followed for diagnosis of DSM-I11 behavioral disorders in the sample have been described by Anderson et al. (1987). Briefly, the criterion symptoms were obtained using the full DISC-C, which was administered to each 1 l-year-old subject by a child psychiatrist. Parent and teacher reports of undercontrolled behavioral symptoms had been collected using the RCSA&B, and Anderson et al. (1987) used them to corroborate and supplement each child’s interview data. The age-1 1 diagnostic criteria yielded 20 CD, 27 OPP, and 36 ADD-H diagnoses, a total pool of 69 possible cases (with diagnostic overlap).

Second, these possible cases were then assessed for pervasiveness and stability of antisocial behavior. To be judged stable the cases had to be rated beyond the 85th percentile on antisocial behavior subscales at a minimum of two out of three ages: 9, 11, and 13. The subscale ratings used were made by teachers, parents, and the child (see Table 1). Teachers completed the RCSB for the children at ages 9, 11, and 13. Parents completed the RCSA at ages 9 and 1 1, but used the Q&P-RBPC socialized aggression subscale at age 13. At age 11, subjects reported their conduct disorder symptoms on the DISC-C. At age 13, subjects completed the Self-Report Early Delinquency interview schedule, which includes 27 items listed as conduct disorder criteria in the

PREDICTORS OF ADOLESCENT DELINQUENCY 5 13

DSM-111. The cutoff at the 85th percentile was selected to be consistent with previous reports on psychopathology in this sample, and it tends to yield prevalence rates similar to those of epidemiological studies (e.g., Frost, 1989). Eighty percent of cases meeting the “two-age”criterion also met the criterion at all three ages.

Finally, to be judged pervasively antisocial, subjects had to be rated beyond the 85th percentile on antisocial behavior scales completed by at least two of five possible raters: the child, the parent, or any of three teachers who completed the RCSB at ages 9, 11, and 13 (see Table 1). In actuality, there were no cases with high ratings by two teachers that did not also have high ratings by parents. Sixty-six percent of cases meeting the two-rater criterion also met the criterion for three or more raters.

Table 1. Reports of Antisocial Behavioral Symptoms Used to Define the Antisocial Disorders Study Group

Reporter

Age Parent Teachers Child

9 RCSA” RCSBb

13 QP-RBPCd RCSB SRED‘ 11 RCSA RCSB DISC-C‘

NOTE: Subjects in the antisocial disorder group had (1) a diagnosis of undercontrolled disorder at age 11, (2) reports of antisocial behavior at two or more ages, and (3) reports from two or more persons.

Above 85th percentile on antisocial subscale of Rutter Child Scale A (RSCA). Above 85th percentile on antisocial subscale of Rutter Child Scale B (RSCB). Above 85th percentile on DISC-C symptom checklist for conduct disorder. Above 85th percentile on Quay and Peterson Revised Behavior Problem Checklist (QP-RBPC) socialized aggression subscale. Above 85th percentile on Self-Report Early Delinquency (SRED) Scale.

RESULTS

The results of the selection procedure are displayed in Table 2. Using the three criteria outlined above, 50 children were found to have stable and pervasive antisocial disorders. The cohort prevalence rate for stable, pervasive middle childhood antisocial disorders was 5.4%. These AD subjects were compared with 837 nondisordered subjects (ND), and with 37 subjects who had other diagnoses (OD) at age 11 (e.g., ADD with no conduct disorder symptoms, anxiety disorders, phobias, depression, and dysthymia). The 19 subjects who had some undercontrolled symptoms at 11, but who failed to meet criteria for stable and pervasive AD entered the nondisordered group,

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where they constituted less than 2% of that comparison group. (None of those 19 met criteria for other disorders.)

Table 2. Gender and Mean Antisocial Scale Ratings at Ages 9, 11, and 13 for No Disorder, Other Disorders, and Antisocial Disorders Comparison Groups

Variable

Group

ND OD AD

Gender* Boys Girls

Antisocial Ratings** Teacher at 9 Teacher at 1 1 Teacher at 13 Parent at 9 Parent at 11 Parent at 13

413 (49%) 25 (68%) 39 (78%) 424 (5 1 %) 12 (32%) 1 1 (22%)

1.55 (2.9) 1.81 (3.8) 7.27 (5.8) 1.03 (2.2) 1.51 (3.3) 6.22 (4.6) .79 (1.9) 2.25 (2.8) 4.48 (4.6)

3.52 (3.0) 5.25 (3.4) 8.70 (4.1) 1.98 (2.2) 2.47 (2.7) 6.18 (3.3) .87 (1.7) 2.30 (2.6) 3.93 (4.5)

~~

Chi-square (d.f. = 2) = 32.66, X2 <.001. ** All F's significant, p <.001.

Table 3 lists the 33 variables collected at ages three or five that were tested for predictive utility, by category and measurement age. Group comparisons on continuously distributed variables were tested using analysis of variance (ANOVA). Categorical variables were tested using chi-square. Because of the very large number of analyses conducted in this exploratory study, concern about false positive hypothesis testing is in order. All ANOVA F and x2 values were required to exceedp < .001.* Using this criterion, 1 1 continuous and 2 categorical variables showed significant group differences. The group means for the continuous variables, and the percentages for each group for the categorical variables, are shown in Table 4.

* Using a conservative level of significance resulted in the exclusion of several variables for which there were mean differences greater than . 3 standard deviations between the OD and AD groups. W e considered that differences greater than .3 S.D. may be clinically significant, even if they are not statistically significant. However, when these variables were included in the analyses, 74 subjects were excluded because data were lacking for some variables. Due to the interpretation problems associated with the reduction of subject numbers in both AD and NAD groups, those analyses are not reported here. However, the results were statistically significant, and all were in the same direction as those reported here.


Table 3. Child Characteristics Examined at Ages Three and Five

Health Age 3

Age Spoke Words Fine Motor Skill' Bayley Motor Skill Age Walked Independently Age Talked in Sentences Neurological Signs

McCarthy Motor Scales' Sleep Problemsbb Use of Health and Social Services for Childb Handednessb Enuresisb

Age 5

Cognitive Age 3

Peabody Picture Vocabulary Test' Reynell Receptive Language Development? Reynell Expressive Language Development"

Stanford-Binet I Q Draw-A-Man Test' Reynell Expressive Language Development Reynell Receptive Language Development Expected to be Above Average When Begins Schoolb

Age 5

Behavioral Age 3

Externalizing Behaviors (Hyperactivity, Aggression)' DilEcult to Managebb Vineland Social Maturity Scale Childhood Activities Childhood Experiences Internalizing Behaviors (Shyness)

Teacher's Rutter Behavior Problem Checklista Parent's Rutter Fkhavior Problem Checklist' No. Bad Behaviors Yesterday' Delays Obeying Parentsb Short Attention Spanb Mother Worries about BehavioP Rejectinflemanding versus Shy Personalityb 3 + Tantrums in the Past 6 Monthsb

Age 5

' Means among the no disorder, other disorders, and antisocial disorders groups differed significantly at age 11, p <.001. Categorical variable.

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Table 4. Significant Differences on Preschool Measures among the No Disorder, Other Disorders, and Antisocial Disorders Groups

Group

Standardized Measure" At 3 Years Old

Fine Motor Reynell Receptive Peabody Picture Vocabulary Test Externalizing Behaviors

At 5 Years Old Draw-A-Man Teacher's Rutter Parent's Rutter Binet IQ No. Bad Behaviors Yesterday McCarthy Motor Scales

Categorical Measureb At 3 Years Old

At 5 Years Old Difficult to Manage

Sleep Problems

N D O D A D ---

.04 -,05 - .55*

.05 -.42 -.48

.05 - .35 -.52 -.04 - .15 .75*

.06 -.20 -.78* -.05 .28 .60 -.08 .32 1.09*

.06 -.42 -.69 -.05 .24 .69

.05 .03 --.75*

8.6 8.6 29.8*

9.3 21.6 22.0

NOTE: ND = no disorder; OD = other disorders; AD = antisocial disorders. PPVT = Peabody Picture Vocabulary

All group means are Z scores. Mean Z scores differ significantly among the groups at p < .001. All group scores are percentages. Percentage scores differ significantly among the groups at p <.001. The antisocial disorder group mean is significantly different from both the no disorder and the other disorders groups at p < .05.

GENDER DIFFERENCES

Because boys and girls were not distributed proportionately across the three groups, gender differences were viewed as possible sources of confound for interpretation of group differences. (Gender information is included in Table 2.) Gender differences were also considered to be of possible substan- tive interest. All continuously distributed variables were entered into 2 x 2 ANOVAs, with diagnostic group and gender as the independent variables, so that interaction effects between gender and diagnosis could be tested. No significant interactions were obtained (allp values > .09), which suggests that relations between variables and diagnosis were not a function of gender. This


finding is in accordance with observations made in a review by Loeber and Stouthamer-Loeber (1987) - that predictors of girls’ delinquency are typi- cally consistent with predictors of boys’ delinquency. In addition, all categorical variables were cross-tabulated by diagnostic group separately for boys and girls, and the patterns of tabulation were examined for gender differences. No notable systematic differences were found between boys and girls in the patterns of their relations on the categorical variables with one exception: 38% of AD girls (n = 3) versus only 4% of AD boys (n = 1) were left- handed. This was the only detectable gender difference; because it involved so few subjects, further analyses were not conducted. Because the number of girls with AD was so small (n = 1 l), separate analyses for girls were likely to be unreplicable. Therefore, the remaining data presented in this paper have been collapsed across gender.

GROUP COMPARISONS

To identify variables that were specifically associated with the AD group, Tukey post hoc tests for means (Keppel, 1982) were conducted with variables for which significant group differences were found. Table 4 displays these results. Group mean standardized (2) scores are shown. Two variables at age three (difficult to manage and externalizing behaviors) and three variables at age five (McCarthy Motor Scales, Draw-A-Man, and the parent’s Rutter checklist) strongly differentiated AD subjects from both the OD and ND groups. Although parent-reported behavior problems at age five significantly differentiated between the AD and OD groups, the variable also significantly differentiated between the OD and ND groups.

Of the remaining variables, three (sleep problems, IQ, and receptive language at age three) differentiate the AD and the OD groups which suggests that these variables indicate a more general risk for poor adjustment. In addition, five variables (fine motor skill, expressive language at age three, vocabulary, teacher-reported behavior problems, and number of parent-reported “bad behaviors”) were found to differentiate between AD and ND cases only. The OD cases fell in between the AD and ND means on these variables and could not be distinguished from either.

DISCRIMINANT FUNCTION ANALYSIS

A direct discriminant function analysis was performed using the five continuous preschool variables that were found to differentiate the AD from both the OD and ND groups. The discriminant function calculated from those five measures was used to predict membership in two groups: AD subjects and non-antisocial subjects (NAD = OD + ND). One significant discriminant function was calculated, with a x2 (5) = 102.83, p <.001.

Based on the results of the discriminant function analysis, a classification

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table was constructed that compared true group membership with group membership predicted from the discriminant function. The groups com- prised AD subjects and NAD subjects. Of the entire sample of subjects, 81% were classified correctly. Approximately 70% of the AD cases and 81% of the NAD cases at age 11 were classified correctly with the discriminant function obtained from the five preschool predictors. The relative increase over chance (Loeber and Dishion, 1983) statistic was computed to be .62.

Next, analyses were conducted to determine the relative importance of the individual predictor variables to the discriminant function. These results are displayed in Table 5 . To avoid problems associated with multicollinearity

Table 5 . Squared Semipartial Correlations between the Preschool Discriminant Function and the Individual Preschool Predictors

Predictor Squared Semipartial

Rutter Behavior Problems, Age 5 Difficult to Manage, Age 3

.22

.12 Externalizing Behaviors, Age 3 .07 McCarthy Motor Scales, Age 5 .06 Draw-AMan, Age 5 .03

(intercorrelations among the five preschool variables ranged from .17 to .56), a direct multiple regression was performed, with the obtained discriminant function score as the dependent variable. The independent variables were the five preschool predictors. After adjustment for all other variables, “parent- reported behavior problems at age 5” (d = .22) was found to explain the most unique variance in the discriminant function scores. After parent- reported behavior problems, “difficult to manage” and “externalizing behavior problems” at age three, were the strongest contributors.

Analyses also were conducted to compare the predictive and classificatory ability of the individual preschool predictors. These analyses were aimed at assessing which variables were the best single predictors of disorder status at age 11. These results are reported in Table 6. Significant discriminant func- tions were computed for each of the five preschool variables. When the classificatory abilities of the individual preschool variables were compared, parent-reported behavior problems at age five was the individual variable that correctly classified the highest percentages of both the NAD and AD subjects. On its own, it successfully classified 80% of the NAD and 64% of the AD group. “Externalizing behavior” and “difficult to manage” at age three were the two variables that classified the largest number of subjects, 82.9% and 88.4% of the total subject pool, respectively. This reflects the fact that


Table 6. Discriminant Function and Classification Analyses: Individual Preschool Predictors

Xz (D.F.) Discriminant

Variable Function % N A D % A D Total Draw-A-Man Test 32.5*( 1) 69.2 70.0 69.3 Externalizing Behavior 30.4*( 1) 85.4 40.0 82.9 Difficult to Manage 19.4*( 1) 91.9 28.0 88.4 McCarthy Motor Scale 29.8*( 1) 76.5 66.0 76.0 Parent’s Rutter 63.3*( 1) 79.7 64.0 78.9

NOTE: NAD = non-antisocial disorders; AD = antisocial disorders. Cases with missing values were not used during the discriminant function analysis. During classification, means were substituted for missing values and cases containing missing values were classified.

p <.001.

both variables demonstrated particularly strong classificatory utility among the larger NAD group. Both variables correctly classified an extremely large percentage of the NAD group (85.4% and 91.970, respectively), which resulted in a high percentage of total correctly classified cases, but only a relatively small percentage of the AD group (40% and 28%, respectively). Often, results from discriminant function analysis are unstable. Our sample was large enough to allow a replication on separate randomly selected halves of the sample. The discriminant function for the five preschool variables yielded remarkably similar classification results in separate tests, which suggests the findings reported here are robust.

Taken together, the results presented in this section suggest that behavioral problems are the best preschool predictors of antisocial behavior at age 11, and that behavioral problems as early as age 5 , especially when rated by parents, can be predictive of future conduct problems.

PREDICTING ADOLESCENT DELINQUENT OUTCOME

Further analyses were conducted to assess whether the predictive efficacy of the preschool variables could be extended to delinquent behavior at age 15. These results are displayed in Table 7. The variety of self-reported delinquency at age 15 was found to differ significantly among the groups defined at age 11 (ND, OD, and AD), p <.001. Tukey tests were used to determine between-group differences. Both the OD and AD groups reported having engaged in significantly more different illegal delinquent acts than the ND group. Both the AD and the OD groups were also more likely than the ND group to have had at least one contact with the police; 32% of AD, 19% of

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Table 7. Delinquent Behavior at Age 15 for the No Disorder, Other Disorders, and Antisocial Disorders Groups

Group ND OD AD

Self-reported Delinquent Behavior at 15*

Mean (S.D.) 2.35 (4.2) 4.28 (6.9) 5.28 (7.4)

Police Contacts by Age 15**

% with 1 or more 10.2 18.9 32.0 9’0 with 2 or more 3.6 2.7 14.0

NOTE: ND N = 837; OD N = 37; AD N = 50. *F significant, p < ,001. **Chi-square (d.f. = 2) p <.001.

OD, and 10% of ND subjects had experienced at least one police contact by the age of 15. However, recidivists (those subjects who had two or more contacts with the police) were more than 3.5 times likely to be among the AD versus the ND or the OD groups; 14% of AD, 3% of OD, and 4% of ND subjects had already become recidivists by the age of 15.

The sample had a total of 130 incidents of police contact by age 15. The most common reasons for police contact were shoplifting, other theft, and burglary, which accounted for 62% of the offenses. Only 3.1% of the contacts were for assault. The ND, OD, and AD groups were responsible for 77%, 8% and 12% of the contacts, respectively, but accounted for 91%, 4%, and 5% of the sample, respectively. Thus, compared with their prevalence in the population, OD and AD subjects were overrepresented among police contacts, and ND subjects were underrepresented. These results suggest that children with either non-antisocial disorders or no disorders in middle childhood may become involved in relatively mild delinquent behavior by age 15. By contrast, children who exhibit stable and pervasive antisocial behavior at age 11 appear to be at greatest risk for recidivistic juvenile delinquency by age 15.

To assess whether the predictive power of the preschool predictors could be extended to delinquency at age 15, an additional discriminant function analysis was performed. Delinquent and nondelinquent groups at age 15 were defined for the purposes of the discriminant function analysis. Delinquents at age 15 were defined as those subjects who scored above the 75th percentile on self-reported delinquency and who had had at least one police contact by age


15. Using these criteria, 38 subjects were designated 3s delinquent. The remaining 886 subjects were assigned to the nondelinquent group.

A significant discriminant function analysis was computed using the five preschool variables as predictors of delinquency at age 15 (x’ = 11.49, d.J = 5 , p < .04). Using the five preschool predictors, delinquency status in adolescence was correctly classified for 65% of the subjects. Fifty-five percent of the delinquents and 67% of the nondelinquents were correctly classified. These results suggest that the predictive utility of the five preschool predictors extends only modestly to the adolescent period. In addition to the demonstration of conduct disturbance in middle childhood, there may be other factors that place youths at risk for delinquency at age 15 (e.g., proxi- mal social circumstances or childhood history of internalizing disorders).

DISCUSSION

This study had several important methodological advantages. The prospective design of the study enabled us to engage in prediction, not “postdic- tion,” which is biased by recall failure and/or selection of subjects based on their clinical symptomatology. The inclusion of girls enabled us to examine the possibility of differential predictability for girls versus boys. The results indicated that even when girls are studied, there are no notable gender differences in what predicts antisocial behavior. In contrast, Richman et al. (1982) found some evidence for gender differences in their sample. They reported that although restlessness at age three was equally predictive of antisocial outcome at age eight in both boys and girls, cognitive deficits were predictive for antisocial outcome in boys only. They found a nonsignificant trend for girls who developed antisocial disorders at age eight (as well as neurotic disorders) to score higher on cognitive tests at age three than girls without antisocial outcomes. Studies with larger numbers of female conduct-disordered subjects are needed to address the issue of gender differences.

A wide variety of variables was examined in our study. We found that, consistent with earlier reports (Loeber and Dishion, 1983; Monahan, 1981; Robins, 1966, 1978), early antisocial behavior is the best predictor of later antisocial behavior. It appears that this rule holds even when the antisocial behavior is measured as early as the preschool period. For at least some children, antisocial behavior appears to manifest itself early and remains stable. Onset as early as age three suggests the hypothesis that some antisocial behavioral characteristics may be components of temperament (Earls and Jung, 1987).

A high false positive rate, however, precludes the use of early antisocial behavior alone as a predictor of later stable and pervasive antisocial behavior. Of the 209 children predicted to have antisocial outcomes at age 11, 84.7% did not develop stable and pervasive antisocial behavior of the severity

522 WHITE ET AL.

required for diagnosis in this study. Thus, the prediction does not yet appear to be accurate enough to provide the basis for any intensive intervention program that is designed to prevent stable and pervasive conduct disorder.

The results of the study are also relevant to recent concerns with classification issues in delinquency (Hinshaw, 1987; Moffitt, 1990). Much evidence suggests that delinquency in adolescence appears to be a heterogeneous expression of general maladjustment. Our five preschool predictors showed limited predictive utility at age 15.

One important question for future research is whether delinquent behavior in adolescence that is not preceded by a history of earlier antisocial behavior can be predicted earlier, perhaps by variables that are distinct from those that predict the stable and pervasive cases. There is a need to distinguish better between persisters and newcomers and to take into account the prediction of newcomers between ages 11 and 15.

In this study, a number of individuals in the group comprising subjects with other disorders, emerged as delinquents by age 15, even though they were notable for their lack of antisocial behavior in middle childhood. Among the 13 variables that differentiated among the groups at age 11, 3 did not discriminate between the group with other disorders and the group with antisocial disorders: sleep problems, low IQ, and delayed receptive language. These preschool factors suggest the hypothesis that neuro-cognitive problems appear to be associated with general risk for later childhood and adolescent psychopathology.

Nevertheless, some variables measured during the preschool period did discriminate between the group with other disorders and the group with antisocial disorders, notably the five variables identified in this study. Three variables were behavioral (parent-reported behavior problems at age five, difficult to manage at age three, and externalizing behaviors at age three). These three variables represent multiple reporters, child ages, and methods of assessment. The parent’s report of behavior problems was provided by the child’s mother, using a pencil and paper checklist (i.e., the Rutter Behavior Problem Scale A), when the child was five years old. The externalizing behaviors data were obtained through a checklist completed by two research staff (a psychometrist and a pediatrician), who observed the child for about one hour at age three. The difficult-to-manage measure was the mother’s response to a simple question when her child was three years old, “Has your child been an easy baby or a difficult baby?” All of the reports were prospective and therefore blind to each child’s outcome. The relative superiority of these child behavior descriptors is consistent with earlier reports.

The two motor variables (McCarthy Motor Scales and Draw-A-Man at age five) were unexpected predictors. Perhaps they may serve as early indices of the hyperactive syndrome. When hyperactivity is found in combination with antisocial disorders, it has been shown to have implications for a variety of


functional areas, including cognitive abilities, behavior, family relations, and learning disabilities (Hinshaw, 1987; Moffitt, 1990).

An important point is that the archival variables we examined varied widely in such psychometric properties as distribution, width of range, and reliability. These factors may have influenced the ability of individual measures to detect group differences. In general, the five variables that did discriminate were among the more reliable measures. However, some of the most psychometrically robust variables, such as the Stanford-Binet IQ or the Vineland Social Maturity Scale (see appendix), were not better predictors than informal maternal reports on child characteristics such as “difficult to manage” or “number of disobedient behaviors yesterday.” Nevertheless, it is extremely important to keep in mind the need for developing sound measurement techniques for prediction studies.

In summary, it appears that some preschool predictors can be strong statistical predictors of later antisocial outcome. Due to the high rate of false posi- tives among those children predicted to have antisocial outcomes, the usefulness of preschool behavioral predictors for selecting children for intensive early intervention efforts may be limited at present. The predictive accu- racy of behavioral variables may be improved with the use of other variables from different domains measured during the preschool period. Further research is needed to explore this possibility.

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Jennifer White is a doctoral candidate in the clinical psychology program at the Univer- sity of Wisconsin at Madison. Her research interests include the study of risk and protective factors in the development of antisocial behavior.

Terrie Moffitt is Associate Professor of Psychology at the University of Wisconsin at Madison. She is a research and clinical psychologist arid is principal investigator of projects with the Pittsburgh Youth Study and the Dunedin Multidisciplinary Health and Development Study in New Zealand. Her research interests are in the natural history of antisocial behavior and relations between personality and behavior pathology.

Felton Earls, a child psychiatrist and epidemiologist, is Professor of Human Behavior and Development at Harvard School of Public Health and Professor of Child Psychiatry at Harvard Medical School. He is Director of the Program on Human Development and

528 WHITE ET AL.

Criminal Behavior, a project whose long-term goals are to conduct longitudinal studies on crime and related antisocial behavior.

Lee Robins’s first study of the long-term effects of antisocial behavior was reported in Deviant Children Grown Up. She has continued to explore the adult implications of early behavior problems in studies of inner city black men, Vietnam veterans, and the general population. She is Professor of Sociology in Psychiatry at the Washington University School of Medicine.

Phil A. Silva is the Director of the Dunedin Multidisciplinary Health and Development Study in New Zealand. He began the longitudinal study in 1971 and is one of New Zea- land’s foremost experts in child health and development.


APPENDIX PRESCHOOL PREDICTOR VARIABLES

TESTED FOR RELATION TO ANTISOCIAL DISORDERS

HEALTH VARIABLES

(1-3) Age (in Months) at Which Children First Spoke in Words, Walked Independently, and Talked in Sentences (Assessed at Age three). In New Zealand, new mothers are given a recordkeeping book in which they track their child‘s development. All mothers receive several home visits from a public health nurse, who encourages the mother to keep good records. The dates when the child began to walk, speak in words, and use full sentences were taken from the booklets. When the booklets were not available (66% of the mothers had books), the mothers were asked to try to recall the child’s age in months for each milestone. Responses were recorded only if the mother was certain when the milestone occurred. (See Silva et al., 1982.) (First Words (months): M = 16.72, S.D. = 6.14, range = 0-44, N = 888. First Walked (months): M = 13.74, S.D. = 3.54, range = 044, N = 1,025. First Sentence (months): M = 25.18, S.D. = 6.46, range = W, N = 952.)

(4) Fine Motor Skills at Age 3. This score was obtained from the child’s performance of seven fine motor block-building tasks taken from the Stan- ford-Binet Intelligence Scale (Terman and Merrill, 1960. A higher 1960 score indicates better performance. (M = 6.36, S.D. = 1.04, range = 0-7, N = 1,014.)

( 5 ) Bayley Motor Skill at Age 3. Motor coordination was assessed at age 3 by trained pediatricians using the 28 most difficult motor items from the Bay- ley Scales of Infant Deve1opmer.t (Bayley, 1969). Examples of items used are “Hops on left foot 5 or more times” and “Jumps over 12 inch string.” For information regarding the use of the Bayley in the New Zealand sample, see Silva and Ross (1980). (M 92.77, S.D. = 294.46, range = 0420, N = 944.)

(6) Neurological Signs at Age 3. Each child was examined by a pediatrician for neurological signs, including assessment of motility, passisve movements, reflexes, facial musculature, strabismus, nystagmus, foot posture, and gait. This assessment was based on the procedures described by Touwen and Prechtl (1970); the results have been reported by McGee et al. (1982). A neurological dysfunction score was calculated for each child as an unweighted sum of individual abnormalities. (M = .20, S.D. = 37, range =

(7) The McCarthy Motor Scales, Age 5. At age 5 the Leg Co-ordination Scale of the McCarthy Scales of Children’s Abilities (McCarthy, 1972) was administered and scored directly according to the methods described in the test manual. The Leg-Co-ordination Scale is similar to the Bayley Motor

0-11, N = 977.)

5 30 WHITE ET AL.

Scale; it consists of six items involving walking forward and backward, walking on tip toe, standing on one foot, and skipping. For information regarding the use of the McCarthy in the New Zealand sample, see Silva and Ross (1980). (M = 33.06, SD. = 10.55, range = 0-57, N = 972.)

(8) Sleep Problems at Age 5 . During an interview about the child’s behavior and health, mothers were asked if their child usually experienced serious difficulty with sleeping. (See Clarkson et al., 1985.) (Yes = lo%, No = 90%, N = 1,035.)

(9) Used Health/Social Services 4+ Times per Year, Age 5 . Mothers were asked how often the child had visited each of nine available services in the previous year. The services included clinics, kindergarten for intellectually handicapped children, social welfare, the psychological medicine department, speech therapy, and the pediatric outpatient department. (See Silva et al., 1981). (4 or more = 20.6%, 3 or fewer = 79.4, N = 1,033.)

(10) Hand Preference at Age 5. Observations of handedness were conducted by the examiners during testing at age 5. (Left-handed = 6.5%,

(1 1) Enuresis at Age 5. As part of an interview about their child’s health, mothers were asked whether their child was “dry” yet. (See McGee et al., 1984.) (Dry = 89%, Wet = 11%, N = 1,034.)

Right-handed = 93.5%, N = 677.)

COGNITIVE VARIABLES

(12) The Peabody Picture Vocabulary Test (PPVT), Age 3. The PPVT (Dunn, 1965) provides an estimate of verbal intelligence, without requiring a verbal response mode. The subject is asked to point to one of four pictures in response to a stimulus word. The results of the PPVT have been found to correlate at a moderately high level with IQs obtained from other, more detailed tests, such as the Binet and WISC. In this sample, the PPVT score at age 3 is correlated with the WISC-R at age 11, r = .49. (See Silva, 1985.) (M = 23.52, SD. = 9.57, range = 0-52, N = 979.)

(13-16) Reynell Developmental Language Scales at Ages 3 and 5. These scales (Reynell, 1969, 1977) were used to assess receptive and expressive language function. Receptive language was assessed at ages 3 and 5 by present- ing subjects with toys and asking them to respond to questions of incremental complexity. At the more advanced stages, understanding of abstract or advanced language is called for. Expressive language is assessed with three separate subtests. The first is a checklist of levels of observed language structure. Samples of the subject’s spontaneous language are noted and recorded during testing or during a play period and classified according to the number of words in the subject’s vocabulary, the types of sentences used, whether correct use is made of pronouns and prepositions, and whether correct com- plex sentences are used. The second subtest of the Expressive Language Scale


assesses spoken vocabulary by asking the child to name objects and given definitions of words. The third subtest is a measure of the content of the child’s language. Pictures are presented, the child is asked to tell the exam- iner about them, and the number of separate ideas expressed is counted. Scores are given on the basis of criteria set out in a manual. The three subtest scores are summed to give a total expressive language score. Silva (1986) and Silva et al. (1978) have described reliability and validity information for the scales using the New Zealand sample. (Also, see Silva, 1980a; Silva et al., 1983, 1987.) (Expressive at 3: M = 35.84, SD. = 8.41, range = 0-58, N = 1,028. Receptive at 3: M = 34.84, S.D. = 8.76, range = 0-54, N = 1,028. Expressive at 5: M = 50.22, S.D. = 6.66, range = &59, N = 936. Recep- tive at 5: M = 50.87, SD. = 5.26, range = 0-58, N = 936.)

(17) Draw-A-Man Test, Age 5. This task was administered and scored according to Hams (1963). It can be interpreted as a nonlanguage measure of perceptual and visual-motor integration. (M = 10.32, S.D. = 4.52, range = 0-28, N = 932.)

(18) The Stanford-Binet Intelligence Scale, Age 5. This test (SBIQ, third revision; Terman and Merrill, 1960) includes a variety of tasks designed to measure IQ from age 2 to superior adult level. The latest Binet norms (Thur- stone, 1973) were used to compute a single IQ score. The SBIQ at age 5 correlates with age 11 WISC-R full scale IQ in this sample, r = .62. Anastasi (1961) has reported reliability and validity information for the SBIQ. (M = 105.87, SD. = 16.67, range = 2&159, N = 986.)

(19) Parents Expect Child to be Above-average Pupil, Age 5. When the children were 5, mothers were asked whether they expected their child to be “slow, average, or above average” when the child entered school. (24.6% = above average, 75.4% = remainder, N = 1,023.)

BEHAVIORAL VARIABLES

(20) Externalizing Behaviors (Aggression, Hyperactivity) at Age 3. Rat- ings by three sources were included in the scale. After spending an hour with each child, an observing psychometrist and the examining pediatrician rated him or her on a five-point scale for 15 behavioral style items. The parent also rated the child. The most extreme rating on items pertaining to attention span, activity level, impulsivity, assertiveness, and hostility were summed for this scale. (A4 = .27, S.D. = .75, range = 0-6, N = 1,037.)

(21) Internalizing Behaviors at Age 3. Ratings by two sources were included in the scale. A psychometrist and the examining pediatrician rated each child on a five-point scale for 15 behavioral style items. The most extreme rating on items pertaining to fearfulness, passivity, lack of communi- cativeness, lack of confidence, and tendency to withdraw were summed for this scale. (M = 1.05, S.D. = 1.60, range = 0-9, N = 1,037.)

532 WHITE ET AL.

(22) Percentages of Children Who Were Difficult to Manage at Age 3. Mothers were asked, “How easy is your child to manage at home?” “Very difficult” responses were coded as one for this variable. “Sometimes difficult’’ and “always easy” were coded as zero. (12% = very difficult, 88% = remainder, N = 976.)

(23) Vineland Social Maturity Scale, Age 3. This scale (see Doll, 1953) is a checklist completed by mothers of the child‘s abilities in self-help, dressing, eating, communication, socialization, locomotion, and occupations (e.g., “asks to go to toilet,” “drinks from cup,’’ “plays cooperatively,” and “helps with household tasks”). (M = 45.85, SD. = 29.47, range = 0-95, N = 1,035.)

(24) Childhood Activities, Age 3. A checklist of 30 items was developed that consisted of a wide range of childhood activities (e.g., draws, listens to records, plays in sandbox, has a pet). The mother was asked to check the activities in which her child had participated at home during the first three years of life. The score was the sum of three points for each activity recorded for each child. (See Silva, 1980b.) (M = 49.46, S.D. = 29.67, range = 0-93, N = 1,037.)

(25) Childhood Experiences, Age 3. This was assessed by the use of a checklist consisting of 30 items that covered the range of the child’s experience up to age 3 (e.g., visits zoo, restaurant meal, museum, circus). The score was simply the number of experiences reported by the mother for each child (Silva, 198Ob; Silva and Fergusson, 1976). (M = 41.66 S.D. = 3 1.54, range = 0-92, N = 1,037.)

(26-27) Rutter Child Scale, Age 5. Each parent and teacher was asked to complete the Rutter Child Scales (Rutter et al., 1970). The age-5 version of this questionnaire for parents consisted of 18 items (e.g., worries, disobedient, miserable) comprising a variety of internalizing and externalizing behavioral problems. Responses were coded as “doesn’t apply” (0), “applies somewhat” (l), and “certainly applies” (2). The questionnaire for teachers consisted of 25 items scored in the same way. (Parent RCS: M = 3.52, S.D. = 3.99, range = &23, N = 989, Teacher RCS: M = 6.21, S.D. = 3.73, range = 0-19, N = 985.)

(28) Number of Behaviors Yesterday, at Age 5. As part of a questionnaire about discipline, mothers were asked how many times during the previous day their child was rude, obstinate/disobedient, destrictive, silly/showed off, aggressive (fighting or cruel to animals), demandinglwhininglnagging, made a mess, stole something, told a lie, did anything dangerous, or made a nui- sance by being overactive. These frequencies were summed. (M = 6.59, SD. = 7.30, range = 0-87, N = 1,028.)

(29) Delays Obeying Parents, at Age 5 . As part of the discipline interview, mothers were asked, “How soon does your child usually obey you?” Possible


responses were “fairly quickly, have to keep at himher, or sometimes quickly but sometimes not.” The response “have to keep at h i d e r ” was scored positively for this variable. (37.1% = “have to keep at him,” 62.9% = remainder, N = 561.)

(30) Attention Span Less Than 10 Minutes, at Age 5. Mothers were asked, “1s your child’s typical span of attention and concentration on one activity . . . less than 10, 10-20, 20-30, or longer than 30 minutes?” “Less than 10 minutes” was scored positively for this variable. (22.6% = attention < 10 minutes, 77.4% = remainder, N = 1,013.)

(31) Mother Worries about Behavior, at Age 5 . As part of an interview regarding the child’s behavior, mothers were asked whether they had any specific worries or concerns regarding their child’s behavior. Responses were coded as yes or no. (3% = yes, 97% = no, N = 1,035.)

(32) Rejecting/Demanding versus Shy Personality, at Age 5 . As part of an interview about the child‘s behavior, mothers were asked to describe their child‘s personality. Responses were coded as “distant, rejecting, demanding” (0), “shy, withdrawn” (l), or “bright, pleasant, relates easily to people” (3). (5.9% = rejecting/demanding, 35.2% = shy, 58.9% = pleasant, N = 957.)

(33) 3 + Tantrums in Past 6 Months, Age 5. As part of a questionnaire concerning parental discipline practices, mothers were asked about the number of tantrums their child had experienced during the past 6 months. A tantrum was defined by the interviewer as “total loss of control with contin- ual screams and violent movements”. (8.9% = 3 + tantrums, 91.1% = remainder, N = 1,034).

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HOW EARLY CAN WE TELL?: PREDICTORS OF CHILDHOOD CONDUCT DISORDER AND ADOLESCENT DELINQUENCY