Longitudinal Outcome of Youth Oppositionality: Irritable, Headstrong, and Hurtful Behaviors Have Distinctive Predictions

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1 Longitudinal Outcome of Youth Oppositionality: Irritable, Headstrong, and Hurtful Behaviors Have Distinctive Predictions ARGYRIS STRINGARIS, M.D., M.R.C.PSYCH., AND ROBERT GOODMAN, PH.D., F.R.C.PSYCH. ABSTRACT Objective: Oppositional behavior in youths is one of the strongest predictors of a wide range of psychiatric disorders. We test the hypothesis that oppositionality encompasses an Irritable, a Headstrong, and a Hurtful dimension, each with distinct predictions. Method: Longitudinal design combining data from two British national surveys and their respective 3-year follow-ups (N = 7,912). The Developmental and Well-Being Assessment was used to generate DSM-IV diagnoses. Results: The Irritable dimension was the sole predictor of emotional disorders at follow-up and was particularly associated with distress disorders (depression and anxiety) rather than fear disorders (phobias, separation anxiety, and panic disorder), both before and after adjustment for baseline psychopathology. The Headstrong dimension was the only predictor of attention-deficit/hyperactivity disorder at follow-up. Both Headstrong and Hurtful predicted conduct disorder, although only the Headstrong dimension did so after adjustment for baseline psychopathology. The Hurtful dimension was the strongest predictor of aggressive conduct disorder symptoms. Conclusions: Our data suggest a developmental model of mental disorder whereby oppositionality is an interim shared manifestation of different dimensions of psychopathology with distinct outcomes. J. Am. Acad. Child Adolesc. Psychiatry, 2009;48(4):404Y412. Key Words: oppositional defiant disorder, depression, comorbidity, emotional disorders, attention-deficit/hyperactivity disorder. Oppositional behavior occupies a central position in developmental psychopathology. Classified under the disruptive behavior disorders in DSM-IV, 1 the diagnosis of oppositional defiant disorder (ODD) shows continuity with conduct disorder (CD) 2,3 and substantial overlap with attention-deficit/hyperactivity disorder (ADHD). 4Y6 However, ODD also shows strong associations with emotional disorders in clinical 7 as well as epidemiological 5,6 samples. This wide range of associations of oppositionality with other disorders is also reflected in the finding that it is one of the most common Accepted November 17, Both authors are with the King s College London Institute of Psychiatry. The study was funded by the British Department of Health. Correspondence to Argyris Stringaris, M.D., M.R.C.Psych., Section on Bipolar Spectrum Disorders, Emotion and Development Branch, Mood and Anxiety Program, National Institute of Mental Health, Building 15K, MSC-2670, Bethesda, MD ; stringarisa@mail.nih.gov /09/ Ó2009 by the American Academy of Child and Adolescent Psychiatry. DOI: /CHI.0b013e f30 precursors for most psychiatric disorders in adolescence and young adulthood. 8,9 These findings suggest that ODD may encompass symptom dimensions that go beyond what one would typically expect for disruptive disorders. Motivated by prior theory, 7 some empirical findings, 10 and clinical experience, we recently investigated the a priori hypothesis that oppositionality is composed of three dimensions, each with distinct morbid associations. 11 Using a large cross-sectional epidemiological sample, we have shown that oppositionality could be fractionated into an Irritable dimension that is most strongly associated with emotional disorders, a Headstrong dimension that is particularly associated with ADHD, and a Hurtful dimension that is primarily linked to the aggressive symptoms of CD. 11 These findings raised the possibility that the three dimensions within oppositionality may reflect heterogeneity in etiology, pathophysiological mechanisms, prognosis, and treatment choice. However, these differential associations were derived from a cross-sectional sample, requiring particular caution J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL 2009

2 OUTCOMES OF OPPOSITIONALITY when attempting to draw causal inferences. This calls for the investigation of these differential associations using longitudinal designs. The present manuscript uses a 3-year follow-up sample of children and adolescents in the community to test a range of hypotheses related to the existence of three dimensions within oppositionality. First, we hypothesize that the Irritable dimension of oppositionality will predict to internalizing diagnoses at 3-year follow-up. We conceive of the Irritable dimensionvthe combination of temper outbursts, anger, and a low threshold for being annoyedvas representing negative emotional reactivity and emotion dysregulation. Indeed, it has been shown that children with severe mood dysregulation, a syndrome where negative emotional reactivity is a prominent feature, are more likely to develop depression than a disruptive disorder at follow-up. 12 In accordance with these findings, we expect that the prediction from the Irritable dimension will be particularly pronounced for depression and generalized anxiety. These comprise the so-called distress disorders, 13 a putative category that may be empirically distinguished 14 from so-called fear disorders, that is, specific and social phobias, separation anxiety, and panic disorder. Second, we expect the Headstrong dimensionv composed of symptoms capturing argumentativeness, noncompliance, and rule breakingvto be particularly associated with the diagnosis of ADHD. This would be in keeping with our previous results 11 as well as with the finding that ODD items loaded on a single factor with hyperactive and impulsive items in factor analysis. 10 Third, we hypothesize that all three dimensions will predict to the diagnosis of CD at outcome; however, we expect that the Hurtful dimensionvcomposed of items capturing spitefulness and vindictivenessvwill be particularly predictive of the aggressive symptom domain of CD. METHOD Epidemiological Sample Two different cross-sectional surveys of the mental health of representative samples of British children and adolescents were performed by the Office for National Statistics 6,15 in 1999 and 2004, obtaining a combined sample of 18,415 subjects aged 5 to 16 years. The design of British Child and Adolescent Mental Health Survey 1999 is described in references, 6,15,16 and that of British Child and Adolescent Mental Health Survey 2004 is described in reference. 15 Briefly, in Great Britain, Bchild benefit[ is a universal state benefit payable for each child in the family, and it has an extremely high uptake. The child benefit register was used to develop a sampling frame of postal sectors from England, Wales, and Scotland that, after excluding families with no recorded postal code or subject to current revision of their record, was estimated to represent 90% of all British children. Follow-up took place 3 years after the original survey, that is, in 2002 for the 1999 sample and in 2007 for the 2004 sample. 16,17 Resources did not permit full followup of both samples: a random sample of 10,574 families were approached (stratified for initial diagnosis), of whom, 75% participated, generating a sample of 7,912 children and adolescents aged 8 to 19 years. Hereafter, baseline refers to the combined 1999 and 2004 samples, and follow-up refers to the combined 2002 and 2007 samples. Measures The Strengths and Difficulties Questionnaire (SDQ) is a 25-item questionnaire with robust psychometric properties. 18Y20 It was administered to parents and scored in the standard manner to generate the conduct, emotional, and hyperactive-inattentive scores used as covariates in some of the analyses presented here. The Development and Well-Being Assessment (DAWBA) was used in both surveys and has been extensively described previously. 6,21,22 It is a structured interview administered by lay interviewers who also recorded verbatim accounts of any reported problems. The questions are closely related to DSM-IV 1,23 diagnostic criteria and focus on current rather than lifetime problems. The DSM-IV diagnoses were used throughout in this manuscript. The. statistic for chance-corrected agreement between two raters was 0.86 for any disorder (SE 0.04), 0.57 for internalizing disorders (SE 0.11), and 0.98 for externalizing disorders (SE 0.02). 6 In line with DSM stipulations, children were only assigned a diagnosis if their symptoms were causing significant distress or social impairment. The DAWBA interview was administered to all parents and to all children aged 11 years or older; a shortened version of the DAWBA was mailed to the child s teacher. Additional information on the DAWBA is available from including online and downloadable versions of the measures and demonstrations of the clinical rating process. To keep the interview as brief as possible, the DAWBA makes use of Bskip rules[ that allow interviewers to omit many of the detailed questions in a section when answers to preliminary questions indicate a low probability of disorder in that domain. In the case of the section for the parental report on ODD, the parents are not asked any of the items on ODD unless the parent-based SDQ conduct score is in the top 20% for a community sample, or in answer to a screening question, the parent reports that the child s behavior is more troublesome than that of other children of the same age. The initial validation of the DAWBA demonstrated that this procedure allows 76% of community cases to skip the questions on ODD at relatively low costvof the ODD cases diagnosed in the absence of skip rules, 94% were still diagnosed when the skip rules are in place. 6 In the present study, approximately 23% (4,278/18,415) of the parents of 5- to 16-year-olds got past the skip rules to answer the detailed questions on oppositional and conduct symptoms. Of these, 1,833 were included in the random subsample who were followed up 3 years later. The DAWBA asks about nine separate symptoms of ODD: one question on each of the first seven DSM-IV items and two separate J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL

3 STRINGARIS AND GOODMAN questions on the eighth DSM-IV item, asking about spiteful and vindictive behavior separately. The ODD items were split as follows into the three a priori specified categories listed below. Each question was introduced with the stem: BOver the last 6 months, and as compared with other children of the same age, has she/he ofteni[ and followed by the specific clause. Irritable had temper outbursts? been touchy or easily annoyed? been angry and resentful? Headstrong argued with grown-ups? taken no notice of rules, or refused to do as she/he is told? seemed to do things to annoy other people on purpose? blamed others for his/her own mistakes or bad behavior? Hurtful been spiteful? tried to get his/her own back on people? (this is a colloquial British expression for vindictive behavior). The response categories for each item were Bno more than others[ (scored 0), Ba little more than others[ (scored 1), and Ba lot more than others[ (scored 2). In accordance with previous investigators, 2,23 we generated three CD subscales for the purposes of some analyses, namely: aggressive CD symptoms (bullying, fighting, weapon use, cruelty to people, cruelty to animals, stealing with confrontation, and forced sex), status violations (staying out late, running away, and truancy), and nonaggressive CD symptoms (firesetting, vandalism, breaking in, lying, and stealing without confrontation). Statistical Analysis Samples in analysis. The sample characteristics are shown in Table 1 and Figure 1. Most of the analyses were done on those subjects (n = 1,833) who had been assessed in sufficient detail at baseline to generate Irritable, Headstrong, and Hurtful scores and who were reassessed 3 years later. As can be seen from Table 1, this group had higher rates of disorders (particularly externalizing disorders) at baseline and follow-up than the sample as a wholevthis is not surprising because the reason that they were assessed with the detailed battery of questions on oppositional and conduct problems is that they scored in the top quartile on the preliminary behavioral screening items. Analyses predicting different sorts of conduct problems at follow-up were done on a subset of 1,017 subjects. The subjects were in the top quartile at both baseline and follow-up and therefore had the detailed behavioral measures on both occasions. As expected, a group defined by being in the top quartile on both occasions had even higher rates of disorders (particularly externalizing disorders) at baseline and follow-up. Logistic regression was used to predict to each of the follow-up diagnoses. Three models were used, adjusting for successively more comprehensive covariates: the Bunadjusted[ models included the three dimensions of oppositionality at baseline as the independent variables, covarying only for age and sex; the Badjusted for baseline diagnosis[ models additionally adjusted for the relevant diagnosis at baseline, for example, adjusting for initial CD as well as age and sex when predicting to CD at follow-up; the Badjusted for baseline score[ models adjusted for the relevant continuous scale of the SDQ at baseline, for example, adjusting for the initial SDQ conduct score as well as age and sex when predicting to CD at follow-up. When predicting separately to distress and fear disorders, it was possible to adjust for baseline diagnosis but not score (there were no separate distress and fear scores). A similar approach was used when predicting to the three symptom dimensions of CD (aggressive, status violations, and nonaggressive), using negative binomial regression because the symptom dimensions were overdispersed count data (variance much larger than the mean). These analyses could be adjusted for baseline score but not diagnosis (the dimensions did not correspond to separate diagnoses). In addition to using p values for determining the contribution of each dimension of oppositionality to the overall model, we also used information criteria for multimodal inference in identifying parsimonious models. 24 The Akaike Information Criterion (AIC) and the Bayesian Information Criterion were used for this purpose. For a given model with N number of observations, k number of free parameters to estimate, and L as the maximized value of the TABLE 1 Sample Characteristics at Baseline and Follow-up n Age (SD) Male ODD CD ADHD ED Characteristics at baseline Total sample 18, (3.3) Sample for testing prediction from baseline ODD3D to diagnoses at follow-up 1, (3.3) Sample for testing prediction from baseline ODD3D to conduct symptoms at 1, (3.1) follow-up Characteristics at 3-y follow-up Total sample 7, (3.3) Sample for testing prediction from baseline ODD3D to diagnoses at follow-up 1, (3.3) Sample for testing prediction from baseline ODD3D to conduct symptoms at follow-up 1, (3.1) Note: The characteristics of the sample at baseline and follow-up are shown. All figures are percentages of the total with the exception of age, which is given in number of years with SDs in brackets. ADHD = attention-deficit/hyperactivity disorder; CD = conduct disorder; ED = externalizing disorders; ODD = oppositional defiant disorder; ODD3D = the three dimensions of oppositionality J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL 2009

4 OUTCOMES OF OPPOSITIONALITY Fig. 1 Schematic representation of sampling and analytic strategy. Broken lines represent sampling, participation, or assessment filtered by skip rules. Solid arrows represent the direction of predictions in the analyses presented in this article. ODD3D = the three dimensions of oppositionality; SDQ = the Strengths and Difficulties Questionnaire. likelihood function, the AIC is defined as AIC = 2k j 2ln(L), and the BIC is defined as BIC = j2ln(l) + ln(n)k. When comparing models, those with the lowest AIC and BIC values are given preference. Given the arbitrary constants and sample size dependence contained in the AIC, a useful rescaling is $ i = AIC i j AIC min, where $ i represents the amount of information lost if a model g i is fit rather than the optimal (or full) model g min. Therefore, positive values on the $AIC imply loss of information. A rule of thumb is that models with $ i of 2 or lower have substantial evidence in their favor, those with 4 e $ i <7 have considerably less support, and those with $ i of greater than 10 have no support. 24 We proceeded as follows to identify the most parsimonious models: first, the AIC and BIC were calculated for the full model with the three dimensions of oppositionality as independent variables covaried for age and sex predicting to a diagnostic outcome (the dependent variable). Then, the AIC and BIC values were calculated for each case when one of the three dimensions were dropped from the model, and these were compared with the full model. In a final step, the two dimensions of oppositionality with the weakest estimates were dropped together from the model and compared with the full model. The same was done using the diagnostic or continuous measures of psychopathology as covariates. Parameters were considered important to the model if, after dropping them, the $ i is lower or equal to 2, and the BIC value was higher than the full model. Given the relatively high intercorrelation between the three dimensions of oppositionality, we calculated the variance inflation factor (VIF) 25 to confirm that the regression models used were not degraded by multicollinearity. The maximum value in our models was 2.82 (mean 2.51); models are deemed uninterpretable when VIF values reach All analyses were done in STATA 10 (Stata Corp, College Station, TX; 2007). Ethical approval. The Institute of Psychiatry granted ethical approval for the clinical rating and secondary analysis of data from the British Child and Adolescent Mental Health Survey (reference 255/99). RESULTS The characteristics of the sample at baseline and at follow-up are shown in Table 1 and Figure 1. In our sample, ODD had a high internal reliability of! =.92. The correlation between the three dimensions were as follows: Irritable with Headstrong, r = 0.78; Irritable with Hurtful, r = 0.63; Headstrong with Hurtful, r = 0.65; all correlations were highly significant ( p <.001). As shown in Table 2, only the Irritable dimension of oppositionality at baseline was a significant predictor of internalizing disorders at follow-up, even after adjusting for age, sex, and either an internalizing disorder or the SDQ emotional score at baseline. The J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL

5 STRINGARIS AND GOODMAN TABLE 2 Dimensions of Oppositionality and Their Association With Diagnoses Internalizing Disorders ADHD Conduct Disorder Irritable Unadjusted 2.33*** (1.63Y3.34) (0.93Y2.17) (0.79Y1.73) Adjust for baseline 1.77*** diagnoses (1.21Y2.57) (0.69Y1.85) (0.69Y1.58) Adjusted for 1.54*** baseline score (1.05Y2.27) (0.81Y1.93) (0.74Y1.71) Headstrong Unadjusted *** 2.54*** (0.61Y1.32) (2.08Y5.11) (1.68Y3.84) Adjust for baseline *** 2.12*** diagnoses (0.62Y1.39) (1.13Y3.14) (1.38Y3.26) Adjusted for *** 1.60*** baseline score (0.64Y1.42) (1.35Y3.41) (1.02Y2.51) Hurtful Unadjusted ** (0.84Y1.60) (0.69Y1.36) (1.14Y2.18) Adjust for baseline diagnoses (0.91Y1.79) (0.76Y1.71) (0.93Y1.84) Adjusted for baseline score (0.81Y1.58) (0.61Y1.25) (0.81Y1.63) Note: In all models, the three dimensions of oppositionality were independent variables covaried for age and sex. Models were either unadjusted or adjusted for either baseline diagnoses or baseline psychopathology score. Odds ratios; 95% confidence intervals in parentheses. ADHD = attention-deficit/hyperactivity disorder. *p <.05; **p <.01; ***p <.001; statistically significant results are highlighted in bold (n = 1,833). Headstrong and Hurtful dimensions did not add to this prediction. In Table 3, we show that the same pattern of results emerges when, instead of considering p values, model fit indices are used to determine the most parsimonious of competing models. Dropping the Irritable term would lead to a substantial reduction of fit as judged by the $AIC value of well above 2 and the BIC values. This applies to the unadjusted as well as to the adjusted model (Table 3). Conversely, dropping either or both of the other two dimensions from the model did not lead to a worse fit. Subsidiary analyses examined whether this effect applied equally to both of the two main categories of internalizing disorders, namely distress disorders and fear disorders, as shown in Table 4. Only the Irritable dimension of oppositionality predicted to distress disorders (depression and generalized anxiety disorder) both before and after adjustment for distress disorders at baseline. None of the dimensions of oppositionality predicted to fear disorders. As shown in Table 2, the Headstrong dimension was the only statistically significant predictor of ADHD, even after adjusting for age, sex, and either ADHD or the SDQ hyperactivity-inattention score at baseline. Table 3 shows that this pattern is also reflected when model selection information criteria are used. Dropping Headstrong, but not any of the other two dimensions alone or in combination, would lead to a substantial worsening of fit of the model. The Headstrong and the Hurtful dimensions (but not the Irritable dimension) predicted CD 3 years later after adjusting for age and sex. However, only the Headstrong dimension predicted to CD after further adjusting either for a diagnosis of CD or for the SDQ conduct score at baseline. Table 3 confirms that, for the unadjusted model, both Headstrong and Hurtful are important for the prediction of CD; however, as demonstrated in Table 3, when adjusting for baseline CD, only the Headstrong dimension seems important. Table 5 shows the results from negative binomial regression analyses predicting to each of the three different symptom domains for CD (aggressive, status violations, and nonaggressive) at outcome. In both the unadjusted and the adjusted models, the Hurtful dimension shows the strongest coefficients for prediction to aggressive symptoms of CD. However, the Headstrong dimension was also a significant predictor of aggressive symptoms, and the difference in size between the Hurtful and Headstrong dimensions diminished in the adjusted model. Moreover, fit indices applied in the same way as for the outcome diagnoses in Table 3 revealed that none of the three dimensions could be dropped without worsening model fit. The Headstrong dimension of oppositionality had the strongest association with status violations and was the only significant predictor in both the adjusted and unadjusted models. However, assessment using the model fit indices revealed that the Hurtful, but not the Irritable, dimension was also an important parameter in the unadjusted and adjusted models. The Headstrong dimension of oppositionality had the strongest coefficients of association with nonaggressive symptoms, although J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL 2009

6 OUTCOMES OF OPPOSITIONALITY TABLE 3 Fit Indices for the Logistic Regression Models Predicting to Disorders Fit Index Full Model Drop Irritable Drop Headstrong Drop Hurtful Drop Two Unadjusted Internalizing disorders $ i BIC V 1, ,166 j2 1,146 j1 1,147 j3 1,139 ADHD $ i V j1 22 j2 j1 BIC Conduct disorder $ i V j BIC Adjusted Internalizing disorders $ i V 6 j2 0 j2 BIC 1,095 1,096 1,088 1,090 1,082 ADHD $ i V j1 5 j1 j2 BIC Conduct disorder $ i V j BIC Note: The tables provide the model fit indices for the logistic regression models predicting to disorders, unadjusted and adjusted for each respective diagnosis at baseline. Models in which one of the indicated terms (e.g., drop Irritable) or the two least important (e.g., Headstrong and Hurtful in the internalizing disorder rows) are compared with the full model, which contains all three dimensions of oppositionality. $ i values that are zero or negative indicate a good model fit, whereas those with positive values over 4 indicate worse fit. BIC values of alternative models that are smaller than the full model indicate better fit and larger values worse fit. Those dimensions whose omission would lead to worse fit are highlighted in bold letters. ADHD = attention-deficit/hyperactivity disorder; BIC = Bayesian Information Criterion. TABLE 4 Distress and Fear Disorders and Their Association With the Irritable Dimension of Oppositionality Distress Disorders Fear Disorders Irritable Unadjusted 3.34*** 1.52 (2.08Y5.38) (0.88Y2.62) Adjust for baseline diagnoses 2.82*** V (1.72Y4.62) V Headstrong Unadjusted (0.39Y1.2) (0.62Y1.97) Adjust for baseline diagnoses 0.69 V (0.40Y1.18) V Hurtful Unadjusted (0.81Y1.86) (0.66Y1.78) Adjust for baseline diagnoses 1.22 V (0.79Y1.88) V Note: In all models, the three dimensions of oppositionality were independent variables in all models, covaried for age and sex. Models adjusted for baseline diagnoses included the respective diagnosis at baseline as a covariate. Odds ratios; 95% confidence intervals in parentheses. *p <.05; **p <.01; ***p <.001; statistically significant results are highlighted in bold (n = 1,833). Hurtful was also significant in the unadjusted models. Both the Hurtful and Headstrong, but not the Irritable, dimensions were important parameters, as assessed using model fit indices. DISCUSSION The findings from this large community study confirm our hypothesis that our three a priori dimensions of oppositionality have different longitudinal psychiatric outcomes even after adjustment for baseline psychopathology, thus extending our previous crosssectional findings. 3 We established these findings using standard p valueyguided criteria, which we confirmed using model fit indices. We expected the Irritable dimension of oppositionality to predict internalizing disorders at outcome. More specifically, we hypothesized that, within internalizing disorders, it would predict to the so-called distress disorders, that is, depression and generalized anxiety. The separation between distress and fear disorders has received considerable support from factor analysis 13,14 and has been proposed as a subcategorization of internalizing disorders. It has been suggested that distress and fear disorders have separate temperamental origins, 14 whereas the genetic correlations between J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL

7 STRINGARIS AND GOODMAN TABLE 5 Dimensions of Conduct Disorder Predicted by the Three Dimensions Aggressive Nonaggressive Status Violations Irritable Unadjusted 0.90 j (j0.15 to 0.34) (j0.19 to 0.12) (j0.092 to 0.39) Adjust for baseline score 0.07 j (j0.16 to 0.31) (j0.19 to 0.12) (j0.097 to 0.39) Headstrong Unadjusted 0.38** 0.36*** 0.42** (0.13V0.63) (0.19V0.52) (0.17V0.67) Adjust for baseline score 0.26* 0.20* 0.36** (0.01V0.51) (0.04V0.37) (0.11V0.61) Hurtful Unadjusted 0.60*** 0.25* 0.11 (0.37V0.82) (0.11V0.39) (j0.11 to 0.33) Adjust for baseline score 0.29* (0.06V0.52) (j0.04 to 0.23) (j0.14 to 0.31) Note: In all models, the three dimensions of oppositionality were independent variables in all models, covaried for age and sex. Models adjusted for baseline diagnoses included the respective diagnosis at baseline as a covariate. Odds ratios; 95% confidence intervals in parentheses. *p <.05; **p <.01; ***p <.001; statistically significant results are highlighted in bold (n = 1,017). depression and generalized anxiety is known to be substantial. 27 Our assumption about the prediction from the irritable dimension to distress disorders is confirmed by the analyses provided here and holds even after adjusting for baseline psychopathology. These findings are also in agreement with the results derived from the study of irritability and negative affect in other community-based studies. Using the Children in the Community dataset, Leibenluft and coworkers 28 devised the construct of chronic irritability that contains temper outbursts and anger items 27 and found that it predicted to depression at 10-year follow-up. Similarly, the construct of severe mood dysregulation that contains negative affect as one of its cardinal features shows continuity with depressive disorder, but not disruptive disorders, in the Great Smoky Mountains study. 12 Therefore, it is tempting to postulate that what is captured by the irritable dimension is a propensity to emotion dysregulation and that this is shared with depression and anxiety disorders. Indeed, recent evidence suggests that lability of mood is common in youths in the general population and that it shows strong associations with depression and anxiety disorders. 29 Future epidemiological and experimental studies may be used to test the commonalities between the negative affect and distress disorders. Our hypothesis was that the Headstrong dimension would be the strongest predictor to ADHD. This hypothesis was confirmed, and Headstrong was the sole predictor of ADHD in both adjusted and unadjusted models. This adds weight to the speculation that ADHD and Headstrong items share joint features originating in delay aversion. 30 However, as we have pointed out before, 11 this only pertains to some, but not all, of the items in the Headstrong dimension. We expected all three dimensions of oppositionality to predict to CD, with the Hurtful dimension as the only predictor of aggressive symptoms of CD. These hypotheses were only partially confirmed. The Headstrong and the Hurtful dimensions were the only predictors of CD in the unadjusted model, and Headstrong was the sole predictor when baseline CD was adjusted for. Whereas the Hurtful dimension was the strongest predictor to aggressive CD symptoms, the Headstrong dimension was also a significant predictor and was not dispensable using model fit criteria. Our previous finding 11 that Headstrong, but not Hurtful or Irritable, was the only statistically significant predictor of status offenses was confirmed in these results. Taken together, these results suggest that the Headstrong dimension is the most important predictor of antisocial behavior overall, with the Hurtful dimension seeming to predict more specifically to aggressive offenses. We have previously hypothesized that the Hurtful dimension may be closely linked to the callous, premeditated, and aggressive aspects of offending. 11 Here, we offer partial J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY, 48:4, APRIL 2009

8 OUTCOMES OF OPPOSITIONALITY confirmation of this assumption. Given that such severe offenses are relatively uncommon in the general population, we expect that testing this hypothesis in high-risk samples will provide further clarification. Although our study was not designed for this purpose, our data may also be of relevance to the longstanding question about the formal relationship between ODD and CD in classificatory schemes. The two are considered separate nosological entities in DSM-IV, 1 whereas International Statistical Classification of Diseases, 10th Revision, 23 classifies ODD as part of CD, and there have been findings highlighting the relative merits and shortcomings of either approach. 3,31Y33 Our findings suggest that there is a heterogeneity within ODD symptom that is reflected not only in the associations with other disorders but also with the relatively different associations within domains of CD symptoms. The results presented here may help explain the puzzling finding that oppositionality is an antecedent of a wide range of adult disorders. In particular, ODD shows not only homotypic continuity to persistent disruptive and antisocial behaviors but also heterotypical continuity to affective problems. 8,9 For this reason, the role of ODD has been described as pivotal in development. 7 Our previous results 3 and the findings presented here suggest that that this may occur because ODD encompasses distinct dimensions. One possible developmental model is that different temperamental traits or environmental stressors converge on ODD as an interim shared outcome before diverging again in their long-term outcomes. This Bconvergencedivergence[ model may prove helpful in addressing the long-standing puzzle of comorbidity in psychiatric disorders 34 in line with the aspirations of DSM-V to provide plausible developmental accounts of psychiatric disorders. 35 These findings may also reflect the need to reevaluate the role of irritability in development and classificatory systems. However, it should be noted that the findings presented here should not necessarily be seen as evidence against the category of ODD. First, only a fraction of those with scores on the dimension scales had a diagnosis of ODD. Second, the symptoms of oppositionality have been shown to have remarkable factorial unity, 32,36 and in our study, they show a high degree of internal consistency. As we have emphasized previously, our three-way division is into three correlated dimensions rather than into three mutually exclusive groups of youth. 11 Finally, our findings do not have a direct impact on aspects such as the important heuristic use of ODD in clinical practice. Our findings also suggest that oppositionality in youths is a complex problem that may require differential clinical interventions according to the predominant dimension. For example, children scoring high on the Irritable dimension may benefit from early interventions to reduce their future risk for distress disorders (depression and generalized anxiety). Similarly, if the Hurtful dimension is related to psychopathy, children scoring high on this dimension may be relatively resistant to standard parenting interventions and therefore require different approaches. 37 Analyzing the three dimensions of oppositionality separately may reveal important differences in genes, brain structure, and brain function. Taken together, our findings strongly favor a view of distinct dimensions within ODD. However, there are several points about our study and the inferences drawn from it that warrant caution. First, the operation of skip rules in the sample means that the measurements for the three dimensions are available on a select medium-risk sample of subjects. Therefore, it will be important to replicate our findings in both low- and high-risk samples to enhance generalizability. Second, the follow-up rate in this large community sample was 75%. Given that, typically, the most severely affected cases are more likely to drop out, we cannot exclude the possibility that this may have influenced our findings. However, it should be noted that the rates of disorder in the follow-up sample did not differ substantially from those of the original sample. Third, the oppositional items that we measured were designed to assess ODD symptoms rather than three distinct dimensions. 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