It is a great pleasure to write my first editorial, attempting to draw out the clinical relevance of some of the papers in this issue. I think a number of themes emerge in this issue, connected to the enduring problem of inferring underlying processes and problems from behaviour. We all know that behaviour is complex and messy, that the same behaviour may have many different underlying causes, and that the same core difficulty may have different behavioural manifestations in different individuals, at different ages or ability levels. These challenges, and some possible advances, are central to a number of papers in this issue.

HIV and AIDS have made a huge global impact, permeating the social, cultural, and economic fabric of almost all nations. The first cases of HIV infection in children were reported in the late 1980s and numbers have since risen steadily throughout the world, with some of the poorest and least developed countries experiencing the highest prevalence. Combined drug regimes have changed the course of HIV-related illness and brought increased survival to those for whom treatment is available. With this, however, have come fresh concerns relating to drug resistance, treatment adherence, and the risk of second-generation vertical transmission as HIV-infected children now survive into adulthood and beyond. The psychological literature has addressed issues such as the direct effect of HIV on child development, social and cultural attitudes, family functioning and support, affected children and orphans of HIV-infected parents, sexual health education, disclosure of diagnosis, and long-term clinical management. The outcome for those living in wealthier countries is optimistic, but the spread of this virus in the rest of the world and its impact on family life and social and political systems remains of great concern.

This paper reviews the presentation, clinical features, and management of early-onset bipolar disorder. A framework for the treatment is based upon a systematic, critical appraisal of the available literature. A multimodal approach is emphasised using individual and family psychoeducational interventions in conjunction with pharmacotherapy. The role of mood stabilisers—lithium—and the anticonvulsants—sodium valproate and carbamazepine—is reviewed, alongside the treatments for depression in bipolar disorder and refractory mania.

The present study examined psychiatric functioning in a community sample of adolescents aged 14 to 17 years (average age of 15 years). We administered the Diagnostic Interview Schedule for Children-2·25 (DISC-2·25) to 1201 adolescents and their mothers to obtain prevalence estimates of DSM-III-R disorders and the amount of perceived impairment associated with these disorders. While adolescent females reported a significantly higher prevalence of psychiatric disorders than males (15·5% vs. 8·5%), mothers indicated no sex difference. Compared with adolescent males, females had significantly higher rates of internalizing, anxiety, and depressive disorders. In contrast, the prevalence of externalizing disorders was significantly higher among adolescent males. The inclusion of an impairment criterion had a significant impact in reducing the prevalence rates of overall psychiatric disorders. This reduction occurred mainly through impairment's effects on internalizing disorders, specifically anxiety-based disorders (i.e., simple and social phobia). Given the limited research on the effect of impairment on the prevalence of adolescent psychiatric disorders, future work in this area seems warranted.

Epidemiological surveys of child and adolescent mental disorders often rely on multiple informants to get a complete diagnostic picture. A consistent finding in the literature is that different informants often do not identify the same children as being disordered. However, because current strategies for estimating interinformant agreement often involve categorizing children using less than perfectly sensitive and/or specific symptoms, biased estimates of interinformant agreement are likely. The aim of this report was to illustrate how latent class analysis (LCA) can be used to model interinformant agreement in the absence of a “gold standard”. The proposed model consists of informant-specific latent variables each made up of two or more latent classes corresponding to different levels of symptomatology. Unlike most previous applications of LCA this model allows us to model the extent to which the prevalence of the disorder is the same across informants; and, in addition, the association between informants. The data set comes from a prospective longitudinal study of 2264 children from Québec (1155 boys and 1109 girls). In grade 2, teachers and mothers independently rated each child on three physical aggression behavior symptoms. We satisfactorily accounted for the cross-classification of the behavior symptoms by postulating the existence of two latent variables—one for each informant—each made up of three latent classes of children: low-, medium-, and high-aggressive. The results showed that the prevalence of low- and medium-aggressive children in the population differed from teacher to mother, but that the prevalence of high-aggressive children did not. We found that the association between teacher and mother was large and positive and did not vary according to the child's physical aggression state or gender; in contrast, the association between physical aggression and gender was not the same for mother and teacher. Limitations and other potential applications of the proposed model are discussed.

The phenotypic and genetic interrelationships underlying ADHD symptomatology assessed by various instruments were examined on a sample of 735 male and 819 female same-sex twin pairs, aged 8 to 16 years, participating in the first phase of the Virginia Twin Study of Adolescent Behavioral Development (VTSABD). Multivariate analyses were applied to parental and teacher ratings from an investigator-based interview, the CAPA, and three questionnaires (the CBCL and the Rutter Parent and Teacher Scales). Results from patterns of intercorrelations and factor analyses of maternal measures suggested that at the phenotypic level, these assessed the same underlying behavioural construct, which differed from other emotional and behavioural constructs. However, genetic analyses showed that in addition to a common factor underlying the expression of ADHD as assessed across the range of measures, additional genetic factors were identified that were method- and rater-specific. The findings suggest that although the investigator-based interview and the behavioural checklists tap similar aspects of ADHD behaviour, there is additional rater-specific variance.

This study examined patterns of comorbid/associated diagnoses and associated problems in a population sample of children with and without DSM-III-R attention-deficit hyperactivity disorder (ADHD). Half (N = 409) of a mainstream school population of Swedish 7-year-olds were clinically examined, and parents and teachers were interviewed and completed questionnaires. The children were followed up 2–4 years later. Eighty-seven per cent of children meeting full criteria for ADHD (N = 15) had one or more—and 67% at least two—comorbid diagnoses. The most common comorbidities were oppositional defiant disorder and developmental coordination disorder. Children with subthreshold ADHD (N = 42) also had very high rates of comorbid diagnoses (71% and 36%), whereas those without ADHD (N = 352) had much lower rates (17% and 3%). The rate of associated school adjustment, learning, and behaviour problems at follow-up was very high in the ADHD groups. We concluded that pure ADHD is rare even in a general population sample. Thus, studies reporting on ADHD cases without comorbidity probably refer to highly atypical samples. By and large, such studies cannot inform rational clinical decisions.

Several studies have found a relationship between attention-deficit hyperactivity disorder (ADHD) and substance use, primarily in the context of co-occurring conduct disorder (CD). However, very few have examined the associations between the individual dimensions of ADHD (hyperactivity-impulsivity and inattention) and substance use, even though these dimensions reflect distinct symptom groupings, both by clinical definition (DSM-IV, American Psychiatric Association, 1994) and through empirical demonstration (Lahey et al., 1988; McBurnett et al., 1999). This longitudinal study examines the relationship between dimensions of ADHD (as described by DSM) and substance use, accounting for other psychopathology and factors potentially related to substance use. Participants were 177 clinic-referred boys (initially between ages 7 and 12) followed up over nine annual phases until all participants had reached age 15. Annual assessment included structured clinical interviews with parent and child and self-report questionnaires of substance use, as well as questionnaires related to family factors and parenting behaviors. Seventy-eight per cent of participants reported use of tobacco, alcohol, marijuana, or other illicit drugs during adolescence, with 51% reporting any tobacco use. The inclusion of CD rendered all bivariate relationships with the full diagnosis of ADHD nonsignificant. However, adolescent inattention, considered independently, was associated with a 2·2 times greater risk for concurrent tobacco use, even after controlling for CD. Even when other factors, selected based on their associations with tobacco use in adolescence, were included in a regression model (concurrent adolescent CD odds ratio [OR] = 6·08), duration of tobacco use by age 12 (OR = 5·11), poor parental communication in childhood (OR = 2·9), African-American ethnicity (inversely predictive; OR = 0·15), inattention (OR = 2·3) remained significantly associated with tobacco use in early adolescence. These findings highlight the importance of considering the risks for comorbid substance use separately by individual dimensions of ADHD.

The developmental perspective applied to psychopathology has led to the concept of early-and late-onset disorders. This study explores the application of the early- and late-onset concepts of antisocial behavior to physical aggression. Are there two categories of chronically physically violent adolescents: those who are physically aggressive throughout childhood and those who start being physically aggressive during adolescence? The estimation of developmental trajectories for repeated measures of two different response variables—physical aggression in childhood as measured by teacher reports and physical aggression in adolescence as measured by self-reported violent delinquency—is achieved with a semiparametric, group-based method. This new method is applied to a large sample of males from Montreal who have been assessed repeatedly since kindergarten. Several salient findings emerge from the analysis. First, we find considerable change in the levels of childhood and adolescent physical aggression. Thus, there is little evidence of stability of behavior in an absolute sense. A second key finding concerns the connection of childhood aggression to adolescent aggression. Boys with higher childhood physical aggression trajectories are far more likely to transition to a higher-level adolescent aggression trajectory than boys from lower childhood physical aggression trajectories. However, for all childhood physical aggression trajectory levels the modal transition is to a relatively low-level adolescent aggression trajectory. Third, we find little evidence of “late onset” of high-level physical aggression. Specifically, the joint trajectory analysis finds no evidence of transition from a low physical aggression trajectory in childhood to a high trajectory in adolescence.

Based on a sample of 89 aggressive clinic-referred children, aged between 9 and 11 years, a longitudinal study of 1-year duration was conducted to examine (a) whether the children's perception of control and support of their mothers' to them predicted their hostile attribution of intent and hostile response selection, and (b) whether these hostile biased social cognitions mediated the relationships between their perceived maternal behaviours and their aggression. Participants completed a questionnaire covering both the perceived maternal control and support. One year later, their hostile attribution of intent and response selection, and aggression, were measured. Results showed that perceived maternal control and perceived maternal support were associated positively and negatively, respectively, with both the social cognition measures. Also, the social cognition measures mediated the relationships of the perceived maternal measures with aggression. The findings are discussed in terms of how children's hostile biased relational schemas and scripts, developed from negative parenting and insecure attachment, favour more hostile social cognitions, and how these in turn mediate children's current hostile biased social behaviours.

Studies on adults have suggested important effects of stressful life events in provoking onset of psychiatric disorder. Only a few comparable studies on children exist, and their results are inconsistent in relation to definite timing effects. Meeting some important methodological challenges overlooked in the past research, this study set out to examine whether the onset of psychiatric disorder in children was more likely to occur shortly after a severe event, as compared with other times. The sample consisted of 99 consecutive, newly referred patients, aged 8–16 years, from a child psychiatry service in London. PACE (Psychosocial Assessment of Childhood Experiences), an investigator-based, standardized interview was used to assess the timing and impact of life events over the preceding 18 months. CAPA (Child and Adolescent Psychiatric Assessment), a standardized diagnostic assessment, was used to establish the presence, timing, and consequential impairment of child and adolescent psychiatric symptoms. In a within-subject, over-time design, conditional logistic regression techniques were employed to examine whether risk of onset was greater in the 9 weeks following a high-threat life event than at other times. There was a small but statistically significant association between child-reported events and child-reported onset; the associations with parent-reported onset were inconsistent. Parent-reported events failed to relate to onset by either source. The study offers only quite limited support to the notion of negative life events provoking onset of psychiatric disorder in children and young people. The possible reasons for this are discussed, together with important conceptual and methodological issues to problems of defining onset, and the choice of appropriate designs for data analysis.

A 20-event, 7-point scale on the stressfulness of selected unpleasant experiences was administered to 364 children in Grades 4 to 6 in an American intermediate school. Independently, a parallel questionnaire was given to their parents to indicate (a) how upsetting they would find each event themselves, (b) what they estimate their own children's ratings to be, and (c) whether they think their children have actually experienced each event. The parent-child agreements among the 239 responding pairs were quite close on (1) the scale values (the median upsettingness ratings) with an r of .96, (2) the discriminal dispersions (the interquartile ranges of ratings) with an r of .79, and (3) the incidences with an r of .96. The striking contrasts with the earlier comparisons with professional judgements invite a reassessment of parents as dependable observer-reporters.

The current study follows a recent paper reporting that individuals with autism were just as susceptible to visual illusions as those without autism (Ropar & Mitchell, 1999). The possibility that individual differences may account for the failure to replicate Happé's (1996) findings is explored by presenting a battery of visuospatial tasks thought to measure weak central coherence (embedded figures, block design, Rey complex figure test). Participants with autism were distinguished by relatively good performance on visuospatial tasks, though there was no superiority effect in those with Asperger's syndrome. Performance on the visuospatial battery did not significantly predict susceptibility to illusions in various participant groups, including those with autism and Asperger's syndrome. This suggests that perception of illusions and performance on visuospatial tasks may rely on different mechanisms. The implications for the theory of weak central coherence are discussed.

The Tower of Hanoi (ToH) task was given to 238 children aged from 7 to 15 years, and 20 adults. Individual variation within an age band was substantial. ToH score did not correlate significantly with Verbal IQ, nor with ability to inhibit a prepotent response. We readministered the ToH to 45 children after 30 to 40 days. The test-retest correlation of ·5 is low in relation to accepted psychometric standards, though at least as high as reliability of the related Tower of London (ToL) in adults. The reasons for low reliability remain unclear; task novelty did not seem to be involved, as children did not improve on retest. We conclude that it is not safe to use this test to index integrity or maturation of underlying neurological systems in children. We compared our results with three published studies using the ToL with children, and found similar levels of performance on problems involving the same number of moves. Another study using automated ToL obtained much poorer scores, suggesting that computerised presentation may impair children's performance.