It again has been my pleasure to work with an outstanding group of contributors in the production of this, the 9th Annual Research Review. In inviting contributions, the intention is that authors provide selective reviews that will serve to update the readership on current research and emerging research trends. As always I am grateful to the authors for agreeing to undertake these reviews, as well as to the referees whose thoughtful and detailed comments to the authors enrich each of the papers. As noted in last year's Editorial, this, and future issues, will begin to revisit some of the topics addressed in previous reviews.

In this issue Susan Gathercole has provided a thoughtful discussion of the issue of development of memory in children. As she notes, many changes take place in the development of children's capacities for memory, particularly in the pre-school years. These topics are of interest to clinicians and researchers working with children. Jan Wallander and James Varni have undertaken a review of the effects of chronic physical disorder on the development of children and their families. As noted, recent research has helped to identify risk and protective factors although evaluations of interventions, sadly, remain lagging. Three papers in this issue are more directly focused on clinical disorders. Maria Kovacs and Bernie Devlin review the topic of internalising disorders in children. This paper focuses on aspects of predictive validity, comorbidity, onset, and family history. Rosemary Tannock reviews recent advances in our understanding of the neurobiology of attention deficit hyperactivity disorder; her review highlights the range of problems observed in this condition and the need for interdisciplinary research perspectives. Leslie Jacobsen and Judith Rapoport provide a most helpful summary of recent work on childhood schizophrenia. Although this condition is very rare, its tremendous cost in human terms as well as its significance for research lends considerable interest to this review. Research on both these conditions has considerable potential in helping understand aspects of syndrome pathogenesis and mechanisms of disorder. Finally, Edmund Sonuga-Barke has undertaken a review of the issue of categorical approaches to classification of childhood disorders with particular focus on the implications for clinical practice and diagnosis that arise as alternative models for such classification schemes are assessed.

For the 10th edition of the Annual Research Review, we anticipate that the following topics will be covered: effects of trauma on children, advances in the genetics of childhood psychiatric disorders, effects of divorce on children, comorbidity of mental health disorders, the development of language, and neuroimaging.

This article reviews recent advances in understanding the changes in memory function that take place during the childhood years. Development of the following aspects of memory are considered: short-term memory, comprising phonological memory, visuospatial memory, and executive function; autobiographical memory; episodic memory, including eyewitness memory; and metamemory. Each of these aspects of memory function shows substantial qualitative change from infancy, through the preschool period, to the early school years. Beyond about 7 years of age, however, memory function appears adult-like in organisation and strategies, and shows only a gradual quantitative improvement through to early adolescence.

Research conducted primarily over the past 5–8 years on the psychosocial effects of pediatric chronic physical disorders on children and their families is reviewed. A large body of studies show that both children and their mothers, as groups, are at increased risk for psychosocial adjustment problems compared to peers, but that there is considerable individual variation in outcome. Since the last review on this topic (Eiser, 1990a), many studies have been conducted to identify risk and resistance factors associated with differences in adjustment among these children and their mothers. Improvements are noted in the theoretical basis for this work, programmatic nature of some of the research, and efforts at producing clinically relevant information. Evaluations of interventions, however, are lagging. Critical issues and future directions regarding developmental approaches, theory, method, measurement, and intervention are discussed.

In this selective review of recent research on internalizing disorders in childhood, we focus on four areas: the predictive validity of the diagnoses of depressive and anxiety disorders, rates of comorbidity, the chronology of onsets of the disorders of interest, and transmission of depressive and anxiety disorders in the pedigrees of affected individuals. To synthesize and reconcile findings in these four areas, we approach the information from a developmental perspective and assume that genetically driven biologic processes play a salient role in the expression of depressive and anxiety disorders in childhood. We also comment on the relevance of findings on children and adolescents to the field of depressive and anxiety disorders in adults and make recommendations for further research.

Conceptual and technological advances in cognitive neuroscience and molecular genetics have the potential to identify the pathogenesis of psychiatric disorders. This article reviews the application of these technologies to the scientific study of attention deficit hyperactivity disorder. It begins with a summary of shifts in conceptualization and scientific study of this common condition. This is followed by a critical review of findings from recent cognitive, neuroimaging, and genetic studies. The available data do not yet permit an integration across these different levels of enquiry, but implicate problems in response inhibition, dysfunction of frontostriatal networks, and genetic factors in the pathogenesis of this complex behavioral phenotype. The review closes with suggestions for future interdisciplinary research.

Childhood-onset schizophrenia is a rare, clinically severe form of schizophrenia, which is associated with disrupted cognitive, linguistic, and social development well before the appearance of frank psychotic symptoms. This disruption of multiple developmental domains signals the important opportunity these patients present for examining neurodevelopmental and other etiologic hypotheses of schizophrenia. The present research update reviews studies of the phenomenology and neurobiology of childhood-onset schizophrenia conducted since 1994. Findings from these studies indicate that children can be diagnosed with schizophrenia using unmodified DSM-III, -IIIR, and -IV criteria, and that the atypical neuroleptic clozapine is an effective medication for this treatment refractory group. Neuropsychologic and neurobiologic studies generally support continuity with adult-onset schizophrenia, with evidence of more severe premorbid impairment. Longitudinal studies show preliminary evidence of progressive ventricular enlargment and more prolonged deterioration in intellectual function than is seen in the adult-onset disorder. If replicated, these observations, together with the insidious onset of this disorder, would suggest that the pathologic underpinning of childhood-onset schizophrenia is not a single static lesion or event but may be a continuous or multi-event process.

In this review we explore the clinical and scientific status of categorical models of childhood disorder. Three themes are developed. First, the practical origins of standardised category-based diagnostic schemes are examined along with their contemporary philosophical and psychological significance. Next, the impact that these systems have had on the science of child psychopathology is explored. We look at their link to the medical model and the assumption that childhood disorders are categorical, endogenous, and dysfunctional in nature. We argue that these assumptions underpin the dominant paradigm in child psychopathology and so constrain empirical study and theory development. In the final section, the different ways in which researchers have responded to this link and its impact on science are presented. We present the sort of scientific realism associated with Meehl (1995) as the most appropriate basis for a philosophically respectable child psychopathology. Following this approach means unpacking the paradigmatic assumptions, including the assumption of the categorical structure of disorder, into hypotheses that are then put to empirical test. The sorts of data that would allow us to test the categorical hypothesis are identified. We conclude by discussing the results from three recent studies using behaviour genetic analysis of twin data that, in fact, lead us toward a rejection of this hypothesis. The implications for diagnostic and clinical practice of such a rejection are discussed.