Epidemiology of childhood anxiety: longitudinal perspectives

Introduction: Anxiety is cited as one of the most common mental disorders of youth, with serious implications for academic and social outcomes and future psychopathology. Research has increased greatly in the last 25 years but there are still large gaps in our understanding of the descriptive epidemiology of anxiety and the majority of research focuses on the aetiology of adult disorder. The aim of this thesis was to use the best available evidence from studies using a prospective design and diagnostic outcome measures, to understand the onset and trajectory of anxiety through the lifespan and to determine whether childhood anxiety predicts adult anxiety disorders. Method: Principal Investigators from all prospective longitudinal studies of child mental health were approached in order to gain access to diagnostic data relating to anxiety disorders in youth. Two studies released appropriate data which are analysed here to determine prevalence, first onset, and course of anxiety, with adult outcome assessed in the one cohort that released appropriate adult data. These data are then synthesised with the published data in order to provide a coherent summary of the current picture of the descriptive epidemiology of anxiety disorders, in particular social anxiety and generalised anxiety or overanxious disorder. Results: New data from a UK birth cohort show the different anxiety disorders to have specific patterns of prevalence and onset, suggesting early onset for separation anxiety and specific phobia. Analysis of data from New York suggests moderate homotypic continuity of social anxiety and overanxious disorder in childhood and adolescence. When examined together the available data show the importance of methodological considerations when determining the prevalence of anxiety in childhood and suggest that although substantial proportions of children will suffer from anxiety most will be disorders of short duration with favourable outcomes. There are, however, consistently across studies 20-30% with chronic anxiety who are likely to have poor outcomes. It is clear that a substantial proportion of adult sufferers have early onset but the figures are inconsistent across different studies. Discussion: The results are discussed in light of the wider literature, and implications for methodology and clinical applications are presented. The limitations of the current approach and directions for future research are briefly outlined.