The project follows on from a systematic review of published longitudinal data appertaining to the prevalence, course and onset of anxiety disorders in childhood and adolescence submitted as part of a doctoral thesis to the University of Manchester (Gallagher, 2008). From the limited published data in the field this review concluded that it was likely that many adult anxiety disorders had their onset in childhood and adolescence, and that childhood anxiety was as prevalent as anxiety disorders in adulthood, yet receives only a small proportion of the research attention, despite a lack of specific developmentally appropriate treatment models. Due to the scarcity of published data on diagnosed anxiety disorders in these populations, these conclusions could not be sufficiently substantiated.

The current project has secured access to large longitudinal data sets from Germany and the US that have not yet been fully analysed in terms of prevalence, course and age at onset of anxiety disorders. Once these datasets are fully analysed then this data will be used in a metaanalysis to determine at what age onset of each anxiety disorder is most likely, whether early onset confers greater risk for later disorders, and in samples which have data into adulthood what proportion of adults had their first onset in childhood or adolescence.

The data requested from ALSPAC would therefore include diagnostic status according to the DAWBA at age 7, 10 and 13(14). These data would be analysed to generate prevalence rates, new onset and continuity of disorders across the three follow ups. The combination of mother and child response (if available) will be dictated in part by the methods used in existing data sets as this will then be compared to data from two published data sets and the two data sets that we have analysed. This information will also be statistically combined in order to generate mean prevalence and median age at onset for anxiety disorders across the samples. As the ALSPAC data is currently collected into adolescence it would not be suitable for inclusion in the final metaanalysis examining age at onset of adult disorders. However, this data will add to the current proposal in two major areas. 1) Longitudinal data from Britain was not previously included due to a lack of published data and ALSPAC data will give insight into patterns of the development of anxiety in a British population. 2) Only one of the other studies included has collected data before the age of 11, the inclusion of prevalenc data for seven year olds will add to the understanding of the course from childhood into adolescence.