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Open Access Research article

Epidemiologic heterogeneity of common mood and anxiety disorders over the lifecourse in the general population: a systematic review

Arijit Nandi1, John R Beard234 and Sandro Galea2567*

Author Affiliations

1 Center for Population and Development Studies, Harvard School of Public Health, Boston, USA

2 Center for Urban Epidemiologic Studies, New York Academy of Medicine, New York, USA

3 School of Public Health, University of Sydney, Sydney, Australia

4 Faculty of Health and Applied Science, Southern Cross University, Lismore, Australia

5 Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, USA

6 Department of Epidemiology, Columbia University Mailman School of Public Health, New York, USA

7 Survey Research Center, Institute for Social Research, Ann Arbor, USA

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BMC Psychiatry 2009, 9:31  doi:10.1186/1471-244X-9-31

Published: 1 June 2009

Abstract

Background

Clinical evidence has long suggested there may be heterogeneity in the patterns and predictors of common mood and anxiety disorders; however, epidemiologic studies have generally treated these outcomes as homogenous entities. The objective of this study was to systematically review the epidemiologic evidence for potential patterns of heterogeneity of common mood and anxiety disorders over the lifecourse in the general population.

Methods

We reviewed epidemiologic studies examining heterogeneity in either the nature of symptoms experienced ("symptom syndromes") or in patterns of symptoms over time ("symptom trajectories"). To be included, studies of syndromes were required to identify distinct symptom subtypes, and studies of trajectories were required to identify distinct longitudinal patterns of symptoms in at least three waves of follow-up. Studies based on clinical or patient populations were excluded.

Results

While research in this field is in its infancy, we found growing evidence that, not only can mood and anxiety disorders be differentiated by symptom syndromes and trajectories, but that the factors associated with these disorders may vary between these subtypes. Whether this reflects a causal pathway, where genetic or environmental factors influence the nature of the symptom or trajectory subtype experienced by an individual, or whether individuals with different subtypes differed in their susceptibility to different environmental factors, could not be determined. Few studies addressed issues of comorbidity or transitions in symptoms between common disorders.

Conclusion

Understanding the diversity of these conditions may help us identify preventable factors that are only associated with some subtypes of these common disorders.