Twin Research and Human Genetics

Articles

Symptoms of Anxiety and Depression in Young Adults: Genetic and Environmental Influences on Stability and Change

Ragnhild B. Nesa1 c1, Espen Røysamba2, Ted Reichborn-Kjenneruda3, Jennifer R. Harrisa4 and Kristian Tambsa5

a1 Division of Mental Health, The Norwegian Institute of Public Health, Oslo, Norway. Ragnhild.bang.nes@fhi.no

a2 Division of Mental Health, The Norwegian Institute of Public Health, Oslo, Norway; Department of Psychology, University of Oslo, Norway.

a3 Division of Mental Health, The Norwegian Institute of Public Health, Oslo, Norway; Department of Psychiatry, University of Oslo, Norway.

a4 Division of Epidemiology, The Norwegian Institute of Public Health, Oslo, Norway.

a5 Division of Mental Health, The Norwegian Institute of Public Health, Oslo, Norway.

Abstract

Etiological factors for stability and change in symptoms of anxiety and depression, including sex differences, are largely unexplored in young adults. Using biometric modeling and two-wave longitudinal data from 4393 Norwegian twins aged 18 to 31 we explored (i) heritabilities of symptoms of anxiety and depression, (ii) effects of genetic and environmental factors on the stability and change of such symptoms, and (iii) sex-specific effects. The phenotypic cross-time correlations for symptoms of anxiety and depression were estimated to .54 and .49 for males and females, respectively. The best fitting longitudinal model specified additive genetic and individual environmental influences and emerging effects from the shared environment for females only. For both males and females, long-term stability was mainly attributable to stable additive genetic factors, whereas change was essentially related to environmental influences. Minor time-specific genetic effects were indicated, and some stable variance was due to the individual environment. Additive genetic risk factors explained 87% and 68% of the phenotypic cross-time correlation for males and females, with the unique environment accounting for the remaining covariance. The results provide strong evidence for the temporal stability of genetic risk factors for symptoms of anxiety and depression in young adults, and substantial sex-specific influences on heritability, stability and change.

(Received October 19 2006)

(Accepted February 09 2007)

Correspondence:

c1 Address for correspondence: Ragnhild Bang Nes, Division of Mental Health, The Norwegian Institute of Public Health, Pb 4404 Nydalen, N - 0403 Oslo, Norway.

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