Genetic and environmental influences on rumination and its covariation with depression.

This study examined the extent to which rumination and depression share genetic and environmental influences in a community sample of adult twins (N=663). Twins completed multiple rumination questionnaires, a depressive symptoms questionnaire and a diagnostic interview. Rumination was moderately heritable (h2=.37-.41 for the latent variable) and substantially influenced by nonshared environmental factors, and these results were consistent across different measures. Nonshared environmental influences on rumination were larger for women than men. Depressive symptoms and diagnosis were influenced by genetic and nonshared environmental factors (h2=.30-.45). The genetic correlations between rumination and depression were moderate to large (rA=.40-.82), suggesting that a substantial proportion of the genetic influences on rumination overlap with those on depression. Results were similar when examining self-reported depressive symptoms and interview-based diagnosis of major depressive disorder. These results highlight the importance of rumination in the integration of cognitive and genetic models of depression risk.