Increased risk for recurrent major depression in DYT1 dystonia mutation carriers.

BACKGROUND Prior studies suggest that dystonia is comorbid with affective disorders. This comorbidity could be a reaction to a chronic debilitating disorder or expression of a predisposing gene. The authors took advantage of the identification of a gene for dystonia, DYT1, to test these alternative explanations. METHODS The authors administered a standardized psychiatric interview to members of families with an identified DYT1 mutation. The authors classified family members into three groups: mutation carriers with dystonia (manifesting carriers; n = 96), mutation carriers without dystonia (non-manifesting carriers; n = 60), and noncarriers (n = 65). RESULTS The risk for recurrent major depressive disorder was increased in both non-manifesting carriers (RR = 4.95, CI = 1.72 to 14.29) and manifesting carriers (RR = 3.62, CI = 1.00 to 10.53) compared with noncarriers. Mutation carriers also had earlier age at onset of recurrent major depressive disorder than noncarriers. The severity of motor signs was not associated with the likelihood of recurrent depression. Mutation carriers did not have an increased risk for other affective disorders, such as single major depression or bipolar disorder. CONCLUSIONS Early-onset recurrent major depression is associated with the DYT1 GAG mutation and this association is independent of motor manifestations of dystonia. These findings suggest that early-onset recurrent depression is a clinical expression of the DYT1 gene mutation.