FAMILY STUDY OF EARLY-ONSET DYSTHYMIA - MOOD AND PERSONALITY-DISORDERS IN RELATIVES OF OUTPATIENTS WITH DYSTHYMIA AND EPISODIC MAJOR DEPRESSION AND NORMAL CONTROLS

Background: The nosological status of dysthymia has generated consider able controversy. The major issues include whether dysthymia should be classified as a form of mood or personality disorder and, if dysthymi a is classified as a mood disorder, whether it is sufficiently distinc t from major depression to warrant a separate category. Methods: We co nducted a family study of 97 outpatients with early-onset dysthymia, 4 5 outpatients with episodic major depression, and 45 normal controls, and their 882 first-degree relatives. Axis I and II disorders were ass essed in relatives using direct and informant interviews and all avail able medical records. Results: The rate of major depression in the rel atives of early-onset dysthymic probands was significantly greater tha n in the relatives of normal controls and nonsignificantly greater tha n in the relatives of episodic major depressive probands. The rate of dysthymia was significantly greater in the relatives of dysthymic prob ands than in relatives of both major depressive probands and normal co ntrols. Rates of most personality disorders were increased in the rela tives of the dysthymic and major depressive probands compared with rel atives of normal controls. In addition, the relatives of dysthymic pro bands had significantly higher rates of and personality disorder and a ny cluster B disorder than those of episodic major depressive probands , although these differences disappeared after controlling for Axis II comorbidity in the probands. Finally, dysthymic probands with and wit hout a lifetime history of major depression did not differ on rates of psychiatric disorders in relatives. Conclusions: There is a strong fa milial relationship between dysthymia and major depression. However, d ysthymia is also somewhat distinct in that it aggregates specifically in the families of patients with dysthymia. Finally, dysthymia and epi sodic major depression both appear to have a familial association with the personality disorders, although the link appears to be somewhat s tronger for dysthymia.