Affective disorders and multiple sclerosis: a controlled study on 65 Italian patients.

A high prevalence of major mood disorders in multiple sclerosis (MS) patients has been reported. In this study, we investigated the frequency of previous or present major mood disorders in 65 patients with clinically definite multiple sclerosis (Poser criteria) and in 31 polyneuropathy (PNP) patients. All patients underwent a questionnaire designed after DSM-IV definitions for major mood disorders. A higher lifetime risk for development of a major mood disorder was evident in MS patients (log rank test, p<0.001). Of all MS patients with a major mood disorder, at least 34% had one first-degree relative affected by a mood disorder, while the corresponding figure was 14% among PNP cases. Our data confirm the high lifetime risk for depression in MS patients and suggest that, at least in a subset of MS patients with depression, the genetic basis for depression operates with similar mechanisms as those at work in families with primary depression. However, this is not necessarily true for other subsets of depressed MS patients' families.