Study of family history in seasonal affective disorder

In our investigation we assessed the risk of morbidity for psychiatric disorders among the first-degree relatives of patients with seasonal affective disorders (SAD) and compared it with a control group of patients suffering from nonseasonal mood disorders (NSMD).

Over a period of 12 months (June 1994 to May 1995) we recruited patients consecutively admitted to our psychiatric university outpatient clinic in a prospective study. All patients were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, revised 4th edition. A total of 344 patients presented themselves with a diagnosis of affective disorder. Out of these, 36 were diagnosed as having SAD. From the same group of 344 patients, we selected a matched control group of 36 patients suffering from NSMD. The experimental and control groups were matched according to sex, age, severity of illness and number of siblings.

There was no significant difference concerning the lifetime prevalences for psychiatric disorders among the fist-degree relatives in both groups (SAD = 16.5% and NSMD = 19%).

It seems that there is no difference in familiarity for psychiatric disorders between SAD and NSMD.