Seasonal concordance of recurrence in mood disorder patients.

The aim of the present study is to evaluate the seasonal pattern of recurrences and the concordance among first episode (index episode) versus the subsequent recurrences in a sample of 210 patients affected by mood disorders, referred to the Mood Disorder Unit of San Raffaele Hospital. The most depressive recurrences are in spring for unipolar subjects and in fall for bipolars. Manic episodes are more frequent in summer. Patients presented a high concordance rate between the first and the second episode, female patients were more concordant than male subjects, and patients with low cycle of illness (one episode every six or more years) were the most concordant ones.