SEASONAL-VARIATIONS IN-HOSPITAL ADMISSIONS FOR AFFECTIVE-DISORDERS BYGENDER AND ETHNICITY

Hospital admission statistics for depression and mania have shown sign ificant seasonal patterns. The present investigation was conducted to establish the pervasiveness of the impact of seasons on mood disorder presentation at Birmingham (52 degrees North) by gender and ethnicity. Non-mood disorder admissions were examined as a control to determine the specificity of any seasonal variation to affective illness. Case n otes for 992 admissions, during January-December 1995 inclusive, to an inpatient unit were reviewed retrospectively. Admission data were bro ken down by fender and into three ethnic groups: Asian, white and blac k. Seasonality in admissions for depression, bipolar disorder and non- mood disorders was tested by gender and ethnicity. Admission frequenci es for depression showed significant seasonal pattern, with the incide nce of depression being highest in winter. Total admissions, bipolar a nd non-mood disorders did not show any significant seasonal variabilit y. A gender effect was evident on seasonality of admissions for affect ive illness, with significant winter peak for depression and summer pe ak for bipolar disorder in women only. The Asian group was the only et hnic group that showed significant seasonal variation in depression, w ith a greater number of depressive episodes in winter. Environmental v ariables were related significantly to the incidence of mood disorders . Specific seasonal effect for affective illness was evidenced by the non-existence of seasonality in other psychiatric disorders. The rever se seasonal pattern for depression and mania suggests a maladaptive re sponse of vulnerable individuals to specific functions of seasons.