Cognitive-behavioral factors in seasonal affective disorder.

To longitudinally examine cognitive-behavioral correlates of seasonal affective disorder (SAD), the authors assessed women with a history of SAD and nondepressed, matched controls across fall, winter, and summer. SAD history participants reported more automatic negative thoughts throughout the year than controls and demonstrated a progression from decreased activity enjoyment during fall to reduced activity frequency during winter. Ruminative response style, measured in fall, predicted symptom severity during the winter. Across assessments, SAD history women endorsed greater depressive affect in response to low light intensity stimuli than to bright or ambiguous intensity stimuli, but less depressed mood to bright light stimuli than controls. These results suggest that the cognitive-behavioral factors related to nonseasonal depression may play a role in SAD.