Lack of differential symptom change with cognitive-behavioral vs. light therapy for winter depression: A network intervention analysis.

Background: This study is a network intervention analysis comparing the symptomatic response of two first-line treatments for winter seasonal affective disorder (SAD): light therapy (LT) and group cognitive-behavioral therapy for SAD (CBT-SAD). Methods: Scores on the Beck Depression Inventory-II at mid- and post-treatment on individual items and on four previously-identified symptom clusters were examined in SAD patients randomly assigned to receive LT (n = 88) or CBT-SAD (n = 75). Results: No treatment differences in either individual symptoms or symptom cluster scores were observed. In both mid- and post-treatment networks, symptoms were primarily associated with each other within their respective, cognitive, vegetative, and affective domains (regardless of treatment). For clusters, Loss of Vitality, Dysregulation, and Negative Cognition were associated with each other (regardless of treatment). At post-treatment only, Increased Appetite and Weight was (relatively weakly) associated with Loss of Vitality. Conclusions: The lack of treatment differences indicates that these two mechanistically different treatments do not differ in effect on symptoms or symptom clusters. Future work should examine the association of treatment with symptom types over shorter time intervals.