Cognitive-behavioral Therapy vs. Light Therapy for Preventing SAD Recurrence

Study Summary

Major depression is a highly prevalent, chronic, and debilitating mental health problem with significant social cost that poses a tremendous economic burden. Winter seasonal affective disorder (SAD) is a subtype of recurrent major depression involving substantial depressive symptoms that adversely affect the family and workplace for about 5 months of each year during most years, beginning in young adulthood. This clinical trial is relevant to this public health challenge in seeking to develop and test a time-limited (i.e., acute treatment completed in a discrete period vs. daily treatment every fall/winter indefinitely), palatable cognitive-behavioral treatment with effects that endure beyond the cessation of acute treatment to prevent the annual recurrence of depression in SAD. Aim (1) To compare the long-term efficacy of cognitive-behavioral therapy (CBT) and light therapy on depression recurrence status, symptom severity, and remission status during the next winter season (i.e., the next wholly new winter season after the initial winter of treatment completion), which we argue to be the most important time point for evaluating clinical outcomes following SAD intervention. Hypothesis: CBT will be associated with a smaller proportion of depression recurrences, less severe symptoms, and a higher proportion of remissions than light therapy in the next winter. The study is designed to detect a clinically important difference between CBT and light therapy in depressive episode recurrences during the next winter, the primary endpoint, in an intent-to-treat analysis. Aim (2) To compare the efficacy of CBT and light therapy on symptom severity and remission status at post-treatment (treatment endpoint). Hypothesis: CBT and light therapy will not differ significantly on post-treatment outcomes.

Primary Outcome

The SIGH-SAD (Williams et al., 1992), the most commonly used clinical assessment device for detecting changes in SAD symptoms in light therapy research, includes the 21-item Structured Interview Guide for the Hamilton Rating Scale for Depression (HAM-D) and a supplementary 8-item subscale to assess atypical depressive symptoms associated with SAD. The primary outcome measure is SIGH-SAD recurrence status at the next winter followup. A trained rater, blind to the treatment condition, will adminis

Interventions

• BEHAVIORAL Cognitive-Behavioral Therapy (CBT)
• DEVICE Light Therapy (LT)