Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder

Abstract

Objective: The central public health challenge for winter seasonal affective disorder (SAD) is recurrence prevention. Preliminary studies suggest better long-term outcomes following cognitive-behavioral therapy tailored for SAD (CBT-SAD) than light therapy. The present study is a large, randomized head-to-head comparison of these treatments on outcomes one and two winters after acute treatment.

Method: Community adults with major depression, recurrent with seasonal pattern (N=177) were followed one and two winters after a randomized trial of 6 weeks of CBT-SAD (N=88) or light therapy (N=89). Prospective follow-up visits occurred in January or February of each year, and major depression status was assessed by telephone in October and December of the first year. The primary outcome was winter depression recurrence status on the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version (SIGH-SAD). Other outcomes were depression severity on the SIGH-SAD and the Beck Depression Inventory-Second Edition (BDI-II), remission status based on severity cutoff scores, and major depression status from tracking calls.

Results: The treatments did not differ on any outcome during the first year of follow-up. At the second winter, CBT-SAD was associated with a smaller proportion of SIGH-SAD recurrences (27.3% compared with 45.6%), less severe symptoms on both measures, and a larger proportion of remissions defined as a BDI-II score ≤8 (68.3% compared with 44.5%) compared with light therapy. Nonrecurrence at the next winter was more highly associated with nonrecurrence at the second winter among CBT-SAD participants (relative risk=5.12) compared with light therapy participants (relative risk=1.92).

Conclusions: CBT-SAD was superior to light therapy two winters following acute treatment, suggesting greater durability for CBT-SAD.

Trial registration: ClinicalTrials.gov NCT01714050.

Figure 1

Note: The October and December tracking phone call procedures were in place for all but the first cohort of 24 participants that was recruited in the initial fall/winter of study (2006-2007).

Figure 2. Recurrence Rates and Depression Severity at Next and Second Winter Followup in Cognitive-Behavioral Therapy and Light Therapy

Note: See Table 1 for measure abbreviations. These data were derived from the primary analysis, an intent-to-treat analysis based on multiple imputation of missing followup depression scores.