Prospectively assessed summer mood status in major depression, recurrent with seasonal pattern: Evidence for SAD's construct validity.

OBJECTIVE: Seasonal patterns are often undetectable in population-based depression studies, calling into question the existence of winter seasonal affective disorder (SAD). If SAD has construct validity, individuals with SAD should show spontaneous depression remission in the summer. Data are sparse on prospectively assessed summer mood status in confirmed SAD patients. METHOD: We conducted prospective summer followup of community adults who, the winter before, were diagnosed with Major Depression, Recurrent with Seasonal Pattern on the Structured Clinical Interview for DSM-IV Axis I Disorders, developed a current SAD episode on the Structured Interview Guide for the Hamilton Rating Scale for Depression-Seasonal Affective Disorder Version (SIGH-SAD), and enrolled in a clinical trial comparing group cognitive-behavioral therapy for SAD and light therapy. In July/August after treatment, 143/153 (93.5 %) participants provided data on the SIGH-SAD, the Beck Depression Inventory-Second Edition, and the Longitudinal Interval Followup Evaluation (LIFE). RESULTS: Summer mean depression scores were in the normal range, with the substantial majority in remission across different measures. On the LIFE, 113/143 (79.0 %) experienced complete summer remission, 19/143 (13.3 %) experienced partial summer remission, and 11/143 (7.7 %) had major depression in the summer. Depression scores were significantly lower at summer than post-treatment in both treatments, indicating incomplete treatment response. LIMITATIONS: This was a single-site study with a relatively homogeneous sample. CONCLUSIONS: Supporting construct validity for SAD, the substantial majority experienced complete summer remission, with a minority in partial remission and a very small minority in episode. Both treatments left residual symptoms at treatment endpoint compared to summer.

Cognitive Vulnerabilities as Prognostic Predictors of Acute and Follow-up Outcomes in Seasonal Affective Disorder Treatment with Light Therapy or Cognitive-Behavioral Therapy.

BACKGROUND: First-line treatments for winter seasonal affective disorder include light therapy and cognitive-behavioral therapy; however, it is unclear whether particular patient profiles respond differentially to each treatment type. This study examined baseline patient cognitive and chronobiological vulnerabilities as prognostic and prescriptive predictors of acute and follow-up treatment outcomes. METHODS: 177 adults with seasonal affective disorder were randomized to 6-weeks of either light therapy or cognitive-behavioral therapy. Participants completed baseline measures of cognitive vulnerabilities (Dysfunctional Attitudes Scale; Ruminative Response Scale; Seasonal Belief Questionnaire) and chronobiological vulnerability (Morningness-Eveningness Questionnaire). Depression was assessed at pre- and post-treatment and at follow-ups one and two winters later. RESULTS: Pre-treatment depression severity correlated significantly with each cognitive vulnerability measure, and significantly predicted future depression. After controlling for pre-treatment depression, higher scores on the Morningness-Eveningness Questionnaire were prognostic of lower depression at treatment endpoint, but no cognitive vulnerability emerged as a prognostic or prescriptive predictor of outcome. CONCLUSIONS: Greater morningness was associated with less severe post-treatment depression in both cognitive-behavior therapy and light therapy. No cognitive vulnerability emerged as a prognostic or prescriptive predictor, perhaps because they correlated with pre-treatment depression severity, a robust predictor of outcome. Future research should test alternative cognitive constructs.