Category: Adult Depression / Dysthymia

PS3- #B44 - Patterns of Individual Symptom Remission Across Treatment With Light Therapy or CBT for SAD

Friday, Nov 17
11:00 AM – 12:00 PM
Location: Indigo Ballroom CDGH, Level 2, Indigo Level

Keywords: Adult Depression | Treatment-CBT | Treatment-Other

We completed a randomized clinical trial comparing two theoretically distinct treatments for seasonal affective disorder (SAD): cognitive-behavioral therapy (CBT-SAD), which is designed to engage a cognitive vulnerability target, and light therapy (LT), which is designed to engage a chronobiological target. CBT-SAD and LT were comparably efficacious acute treatments (post-treatment remission rates = 47.6% in CBT-SAD and 47.2% in LT; Rohan et al., 2015).  Here, we explore the course of individual depressive symptom offset and whether these symptoms differ in their time to remission across CBT-SAD vs. LT to inform differential mechanisms related to remission.


A sample of 177 community adults in a current episode of Major Depression, Recurrent with Seasonal Pattern were randomized to 6-weeks of CBT-SAD (n=88; twice-weekly 90-minute group sessions) or LT (n=89; 10,000-lux initiated at 30-min./day upon waking and subsequently adjusted per an algorithm). Depressive symptoms were assessed via items on the 29-item Structured Interview Guide for the Hamilton Rating Scale for Depression-SAD Version (SIGH-SAD) at pre-treatment and weekly during treatment. These secondary analyses included the 17 SIGH-SAD items endorsed by 40 or more participants at pre-treatment. Within each of the 17 included symptoms, participants with fewer than 3 weeks of missing data and who endorsed the symptom at baseline were included.


For each symptom, survival analyses were used to assess time to sustained remission, defined as week the item score became zero and remained zero through treatment endpoint. For most (13/17) symptoms, CBT-SAD and LT did not differ in time to remission. However, for four symptoms (early insomnia, psychic anxiety, hypersomnia, and social withdrawal), LT led to symptom remission more quickly than CBT-SAD. The observation that LT leads to faster remission of early insomnia and hypersomnia is consistent with the theory that SAD is related to a pathological circadian phase-shift that can be corrected with LT. Faster remission of social withdrawal and psychic anxiety in LT was unexpected. It is possible that the time in treatment associated with CBT-SAD (i.e., twice-weekly sessions in the evenings) limited social activities more so than LT. The psychic anxiety item predicted LT response in one prior study but not in another (MacKenzie & Levitan, 2005; Terman, Amira, Terman, & Ross, 1996). Our findings suggest that LT may engage the biological underpinnings of psychic anxiety more quickly than CBT-SAD. These results provide insight into mechanisms underlying overall remission, and highlight ways to maximally engage treatment targets and increase the effectiveness of current and future interventions.

Jonah Meyerhoff

Graduate Student
University of Vermont
Burlington

Michael Young

Professor of Psychology
Illinois Institute of Technology
Chicago, Illinois

Kelly J. Rohan

Professor of Psychology
University of Vermont
Burlington, Vermont

Julia Camuso

Graduate Student
University of Vermont
Burlington, Vermont