Cognitive-behavioral therapy, light therapy, and their combination in treating seasonal affective disorder

The need to develop supplementary or alternative treatments for seasonal affective disorder (SAD) is underscored by the significant minority (47%) of SAD patients that is refractory to light therapy, the persistence of residual symptoms despite light treatment, and poor long-term compliance with light use. Because preliminary studies suggest that cognitive and behavioral factors are involved in SAD, cognitive-behavioral therapy (CBT) warrants investigation as a possible treatment option.

We piloted a 6-week randomized clinical trial to compare a standard light therapy protocol; a novel, SAD-tailored, group CBT intervention; and their combination in ameliorating and remitting a current SAD episode and as prophylaxis against episode recurrence. Depressive symptom severity and remission rates were assessed at post-treatment and at a 1-year follow-up visit to examine long-term treatment durability.

CBT, light therapy, and their combination all demonstrated significant reductions in depressive symptoms on two different outcome measures. Remission rates varied by measure, but did not reach statistical significance. During the subsequent winter, CBT, particularly in combination with light therapy, appeared to improve long-term outcome regarding symptom severity, remission rates, and relapse rates. No CBT-treated participant, with or without light, experienced a full SAD relapse compared to over 60% of those treated with light alone.

These results should be viewed as preliminary and are limited by the small sample size (n=23) and lack of a control group.

The nearly half of SAD patients who do not remit with light alone may benefit from CBT as an adjunct or alternative treatment, especially as a prophylaxis against episode recurrence.