Light therapy is a proven approach to treat acute SAD, but previous studies show that most patients fail to reinitiate light therapy in subsequent winters—leaving them vulnerable to the recurrence of depression. A recent analysis found CBT-SAD to be as effective as light therapy in alleviating depression associated with SAD, but it was unknown how long lasting these effects might be.
In the current study, researchers examined outcomes for 177 participants with SAD who were randomly assigned to receive CBT-SAD (two 90-minute sessions a week) or light therapy (30 minutes each morning) for six weeks. The participants were then assessed one and two winters later. The primary outcome was winter depression recurrence status on the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version.
In the first follow-up winter, recurrence of SAD was the same in the two groups (28.9% for CBT and 24.9% for light therapy). At the second winter, CBT-SAD had a 27.3% recurrence rate compared with 45.6% for light therapy. Participants treated with CBT-SAD also reported less severe symptoms and showed a higher rate of remission, as measured by the Beck Depression Inventory-Second Edition scores.
“Light therapy remains an important treatment for SAD, but this study shows the value of educating people about their illness and behaviors that can help manage it,” said Norman Rosenthal, M.D., a clinical professor of psychiatry at Georgetown University School of Medicine. Rosenthal, an expert on SAD, was not involved in the study.
For more on the effectiveness of CBT and light therapy for SAD, see the Psychiatric News article “CBT, Light Therapy Found Comparable for Seasonal Affective Disorder.”
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