CBT Equal to Light Therapy for SAD

Miriam Davis, PhD

May 11, 2015

Cognitive-behavioral therapy (CBT) modified to treat seasonal affective disorder (SAD) is as effective as light therapy, new research suggests.

Results of a 6-week randomized, controlled clinical trial showed that CBT for SAD (CBT-SAD) performed as well as light therapy for a current episode of major depression that was recurrent with a seasonal pattern.

"This study was undertaken to explore alternatives to light therapy, which is the current standard of care for SAD. It found that CBT-SAD adds a plausible alternative," lead investigator Kelly Rohan, PhD, professor of psychological science, University of Vermont, in Burlington, told Medscape Medical News.

The study was published online April 10 in the American Journal of Psychiatry.

Need for Better Treatments

Introduced in the 1980s, light therapy involves sitting in front of a light box that emits 10,000 lux for about 30 minutes each morning from fall to spring.

"Five months of daily treatment during the winter months is not for everybody...and meta-analyses show that remission is around 53%, which means that patients have a 50/50 chance of remitting," said Dr Rohan.

CBT-SAD is a modification of CBT for depression. "It consists of cognitive restructuring, which seeks to identify negative thoughts and replace them with less negative thoughts, and behavioral activation, which seeks to identify activities that are engaging and pleasurable, whether indoors or outdoors, to improve coping with winter," she added.

In the study, 177 adults were randomly assigned to daily light therapy or to CBT-SAD for two 90-minute group therapy sessions per week for 6 weeks.

The study's outcome measures were improvements on the self-reported Beck Depression Inventory (BDI) and the clinician-administered Structured Interview Guide for the Hamilton Rating Scale for Depression–SAD Version (SIGH-SAD).

The SIGH-SAD adds eight items to the traditional 21 items of the Hamilton Rating Scale to capture symptoms more common to SAD, including oversleeping, overeating, and weight gain.

With these measures, "both treatments showed large and comparable benefits for SAD," said Dr Rohan. Using the SIGH-SAD, remission of depression symptoms occurred in 47.6% of the CBT-SAD group and 47.2% of the light therapy group. Using the BDI, remission occurred in 56.0% of the CBT group and 63.6% of the light therapy group.

"The patients in remission had scores that look more like nondepressed individuals. There was a full lifting of depression in a clinically meaningful way," she said.

One of the unique features of the study was that it included SAD patients with comorbidities who were receiving stable doses of antidepressant medication.

"The pendulum has swung in clinical trials to include people who look more like real SAD patients. The trial was designed to embrace heterogeneity and model a real-world sample," said Dr Rohan.

CBT and light therapy showed the same benefits, regardless of whether the patients had comorbidity (most typically, an anxiety disorder) or were taking antidepressant medication.

"CBT-SAD should be disseminated into practice and considered as a viable alternative to light therapy in treatment decision making," write the authors. The next step is to analyze the clinical trial data for the 2 years posttreatment to determine whether the effects of CBT-SAD are durable.

Adjunctive, Not Alternative

Commenting on the study findings for Medscape Medical News, Michael Terman, PhD, president of the Center for Environmental Therapeutics and professor, Department of Psychiatry, Columbia University, in New York City, said that CBT for SAD is a "useful adjunct to light therapy" but not an alternative because it does not bring the body's "internal clock into synchrony with society's obligatory pattern of sleeping and waking."

He added that a problem with the study is that "the present authors did not instruct patients to wake up for light therapy at the optimum circadian time," which is 7.5 to 9 hours after melatonin onset during the prior evening. Had they done so, "light therapy might well have been found superior to CBT-SAD," he said.

The research was funded by the National Institute of Mental Health. Dr Rohan has received book royalties from Oxford University Press for her treatment manual for CBT-SAD. Dr Terman reports that the Center for Environmental Therapeutics, a nonprofit organization for which he is president, receives funds from a light box supplier.

Am J Psychiatry. Published online April 10, 2015. Abstract

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