Short winter days can trigger seasonal affective disorder. Vermont researchers said they got longer lasting therapeutic results with cognitive behavioral therapy than with light therapy--apparently because people tire of using the lights.
Short winter days trigger depression in people susceptible to seasonal affective disorder (SAD). Light therapy has been shown to treat it successfully, but a research team in Vermont found that talk therapy worked even better. That is important because patients tend to use light therapy initially, and find it helps get them through the winter. But they tend to discontinue it the next time winter rolls around and their depression is likely to return. Talk therapy had a more lasting effect.
Kelly Rohan, PhD and colleagues at the University of Vermont in Burlington, VT followed 177 adults treated for depression. The subjects were randomized to get either cognitive behavioral therapy (CBT) or light therapy. That treatment focuses on getting patients to avoid doing things that add to their depressed state--like staying inside and avoiding social activities.
Their depression was measured by using standard tests including the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version.
On followup a year after the therapy there was no difference in the recurrence rates in the two groups of patients.
But when the patients were assessed two years later, the researchers found a smaller group of patients had recurrences of their depression if they got CBT (27.3%) than did those who had light therapy (45.6%).
"CBT-SAD wassuperior to light therapy two winters following acute treatment, suggesting greater durability for CBT-SAD," the researchers wrote in the American Journal of Psychiatry.
The study was done at the university's "mood and seasonality" laboratory.
The patients who got light therapy used a device called SunRay, whcih emits cool-white fluorescent light through an ultraviolet filer, and they sat in front of it for 30 minutes after awakening.
The protocol called for patients to continue to use the lights "until their typical time of spontaneous remission" and to return the light boxes in May.
Over 14 million Americans suffer from SAD, ranging from 1.5 percent of the population in southern states like Florida to over 9 percent in the northern regions of the country. An estimated 10 to 20 percent of all cases of recurrent depression follow a seasonal pattern.
The study was funded by a $2 million grant from the National Institute of Mental Health.