Clinical Question: Is light therapy an acceptable alternative to antidepressants for patients with seasonal affective disorder (SAD)?

Setting: Outpatient (specialty)

Study Design: Randomized controlled trial (double-blinded)

Allocation: Concealed

Synopsis: Light therapy and antidepressants are effective in the treatment of SAD, but few studies have directly compared the two treatments. The investigators identified 96 adults (mean age = 42 years) meeting Diagnostic and Statistical Manual of Mental Disorders, 4th ed. criteria for major depressive disorder with a seasonal (winter) pattern with scores greater than 23 on the 24-item Hamilton depression scale (HAMD). Participants were randomized in double-blind fashion (concealed allocation) to eight weeks of 10,000-lux light treatment plus placebo or 100-lux light treatment (placebo light) plus fluoxetine (Prozac) 20 mg per day. Light treatment occurred for 30 minutes as soon as possible after awakening, between 7:00 a.m. and 8:00 a.m. Individuals blinded to treatment group assignment assessed outcomes using the HAMD. A significant clinical response included a 50 percent or greater reduction from baseline in HAMD score. Follow-up occurred for 96 percent of participants for eight weeks.

Using intention-to-treat analysis, there were no significant differences between the light and fluoxetine treatment groups in clinical response rates (67 percent for both treatments) or remission rates (50 versus 54 percent, respectively). There also were no significant differences in either outcome noted between the two treatment groups for a subset of patients with severe depression. The placebo light, although dim, may have some clinical effect, possibly by accentuating the benefit of fluoxetine. More fluoxetine-treated patients complained of agitation, sleep disturbance, and palpitations. However, treatment-emergent adverse event rates and drop-out rates were similar in both groups.

Bottom Line: Light therapy and fluoxetine are equally effective treatment options for patients with SAD. Patient preference and an individual assessment of risks and benefits should guide treatment selection. (Level of Evidence: 1b)