The Can-SAD Study: A Randomized Controlled Trial of the Effectiveness of Light Therapy and Fluoxetine in Patients With Winter Seasonal Affective Disorder

Raymond W. Lam, M.D., F.R.C.P.C., Anthony J. Levitt, M.B.B.S., F.R.C.P.C., Robert D. Levitan, M.D., F.R.C.P.C., Murray W. Enns, M.D., F.R.C.P.C., Rachel Morehouse, M.D., F.R.C.P.C., Erin E. Michalak, Ph.D. and Edwin M. Tam, M.D.C.M., F.R.C.P.C. American Journal of Psychiatry , May 1, 2006

Abstract

OBJECTIVE: Light therapy and antidepressants have shown comparableefficacy in separate studies of seasonal affective disordertreatment, but few studies have directly compared the two treatments.This study compared the effectiveness of light therapy and anantidepressant within a single trial. METHOD: This double-blind,randomized, controlled trial was conducted in four Canadiancenters over three winter seasons. Patients met DSM–IVcriteria for major depressive disorder with a seasonal (winter)pattern and had scores 23 on the 24-item Hamilton DepressionRating Scale. After a baseline observation week, eligible patientswere randomly assigned to 8 weeks of double-blind treatmentwith either 1) 10,000-lux light treatment and a placebo capsule,or 2) 100-lux light treatment (placebo light) and fluoxetine,20 mg/day. Light treatment was applied for 30 minutes/day inthe morning with a fluorescent white-light box; placebo lightboxes used neutral density filters. RESULTS: A total of 96 patientswere randomly assigned to a treatment condition. Intent-to-treatanalysis showed overall improvement with time, with no differencesbetween treatments. There were also no differences between thelight and fluoxetine treatment groups in clinical response rates(67% for each group) or remission rates (50% and 54%, respectively).Post hoc testing found that light-treated patients had greaterimprovement at 1 week but not at other time points. Fluoxetinewas associated with greater treatment-emergent adverse events(agitation, sleep disturbance, palpitations), but both treatmentswere generally well-tolerated with no differences in overallnumber of adverse effects. CONCLUSIONS: Light treatment showedearlier response onset and lower rate of some adverse eventsrelative to fluoxetine, but there were no other significantdifferences in outcome between light therapy and antidepressantmedication. Although limited by lack of a double-placebo condition,this study supports the effectiveness and tolerability of bothtreatments for seasonal affective disorder and suggests thatother clinical factors, including patient preference, shouldguide selection of first-line treatment.

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