Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL.

Background: Seasonal affective disorder (SAD) can cause significant distress and impairment. No antidepressant studies have previously attempted to prevent the onset of autumn-winter depression.

Methods: Three prospective, randomized, placebo-controlled prevention trials were conducted on 1042 SAD patients, enrolled in autumn and treated while still well, across the northern US and Canada. Patients received either bupropion XL 150-300 mg or placebo daily by mouth from enrollment until spring and were then followed off medications for 8 additional weeks. Primary efficacy variables were end-of-treatment depression-free rates and survival distributions of depressive recurrence.

Results: Despite a reported average of 13 previous seasonal depressive episodes, almost 60% of patients had never previously been treated for depression. Major depression recurrence rates during the three studies for bupropion XL and placebo groups were 19% versus 30% (p = 0.026), 13% versus 21% (p = 0.049), and 16% versus 31%; yielding a relative risk reduction across the three studies of 44% for patients taking bupropion XL. Survival analyses for depression onset also favored bupropion XL over placebo (p = .081, .057, and <.001).

Conclusions: It is possible to prevent recurrence of seasonal major depressive episodes by beginning bupropion treatment early in the season while patients are still well.