Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .
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 prospect i ve , r and omized , 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
Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .