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 .
Treatment of winter depression in Norway
Thirty‐four patients with seasonal affective disorder , winter depression type ( WD ) were r and omly distributed to receive the selective monoamine oxidase‐A inhibitor moclobemide ( 400 mg daily ) or placebo in a double‐blind , parallel group study lasting for up to 14 weeks . Severity measures were the Montgomery‐Åsberg Depression Rating Scale ( MADRS ) extended with characteristic symptoms of WD ; summed score of the “ atypical ” symptoms hypersomnia , hyperphagia and carbohydrate craving ; and Clinical Global Impressions ( CGI ) . After 3 weeks , patients with unsatisfactory response were switched to open moclobemide . Three patients on placebo dropped out before 3 weeks . Extended MADRS and CGI showed no significant difference between the groups at 3 weeks , whereas the atypical score was reduced significantly more on moclobemide than on placebo already after one week . Nonresponders after 3 weeks ( 9 of 16 on moclobemide and 7 of 15 on placebo ) improved rapidly after being given open moclobemide . Predictor analysis showed a remarkably high negative correlation between improvement at 3 weeks ( extended MADRS ) and age in the placebo group and a strong , nonsignificant trend in the same direction in the moclobemide group . Dichotomizing the patients according to the median age ( 45 years ) result ed in a somewhat better effect  of moclobemide than placebo in the older age group . There were no significant differences in side effects between moclobemide and placebo
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 .