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 .
Effects of Alpha-Methyl-Para-Tyrosine-Induced Catecholamine Depletion in Patients with Seasonal Affective Disorder in Summer Remission
Noradrenergic and dopaminergic mechanisms have been proposed for the pathophysiology of seasonal affective disorder ( SAD ) . We investigated the effects of catecholamine depletion using α-methyl-para-tyrosine ( AMPT ) , an inhibitor of tyrosine hydroxylase , in patients with SAD in natural summer remission . Nine drug-free patients with SAD by DSM-IV criteria , in summer remission for at least eight weeks , completed a double-blind , crossover study . Behavioral ratings and serum HVA and MHPG levels were obtained for 3-day sessions during which patients took AMPT or an active control drug , diphenhydramine . The active AMPT session significantly reduced serum levels of HVA and MHPG compared with the control diphenhydramine session . The AMPT session result ed in higher depression ratings with all nine patients having significant clinical relapse , compared with two patients during the diphenhydramine session . All patients returned to baseline scores after drug discontinuation . Catecholamine depletion results in significant clinical relapse in patients with SAD in the untreated , summer-remitted state . AMPT-induced  depressive relapse may be a trait marker for SAD , and /or brain catecholamines may play a direct role in the pathogenesis of SAD
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 .