An overview of seasonal affective disorder and its treatment options

Seasonal affective disorder (SAD) is defined as a history of major depressive episodes that recur regularly at a particular time of year. Depending on the diagnostic instruments and criteria available, the reported prevalence (1%-10%) varies. Neurotransmitter abnormalities have been implicated in the pathophysiology, but they do not necessarily explain the seasonal pattern or the known chronobiological abnormalities in SAD compared with nonseasonal depression. Circadian rhythm abnormalies have been hypothesized to account for these aspects of SAD, and they provide a rationale for the therapeutic use of light therapy. Family history, twin, and molecular genetics studies suggest that hereditary factors are also involved. Light therapy and antidepressant medication are effective treatment options, with limited evidence for the efficacy of psychotherapy. Some studies demonstrate that narrow-band short wavelength "blue" light, naturalistic dawn simulation, and high-density negative air ionization are effective. Patients should be informed of the benefits of diet and exercise. Light therapy should be clinically monitored in the same manner, as it is done for other antidepressant treatments.