Seasonal Affective Disorder: An update

Abstract

Seasonal Affective Disorder (SAD) is a condition of regularly recurring depression in fall or winter, with a remission the following spring or summer. The cognitive and emotional symptoms are similar to other types of depression but the vegetative symptoms are the reverse of classic depressive vegetative symptoms, namely increased sleep and increased appetite. SAD is a common condition, but the exact prevalence rates vary between different studies and countries, however, it is consistently found to be more common in women and in young adults. SAD probably occurs in children although not as commonly as in adults. Some studies have found that certain ethnic groups who live at high northern latitudes may have adapted to the long arctic winter.

The pathophysiology of SAD seems to be heterogeneous as research on circadian rhythms, neurotransmitter function and genetic hypotheses have shown discrepant results.  Systematic reviews 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. Clinical studies show equal effectiveness with light and antidepressants. Dawn stimulation, negative air ions, exercise and cognitive behaviour therapy are under investigation.