Seasonal Affective Disorder

Excerpt

Seasonal affective disorder (SAD) is a mood disorder subtype characterized by recurrent depressive episodes with a seasonal pattern. It typically presents with major depressive episodes starting in late autumn or winter and remitting by spring or summer. Conceptualized by Rosenthal et al in 1984, SAD symptoms include atypical features such as hypersomnia, overeating, carbohydrate craving, and significant fatigue, in addition to typical depressive symptoms. Despite its distinct seasonal pattern, it is not classified separately in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) but as a specifier for major depressive disorder and bipolar disorder. There is an ongoing debate about its classification within DSM-5 TR, highlighting the need for continuing vigorous research.

Understanding SAD's symptomatology and biological basis is critical for developing effective treatments as it causes significant psychiatric morbidity. Research shows its prevalence varies globally, higher in regions farther from the equator, highlighting daylight exposure's role in the disorder's onset. Prevalence rates range from 1% to 10%, influenced by latitude and assessment methods, with variations observed between countries such as the US and Australia. The etiology of SAD involves complex factors like circadian rhythm disruptions, changes in melatonin and serotonin levels, and photoperiod sensitivity. These factors underscore the need for further investigation into SAD's biological and neurological underpinnings.