Seasonal affective disorder Health Article

Definition

Seasonal affective disorder, often abbreviated as SAD, is a type of mood disorder that follows an annual pattern consistent with the seasons. The most common course for SAD includes an onset of depressive symptoms late in the fall, continuation of symptoms throughout winter, and remission of symptoms in the spring.

Description

According to the handbook used by mental health professionals to diagnose mental disorders, the Diagnostic and Statistical Manual of Mental Disorders fourth edition text revised, or DSM-IV-TR, SAD is not considered a disorder or syndrome on its own. Instead, SAD is considered a pattern specifier, or subtype, of another mood disorder diagnosis. For example, an individual may be diagnosed as having a major depressive episode with a seasonal pattern.

The most common type of seasonal pattern is one in which an individual first experiences symptoms in the late fall, has continued and heightened symptoms in winter, and then experiences a remission of symptoms in the spring. However, other patterns are possible. For example, a person may become depressed in the summer and then become less depressed when the weather becomes colder.

Causes

Lack of sunlight, normally associated with winter, is considered to be the primary cause of SAD. Although winter temperature may also have an impact, especially in colder areas, the lack of light is most important. This is supported by the effectiveness of therapy in which individuals are exposed to high-intensity light (light therapy). The causes of rarer types of seasonal symptoms, such as those experienced by individuals who become depressed in summer, are more difficult to determine.

Symptoms

The symptoms experienced by people with SAD are similar to some of those experienced by depressed people in general: change in appetite, weight gain or loss, fatigue, reduced energy, irritability, and avoidance of social situations. To meet the diagnostic criteria for the disorder as indicated in the DSM-IV-TR, these symptoms must be present during the season the individual is depressed and must lessen or abate when that season is over.