188 Depressive Disorders
in bipolar I disorder. In some individuals, the onset of manic or hypomanic episodes
may also be linked to a particular season.
The prevalence of winter-type seasonal pattern appears to vary with latitude, age,
and sex. Prevalence increases with higher latitudes. Age is also a strong predictor of
seasonality, with younger persons at higher risk for winter depressive episodes.
Specify if:
In partial remission:  Symptoms of the immediately previous major depressive episode
are present, but full criteria are not met, or there is a period lasting less than 2 months
without any significant symptoms of a major depressive episode following the end of
such an episode.
In full remission:  During the past 2 months, no significant signs or symptoms of the
disturbance were present.
Specify current severity:
Severity is based on the number of criterion symptoms, the severity of those symptoms,
and the degree of functional disability.
Mild:  Few, if any, symptoms in excess of those required to make the diagnosis are
present, the intensity of the symptoms is distressing but manageable, and the symp-
toms result in minor impairment in social or occupational functioning.
Moderate: The number of symptoms, intensity of symptoms, and/or functional impair-
ment are between those specified for “mild” and “severe.”
Severe:  The number of symptoms is substantially in excess of that required to make
the diagnosis, the intensity of the symptoms is seriously distressing and unmanage-
able, and the symptoms markedly interfere with social and occupational functioning.