Winter birth

How is winter birth related to risk for bipolar disorder?

Researchers have observed the existence of high and low prevalence (total number of cases) and incidence (number of new cases during a specified time frame) pockets for some psychiatric disorders, with rates varying depending on season of birth. These may be related to variances in temperature, precipitation, and sun exposure, however, the underlying mechanisms involved are largely unknown.

What is the evidence for winter birth as a risk factor for bipolar disorder?

Moderate quality evidence finds a small, increased risk of affective psychosis in people born in late winter in the northern hemisphere (January to April). Affective psychoses is a broad diagnostic category that includes bipolar disorder.

August 2021

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Last updated at: 5:25 am, 16th August 2021
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