[Page 518]Bipolar disorders (BDs) encompass a distinct category of mood disorders. Specifically, BD is an impairing condition marked by extreme fluctuations in mood and behavior and periods of both depressive (extremely low mood) and manic (extremely euphoric and/or irritable mood) episodes. Genetic, biobehavioral, environmental, and cognitive factors likely interact to increase risk for the first onset of BD.

For a mechanism that is hypothesized to underlie a disorder to be considered a vulnerability for that disorder, it is necessary to conduct prospective, longitudinal research. Longitudinal studies must assess the proposed vulnerability prior to the first onset of the disorder to demonstrate temporal precedence, or prediction of disorder. This overview of risk factors for BD is limited to those mechanisms that have some degree of prospective, longitudinal ...