Understanding Bipolar Disorder: The Basics
The illness is sometimes linked to seasonal affective disorder, with depression occurring in late fall or winter, giving way to remission in the spring, and progressing to mania or hypomania in the summer.
About one in five cases of bipolar disorder begins in late childhood or adolescence, referred to as early-onset bipolar disorder. Adolescents are more likely than adults to have more frequent mood swings, mixed episodes, and relapses, and they are more apt to be misdiagnosed. Usually, however, the illness strikes during early adulthood and the average onset is before age 25. The first episode in males is likely to be manic. The first episode in females is typically depressive (and frequently, a woman will experience several episodes of depression before a manic episode occurs). As patients grow older, recurrences of either bipolar I or bipolar II tend to come more frequently and last longer.
Bipolar disorder is thought to result from abnormal functioning of certain brain circuits, which may in part be related to abnormal functioning of genes. Possible chemical abnormalities related to brain circuit dysfunction are not fully understood, but may be related to serotonin, norepinephrine, dopamine, glutamate, and gamma-aminobutyric acid (GABA), among others. The likelihood that genes play a role is supported by the fact that there is sometimes a family history of recurrent mood disorders or suicide.