A new systematic review and meta-analysis ask whether bipolar disorder is associated with developing Parkinson’s disease. Although the authors conclude that there is a link, it is a tough question to unpick.
Bipolar disorder (BD), which people once called manic depression, tends to begin around 20 years of age.
Characterized by cyclic episodes of depression and mania, BD affects an estimated 2.8% of adults in the United States each year.
Scientists do not know why BD occurs in some people but not others, although evidence suggests that the dopamine system might play a role.