Parkinson disease has a complicated relationship with psychiatric disorders. Some medications used to treat this disease can lead to psychosis or compulsive behavior; some psychiatric medications can produce parkinsonian symptoms; and individuals with Parkinson’s Disease can develop psychiatric disorders, especially depression, as part of the neurologic disease. Also, risk for Parkinson’s Disease is elevated in patients with major depressive disorder. To learn about possible connections between Parkinson’s Disease and bipolar disorder, researchers used a large database to examine new diagnoses of Parkinson’s Disease.

Follow-up lasted several years, and it was found that. people with Bipolar Disease had a significantly higher risk for developing Parkinson’s Disease than did the controls. Risk for Parkinson’s Disease was associated with greater frequency of psychiatric admission both for manic/mixed and for depressive episodes. This finding persisted in an analysis excluding patients with antipsychotic exposure before Parkinson’s Disease diagnosis.  These findings suggest that Bipolar Disease, especially more severe illness requiring hospitalization, increases the risk for the development of Parkinson’s Disease. The authors suggest that the two disorders might share an underlying mechanism, such as epigenetics, inflammatory process, or dysfunctions in neurotransmission. Although the study examined the effects of antipsychotic exposure, other medications, including mood stabilizers, might increase Parkinson’s Disease risk. Clinicians should be alert to the development of Parkinson’s Disease symptoms in their patients with Bipolar Disease.