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Bipolar disorder may increase risk for Parkinson’s disease

Individuals with bipolar disorder may have a higher risk for Parkinson’s disease later in life compared with those who do not, according to study results published in Neurology, the medical journal of the American Academy of Neurology.

“While patients with major depressive disorder were found to have a higher risk of developing [Parkinson’s disease] later in life, few studies have examined the potential role of bipolar disorder ... in the risk of subsequent [Parkinson’s disease],” Mao-Hsuan Huang, MD, of the department of psychiatry at Taipei Veteran’s General Hospital in Taiwan, and colleagues wrote.

Researchers used data from the National Health Insurance Research Database (NHIRD), a database that includes comprehensive information about patients insured under Taiwan’s National Health Insurance program. Adults aged 20 years and older who were diagnosed with bipolar disorder between Jan. 1, 2001, and Dec. 31, 2009, and had no history of Parkinson’s disease or related diseases were included in the study. Study enrollment was considered the time of bipolar disorder diagnosis, and the follow-up period started at enrollment and ended Dec. 31, 2011, or until death.

The frequency of psychiatric admission for manic/mixed and depressive episodes was evaluated to determine the association between these episodes and risk for Parkinson’s disease.

Researchers enrolled 56,340 patients with bipolar disorder and 225,360 age and sex matched patients who served as controls in the study. Those with bipolar disorder had a higher incidence of developing Parkinson’s than the control group (0.7% vs 0.1%, P = .001), and the duration from study enrollment to Parkinson’s diagnosis during the follow-up period was shorter in those with bipolar disorder.

After adjusting for demographic information and comorbidities, researchers found that adult (HR = 12.02; 95% CI, 9.33-15.51) and geriatric (HR = 3.87; 95% CI, 3.05-4.09) patients with bipolar disorder were more likely to develop Parkinson’s during the follow-up period that the control group.

Patients with one to two psychiatric admissions per year for manic/mixed (HR = 4.02; 95% CI, 2.44-6.61) or depressive (HR = 2.67; 95% CI, 1.26–5.66) episodes were at an increased risk for Parkinson’s. Patients with more than two admissions for manic/mixed (HR = 6.29; 95% CI, 4.07-9.73) or depressive (HR = 6.19; 95% CI, 3.18-12.02) episodes had an even greater risk for Parkinson’s.

“Further studies are needed to investigate whether these diseases share underlying processes or changes in the brain,” Mu-Hong Chen, MD, PhD, of the department of psychiatry at Taipei Veterans General Hospital, said in a press release. “Those could include genetic alterations, inflammatory processes or problems with the transmission of messages between brain cells. If we could identify the underlying cause of this relationship, that could potentially help us develop treatments that could benefit both conditions.” – by Erin Michael

Disclosures: The authors report no relevant financial disclosures.