Bipolar disease could be one of the markers of Parkinson’s disease that Neurology and Neuroscience have been looking for. Huang et al completed a study with impressive results about the associations between bipolar disorder and Parkinson’s disease. Although associations between depression and Parkinson had already been proved, this was the first time that a nationwide longitudinal study tested links between bipolar disorder and Parkinson’s disease in a strict epidemiological study.
The study of Huang et al showed a higher risk of presenting Parkinson’s disease among those with bipolar disease than among those in the control group, The chance was 0,7% in those with bipolar disease and 0,1% in controls. That is a sevenfold increase in risk.
Even though the research had a very rigorous methodology, some details must be considered regarding the results. First, other psychotic syndromes which take place at varying ages can be linked to Parkinson’s disease. Many of these take place in the context of depression and anxiety. The use of some antipsychotic medications could lead to a false positive. The older antipsychotics such as haloperidol and chlospromazine, as well as some mood-stabilizing drugs as lithium and valproate often lead to movement disorders which may resemble parkinsonism. One restriction of the Huang et al study was the genetics of the subjects. Albeit it is a broad study, it is restricted to one location and its population.
These findings could have several implications in day to day clinical practice. Bipolar disorder could seem like a first indicative, a prodromic phase of Parkinson’s disease, giving doctors a chance to start earlier disease-modifying therapies.
Bruna Correa Antochevis Machado
Mao-Hsuan Huang, Chih-Ming Cheng, Kai-Lin Huang, Ju-Wei Hsu, Ya-Mei Bai, Tung-Ping Su, Cheng-Ta Li, Shih-Jen Tsai, Wei-Chen Lin, Tzeng-Ji Chen, Mu-Hong Chen. Bipolar disorder and risk of Parkinson disease: A nationwide longitudinal study. Neurology 2019;92:e2735-e2742