Under the Hood

Parkinson’s And Bipolar Disorder: Is There A Link Between The Two?

The National Institute of Mental Health estimates that nearly 5.7 million adults develop bipolar disorder in the U.S. every year. Researchers said that these people may also be at risk of Parkinson's disease later in life. 

People commonly start to show signs of bipolar disorder in their 20s. The condition can be managed with antipsychotic medication, anti-epileptic medication and lithium, Medical News Today reported Wednesday.

However, studies warned that long-term intake of such medications could lead to drug-induced parkinsonism. This prompt researchers to study a potential link between bipolar disorder and Parkinson's disease. 

The team analyzed findings of earlier studies that involved more than four million participants. The findings, published in JAMA Neurology, suggest that the effects of bipolar disorder could contribute to changes in the body that could lead to Parkinson's. 

Researchers said that problems with the neurotransmitter dopamine occurred in both conditions. Dopamine receptors support multiple neurological processes, including cognition, memory, motivation, pleasure, learning and fine motor control. 

Bipolar disorder is described as cyclic episodes of depression and mania, while Parkinson's disease is known for causing tremors, rigidity and unstable posture. The death of dopamine-producing cells has been linked to the development of symptoms of Parkinson's disease. 

"The findings of this systematic review and meta-analysis suggest that people with [bipolar disorder] have a significantly increased likelihood of later developing Parkinson's disease,” the researchers said in the study. 

However, the study has limitations. Majority of data that indicated the link between the two conditions came from studies with shorter follow-up times and those that reported misdiagnosis of drug-induced parkinsonism and Parkinson's disease.

Two of the studies used also did not differentiate between Parkinson's and parkinsonism. However, the researchers said the analyses that involved longer follow-up times and less misdiagnosis still showed a "strong" connection between bipolar disorder and Parkinson's. 

"The main clinical implication of this review should be to underline that if patients with [bipolar disorder] present with parkinsonism features, this may not be drug-induced and may recommend the investigation of [Parkinson's disease]," the researchers stated. 

The team hopes to see more studies to further understand how people with bipolar disorder would develop Parkinson's later in life.

Parkinson’s The Parkinson’s Foundation estimates that 1.2 million people will be diagnosed with Parkinson’s disease in the U.S. by 2030. Pixabay

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