Bipolar Disorder patients at increased risk for Parkinson disease: JAMA Neurology

Delhi: Patients with bipolar disorder (BD) are at increased risk of Parkinson's disease (PD) compared with the general population, according to a recent study.

Findings of the study, published in the JAMA Neurology journal highlight the probability that BD may be associated with later development of PD and the importance of the differential diagnosis of parkinsonism features in people with BD.

According to NIHM definition, bipolar disorder is a brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks.

"Despite the pathophysiology of BD being uncertain, there is a putative role of the dopaminergic system, as levodopa has been shown to induce hypomania or mania in patients with BD,2 and antipsychotic medications that block dopamine receptors can improve manic symptoms," write the authors. "The standard treatment for BD that includes lithium, antipsychotic medications, and antiepileptic medications may be associated with drug-induced parkinsonism, which is not clinically distinguishable from Parkinson disease (PD), both being characterized by bradykinesia, resting tremor, rigidity, and postural instability."

Joaquim J. Ferreira, Laboratory of Clinical Pharmacology and Therapeutics, Lisbon, Portugal, and colleagues assessed the association of BD with a later diagnosis of idiopathic PD.

For the purpose, the researchers searched for online databases from inception to May 2019 using the terms Parkinson disease, bipolar disorder, and mania. Studies that reported data on the likelihood of developing PD in BD vs non-BD populations were included. Two review authors independently conducted the study selection.

Key findings of the study include:

• Seven studies were eligible for inclusion and included 4 374 211 participants overall.


• A previous diagnosis of BD increased the likelihood of a subsequent diagnosis of idiopathic PD (odds ratio, 3.35).


• A sensitivity analysis was performed by removing the studies that had a high risk of bias and also showed an increased risk of PD in people with BD (odds ratio, 3.21).


• Preplanned subgroup analyses according to study design and diagnostic certainty failed to show a significant effect.

"The main clinical implication of this review should be to underline that if patients with BD present with parkinsonism features, this may not be drug-induced and may recommend the investigation of PD. To clinically distinguish parkinsonism from PD in clinical practice, the use of functional neuroimaging methods may be of particular interest, as PD classically presents with nigrostriatal degeneration while drug-induced parkinsonism does not," concluded the authors.

More Information: Risk of Developing Parkinson Disease in Bipolar Disorder: A Systematic Review and Meta-analysis published in the JAMA Neurology journal.

DOI: 10.1001/jamaneurol.2019.3446

Journal Information: JAMA Neurology