Compared with the general population, patients with bipolar disorder (BD) have an increased risk of developing idiopathic Parkinson disease (PD), study results published in JAMA Neurology suggest.
Published studies that included data on the risk for PD in patients with BD vs the general population without BD were included in a systematic review. A total of 7 observational studies with 4,374,211 patients met the inclusion criteria for the study and were included in a meta-analysis.
In the pooled analysis, a previous BD diagnosis was associated with an increased likelihood of receiving an idiopathic PD diagnosis (odds ratio [OR], 3.35; 95% CI, 2.00-5.60; I2 92%). The researchers removed studies with a high risk of bias to conduct a sensitivity analysis, which demonstrated a persistent increased risk for PD in patients with a previous diagnosis of BD (OR, 3.21; 95% CI, 1.89-5.45; I2 94%).
While a subgroup analysis found an increased risk for PD in patients with BD and >9 years of follow-up (OR, 1.75; 95% CI, 1.36-2.26; I2 0%) and <9 years of follow-up (OR, 5.20; 95% CI, 4.26-6.35; I2 34%), there was not a significant effect in pre-planned subgroup analyses based on study design and diagnostic certainty.
Study limitations were the inclusion of only observational data, as well as the high statistical heterogeneity in the meta-analysis.
“The main clinical implication of this review should be to underline that if patients with bipolar disorder present with parkinsonism features,” the researchers wrote, “this may not be drug induced and may recommend the investigation of PD.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Faustino PR, Duarte GS, Chendo I, et al. Risk of developing parkinson disease in bipolar disorder: a systematic review and meta-analysis [published online October 14, 2019]. JAMA Neurol. doi:10.1001/jamaneurol.2019.3446