Bipolar disorder more than triples risk for Parkinson’s disease

  • Faustino PR & al.
  • JAMA Neurol
  • 14 Oct 2019

  • International Clinical Digest
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Takeaway

  • Patients with bipolar disorder were >3 times as likely as individuals in the general population to receive a Parkinson’s disease diagnosis.

Why this matters

  • Findings have implications for prognosis and differential diagnosis.

Key results

  • Diagnosis of bipolar disorder was associated with a sharply elevated likelihood of Parkinson’s disease (OR, 3.35; 95% CI, 2.00-5.60).
  • Findings similar in a sensitivity analysis excluding studies having high bias (OR, 3.21; 95% CI, 1.89-5.45).
  • In subgroup analysis based on duration of follow-up, Parkinson’s disease risk elevated with:
    • Less than 9 years of follow-up (OR, 5.20; 95% CI, 4.26-6.35).
    • More than 9 years of follow-up (OR, 1.75; 95% CI, 1.36-2.26).
  • However, associations were not significant in subgroups stratified by study design or by diagnostic certainty.

Study design

  • Systematic review and meta-analysis of 7 retrospective or prospective cohort studies and cross-sectional studies having 4,374,211 total participants: patients with bipolar disorder and controls (general population, hospital population, or US army veterans).
  • Main outcome: Parkinson’s disease.
  • Funding: None disclosed.

Limitations

  • Possible misdiagnosis of parkinsonism as Parkinson’s disease.
  • Residual confounding.
  • Heterogeneity of included studies.
  • Most did not assess the association as their primary objective.