Bipolar disorder increases Parkinson’s risk 7-fold

  • Huang MH & al.
  • Neurology
  • 22 May 2019

  • International Clinical Digest
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  • Middle-aged individuals with bipolar disorder have a sharply elevated adjusted risk, nearly 7 times higher, for developing Parkinson’s disease.

Why this matters

  • Long-term health consequences of bipolar disorder, its treatment still being clarified.

Key results

  • During follow-up of 2-10 years, Parkinson’s disease incidence: 0.7% in group with bipolar disorder, 0.1% in group without bipolar disorder (P<.001>
  • Adjusted risk sharply elevated for the former (HR, 6.78; 95% CI, 5.74-8.02).
  • Risk still elevated after excluding:
    • First year of follow-up (HR, 5.82; 95% CI, 4.89-6.93).
    • First 3 years of follow-up (HR, 4.42; 95% CI, 3.63-5.37).
    • Individuals with antipsychotic exposure (HRs, 1.46-3.21).
  • Risk for Parkinson’s disease also elevated for individuals with 1-2 annual psychiatric admissions vs fewer than 1:
    • Manic/mixed episodes (HR, 4.02; 95% CI, 2.44-6.61).
    • Depressive episodes (HR, 2.67; 95% CI, 1.26-5.66).
  • Dose-dependent association for all 3 psychiatric conditions: more admissions, higher risk.

Expert comment

  • In an editorial, Gregory M. Pontone, MD, MHS, and Giacomo Koch, MD, PhD, write, “A key question is the mechanistic nature of the reciprocal relationship between mood and movement. In the case of bipolar disorder as a risk factor for PD, identifying the underlying cause of this relationship might allow the early detection of PD and inform the development of disease-modifying therapies that could benefit both conditions.”

Study design

  • Taiwanese population-based case-control study: 56,340 individuals with bipolar disorder, 225,360 age-, sex-matched controls, 2001-2009.
  • Main outcome: Parkinson’s disease.
  • Funding: Taipei Veterans General Hospital; Ministry of Science and Technology, Taiwan.


  • Only patients seeking care for psychiatric conditions captured.
  • Lacking data on certain potential confounders.
  • Some patients taking antipsychotics possibly included in sensitivity analysis.