Ibuprofen and lower Parkinson's risk

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Honglei Chen, Xiang Gao, Michael Schwarzschild, Alberto Ascherio and colleagues. The 2003 and 2011 papers (Harvard School of Public Health; Brigham and Women's Hospital) used the Nurses' Health Study and the Health Professionals Follow-up Study. The 2005 paper (Chen at the US National Institute of Environmental Health Sciences, with American Cancer Society authors Eric Jacobs, Marjorie McCullough, Eugenia Calle and Michael Thun) used a separate large US cohort. Funders were not checked.

What happened

Immune activation in the nigra (landmark 52) raised the question: do anti-inflammatory painkillers (NSAIDs, non-steroidal anti-inflammatory drugs) lower risk?

• 2003 (Arch Neurol). 44,057 men and 98,845 women, 415 new Parkinson's cases. Regular users of non-aspirin NSAIDs had a relative risk of 0.55 (95% CI 0.32–0.96).
• 2005 (Ann Neurol). In a different cohort, ibuprofen users had lower risk than non-users: 0.73 for under 2 tablets a week, 0.72 for 2–6.9, and 0.62 for a tablet or more a day (trend p = 0.03). Aspirin, other NSAIDs and paracetamol (acetaminophen) showed no association.
• 2011 (Neurology). 136,197 people, 291 new cases over 6 years. Ibuprofen users had a relative risk of 0.62 (95% CI 0.42–0.93), with a dose-response trend. Pooled with earlier prospective studies, the risk ratio was 0.73 (0.63–0.85). Aspirin (0.99), other NSAIDs (1.26) and acetaminophen (0.86) were not significantly linked. The authors concluded ibuprofen "should be further investigated" as a protective drug.

Why it moved us toward a cure

It is the first population signal that dampening inflammation might protect, and it pointed at one specific, cheap drug. It has not been tested for slowing the disease. It sits alongside later immune work such as landmark 53.

Outcome

Open. Observational data cannot show cause. Ibuprofen users may differ from non-users in other ways, and early Parkinson's might change who takes it. Other studies are mixed (see landmark 52). A ClinicalTrials.gov search on 19 Oct 2026 (condition Parkinson, intervention ibuprofen) returned no study.

Sources

• Chen et al., Arch Neurol 2003;60:1059–1064, DOI 10.1001/archneur.60.8.1059, PMID 12925360
• Gao et al., Neurology 2011;76:863–869, DOI 10.1212/WNL.0b013e31820f2d79, PMID 21368281
• Chen et al., Ann Neurol 2005;58:963–967, DOI 10.1002/ana.20682, PMID 16240369
• ClinicalTrials.gov search, ibuprofen and Parkinson, 19 Oct 2026 (no results)
• Not yet verified: the name of the 2005 cohort; NSAID studies that found no link (the "mixed" statement rests on landmark 52); funders.