Proximity to Golf Courses and Risk of Parkinson Disease

This observational study found that people living near golf courses, especially those whose tap water comes from groundwater in the same area as a golf course, had significantly higher rates of Parkinson disease. The association was strongest through the drinking water pathway, where people in vulnerable groundwater zones with a nearby golf course had roughly double the odds of developing PD.

From a statistical rigor perspective, the study had several issues related to analysis, for example:

• No multiple-comparison correction was applied across ~8 simultaneous hypothesis tests, meaning the headline distance-band result (< 1 mile, p = .03) and the 2–3 mile band (p = .03) both fail Bonferroni (threshold ≈ 0.006), so the categorical distance findings — the most publicly legible part of the paper — are not statistically defensible as reported.
• The 20:1 case-to-control matching ratio creates a massive urban/rural imbalance (80% urban cases vs. 30% urban controls) that logistic regression adjustment cannot reliably correct when the covariate distribution is this asymmetric — a propensity-score trimmed or restricted analysis would have been far more credible.
• Distance to a golf course as of 2013 is used as a proxy for pesticide exposure occurring potentially decades earlier, with no validation against actual environmental monitoring, pesticide application records, or biological samples — the exposure metric is essentially untested.
• Income imbalance between cases and controls ($63,400 vs. $55,600 median) is never formally tested as an effect modifier