Prior Head Injury and Risk for Parkinson Disease

Case-control studies have linked head injury and subsequent Parkinson disease (PD), but most have relied on self-reported head injury, which raises concerns about recall bias. To address these uncertainties, Danish investigators conducted a population-based case-control study to determine whether people who have had hospital contact for head injuries have elevated risk for subsequent PD.

Each of 13,695 PD patients who were added to the Danish national hospital register from 1986 through 2006 was matched by age and sex to 5 randomly selected controls. Overall, patients with PD had significantly higher odds of prior hospital contact for head injury (odds ratio, 1.5). This association, however, was almost entirely due to head injuries that occu…