"Because these benefits were not seen in users of aspirin or other nonsteroidal anti-inflammatory drugs [NSAIDs], the protective mechanism may be specific to ibuprofen," said senior investigator Alberto Ascherio, MD, DrPH, associate professor of nutrition and epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States.

It may be that ibuprofen inhibits glutamate and therefore protects against the hallmark glutamate toxicity that occurs in Parkinson's disease, said Dr. Ascherio.

Earlier research had shown a potential benefit to nonaspirin NSAIDs. Dr. Ascherio and colleagues therefore examined the relationship between Parkinson's disease and the use of ibuprofen, acetaminophen, and aspirin or other NSAIDs in the 146,565 participants of the American Cancer Society's Cancer Prevention Study II Nutrition Cohort.

The investigators identified Parkinson's disease cases with onset that developed in the 8 years after the study started. The participants self-reported the diagnosis, and the investigators confirmed the diagnosis either by contacting the treating neurologists or by reviewing the participants' medical records. In their analysis, the investigators adjusted for several potential confounding factors, such as age, sex, and smoking status.

The investigation involved 1,250,942 person-years of follow-up. During the study period, 413 people developed Parkinson's disease. Compared to nonusers, ibuprofen users had a relative risk (RR) of 0.65 (95% confidence interval [CI] = 0.48-0.88, P =.005). The results were the same when the investigators adjusted for age, sex, and smoking status.

Compared with nonusers, users of less than 2 tablets per week had an RR of 0.73, for users of 2 to 6.9 tablets per week it was 0.72, and for daily users it was 0.61 (P trend =.03). The duration of ibuprofen use had no significant bearing on its protective effects.

Although the study design did not call for direct tracking of the dose per tablet, the typical dose in an over-the-counter ibuprofen tablet is 200 mg. None of the patients were also using prescription-strength ibuprofen, the investigators reported.

When the investigators looked for an effect in users of aspirin, other NSAIDS, and acetaminophen, they found no significant links between use of these drugs and development of Parkinson's disease.

The study was funded by the Michael J. Fox Foundation for Parkinson's Research and the National Institute for Neurologic Diseases and Stroke.


[Presentation title: Nonsteroidal Antiinflammatory Drugs and the Risk of Parkinson's Disease. Abstract P05.073]

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