People suffering from Parkinson's disease are less likely to smoke or consume high doses of caffeine than family members who do not have the disease.

According to the latest research, smoking cigarettes, drinking caffeinated coffee and taking non-steroidal anti-inflammatory (NSAID) medications (such as aspirin, ibuprofen and naproxen) have long been thought to help protect people from developing Parkinson's disease.

However, little family-based research has been done. Studying individuals with Parkinson's disease and their families enables scientists to limit the number of unknown genetic and environmental factors involved in the condition.

Dana B. Hancock, B.S., of Duke University Medical Center and colleagues assessed the associations between smoking, caffeine and NSAID use and Parkinson's disease in 356 Parkinson's disease patients (average age 66.1) and 317 family members without the disease (average age 63.7). Study participants were interviewed by phone to determine their exposure to environmental factors.

"Individuals with Parkinson's disease were .56 times as likely to report ever smoking and .30 times as likely to report current smoking compared with unaffected relatives," the authors write in the April 2007 issue of Archives of Neurology. "Increasing intensity of coffee drinking was inversely associated with Parkinson's disease. Increasing dosage and intensity of total caffeine consumption were also inversely associated, with high dosage presenting a significant inverse association with Parkinson's disease." There was no link found between NSAID use and Parkinson's disease.

Exactly how smoking and caffeine might affect a person's risk of Parkinson's disease is unknown, the authors note. "Given the complexity of Parkinson's disease, these environmental factors likely do not exert their effects in isolation, thus highlighting the importance of gene-environment interactions in determining Parkinson's disease susceptibility," they conclude. "Smoking and caffeine possibly modify genetic effects in families with Parkinson's disease."