Researchers from the University of Miami found that people who get sick from Parkinson’s disease were more likely to be non-smokers and consume large amounts of caffeine.

The patients were evaluated in comparison to their family members who did not develop the disease. The reason of the finding has not been found.

Previous studies suggested that the use of nonsteroidal anti-inflammatory drugs had a protective effect against Parkinson's disease but the latest study did not back up these suggestions.

These findings help scientists to limit the numbers of unknown genetic and environmental factors involved in genetic studies of Parkinson's.

The study included 356 cases and 317 family controls who self-reported environmental exposures. Gender and age at examination were considered important confounders in the analyses. Doses and duration of exposures were determined, and intensity was calculated as the result of dosage and duration.

Parkinson's sufferers were found to be less likely ever smoking in comparison to their unaffected relatives. Additional measures of smoking revealed significant inverse associations with Parkinson's. Increasing intensity of total coffee drinking was also inversely associated with Parkinson's disease. However, there was no significant link between NSAID use, like aspirin, ibuprofen, and naproxen, and the disease.

These are the first examination of the association between Parkinson's disease and caffeine in a case-family control setting. The results may not be generalizable at the population level but the persistence of significant inverse associations for smoking and caffeine suggests that these associations are likely not confounded by familial influences on exposure.

This evaluation of potentially inversely associated risk factors for Parkinson's implicates smoking and caffeine as important environmental exposures even in families with Parkinson's disease. Smoking and caffeine may be modifying genetic effects in these families and should be considered as important covariates in genetic studies, the researchers reported.