Coffee may help protect Parkinson's disease even in people with genetic risk

The study compared 188 people who had Parkinson's disease to 180 people who did not have the disease; both groups had people with the LRRK2 gene mutation and those without it. Researchers looked at the amount of caffeine in the blood, as well as other chemicals that are produced as caffeine is metabolized in the body, and how it varied among the groups. A total of 212 of the participants also completed questionnaires about how much caffeine they consumed each day.

Among people carrying the LRRK2 gene mutation, those who had Parkinson's had a 76% lower concentration of caffeine in their blood than those who did not have Parkinson's. People with Parkinson's with a normal copy of the gene had a 31% lower concentration of caffeine in their blood than non-carriers without Parkinson's.

Carriers of the gene mutation who had Parkinson's also had lower consumption of caffeine in their diet. The gene carriers with Parkinson's consumed 41% less caffeine per day than the people who did not have Parkinson's, both with and without the gene mutation.

"We don't know yet whether people who are predisposed to Parkinson's may tend to avoid drinking coffee or if some mutation carriers drink a lot of coffee and benefit from its neuroprotective effects," Crotty said.

Crotty noted that the study looked at people at one point in time, so it does not help researchers understand any effect caffeine has over time on the risk for Parkinson's or how it may affect the disease's progression. It also does not prove that caffeine consumption directly causes a lower risk of Parkinson's; it only shows an association.