Caffeine may reduce the risk of Parkinson's disease in people who have a gene mutation associated with the movement disorder, researchers report.
"These results are promising and encourage future research exploring caffeine and caffeine-related therapies to lessen the chance that people with this gene develop Parkinson's," said study author Dr. Grace Crotty, of Massachusetts General Hospital.
"It's also possible that caffeine levels in the blood could be used as a biomarker to help identify which people with this gene will develop the disease, assuming caffeine levels remain relatively stable," Crotty added in a news release from the journal Neurology.
The study was published online Sept. 30 in the journal.
Previous studies have shown that caffeine may protect against Parkinson's in people with no genetic risk factors. This new study focused on a mutation in the LRRK2 gene that increases the risk of Parkinson's.
Not all people with this gene mutation develop Parkinson's disease, so scientists are trying to pinpoint other contributing genetic or environmental factors.
Could coffee -- or its lack -- be one of them?
This study compared 188 people with Parkinson's disease to 180 people without the disease. Both groups had people with and without the LRRK2 gene mutation.
Among people with the gene mutation, those with Parkinson's had a 76% lower concentration of caffeine in their blood than those without Parkinson's. Among people without the mutation, those who had Parkinson's had a 31% lower concentration of caffeine in their blood than those without Parkinson's.
People with Parkinson's who had the gene mutation consumed 41% less caffeine a day than the people with and without the gene mutation who didn't have Parkinson's.
The study assessed people at one point in time, so it doesn't help researchers understand any long-term effect caffeine may have on Parkinson's risk or how it may affect the disease's progression, Crotty noted.
Also, the study doesn't prove that caffeine consumption directly reduces the risk of Parkinson's; it only shows an association.
The Parkinson's Foundation has more on Parkinson's disease.