People with Parkinson’s disease have significantly lower levels of caffeine in their blood than people without the disease, even if they consume the same amount of caffeine, according to a study published in Neurology, the medical journal of the American Academy of Neurology. The researchers suggest that testing caffeine blood levels may provide a simple way to help diagnose Parkinson’s.
The study looked at 108 people who had been diagnosed with Parkinson’s an average of about six years earlier and 31 people without the disease. The two groups were the same age and consumed about the same amount of caffeine, and there were no genetic differences in caffeine-related genes between them. The researchers performed blood tests to measure levels of caffeine and 11 caffeine byproducts and discovered that study participants with Parkinson’s had significantly lower blood levels of caffeine and nine of the 11 byproducts of caffeine.
According to the researchers, the blood tests can reliably diagnose early Parkinson’s with a score of 0.98 where a score of 1 identifies all cases correctly. They also noted two caveats of the research: People with advanced Parkinson’s were not included in this study, and participants with the disease were all taking Parkinson’s medication, which could interfere with caffeine metabolism.