A new study finds that people with early Parkinson’s disease have significantly lower levels of caffeine in their blood compared to those without the disease, even if they consume the same amount of caffeine.
The findings, published in the journal Neurology, suggest that testing the blood for caffeine levels may provide a simple way to aid the diagnosis of Parkinson’s disease.
“Previous studies have shown a link between caffeine and a lower risk of developing Parkinson’s disease, but we haven’t known much about how caffeine metabolizes within the people with the disease,” said study author Shinji Saiki, M.D., Ph.D., of Juntendo University School of Medicine in Tokyo, Japan.
Parkinson’s patients with more severe stages of the disease did not have lower levels of caffeine in the blood, suggesting that the decrease occurs in the earliest stages, according to David G. Munoz, M.D., of the University of Toronto in Canada.
“If these results can be confirmed, they would point to an easy test for early diagnosis of Parkinson’s, possibly even before symptoms are appearing,” Munoz said. “This is important because Parkinson’s disease is difficult to diagnose, especially at the early stages.”
The study involved 108 Parkinson’s patients who had the disease for an average of about six years and 31 non-Parkinson’s participants of the same age. Their blood was tested for caffeine and for 11 byproducts the body produces as it metabolizes caffeine. They were also tested for mutations in genes that can affect caffeine metabolism.
Both groups consumed about the same amount of caffeine, with an average of around two cups of coffee per day. However, those with Parkinson’s disease had significantly lower blood levels of caffeine and nine of the 11 byproducts of caffeine in the blood.
In particular, the caffeine level was an average of 79 picomoles per 10 microliters for people without Parkinson’s disease, compared to 24 picomoles per 10 microliters for people with the disease. For one of the byproducts, the level was below the amount that could be detected in more than half of the people with Parkinson’s.
Using statistical analysis, the researchers found that the blood test could be used to reliably identify the people with Parkinson’s disease, with a score of 0.98 where a score of one means that all cases are identified correctly.
In the genetic analysis, there were no differences in the caffeine-related genes between the two groups.
There are a few limitations of the study. First, people with severe Parkinson’s disease were not included, which could affect the ability to detect a link between disease severity and caffeine levels. Munoz also noted that all of the people with Parkinson’s were taking medication and it’s possible that these drugs could affect the metabolism of caffeine.
Source: American Academy of Neurology