A new research has found that the caffeine level in the blood may help in the diagnosis of Parkinson's disease.
The results were published on January 3, 2018, and stated the people suffering from Parkinson's disease have a significantly lower level of caffeine in their blood as compared to people not affected by the disease, even if the consumed amount of caffeine is same.
"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 metabolises within the people with the disease", said study author Shinji Saiki, MD, PhD, of the Juntendo University School of Medicine in Tokyo, Japan.
The study was conducted on 108 people who had had Parkinson's for an average of about six years and 31 people of the same age group who did not have the disease. Their blood was tested for caffeine and for 11 by-products the body makes as it metabolises caffeine. They were also tested for mutations in genes that can affect caffeine metabolism.
According to David G Munoz, MD of the University of Toronto in Canada, who authored an accompanying editorial about the study, said the people with more severe stages of Parkinson's did not have lower levels of caffeine in their blood, suggesting the decrease only occured in the earliest stages of the disease.
"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, adding, "This is important because Parkinson's disease is difficult to diagnose, especially at the early stages."
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The coffee consumption for the groups was monitored to the same amount with an average equivalent of about two cups of coffee per day. However, the people with Parkinson's had lower caffeine and 11 by-product levels in their blood. The caffeine level was an average of 79 picomoles per 10 microlitres for people without Parkinson's disease, compared to 24 picomoles per 10 microlitres for people with the disease. For one of the by-products, the level was below the amount that could be detected in more than 50 per cent of the people with Parkinson's disease.
The researchers found that the test could be reliably used to identify people suffering from the disease, with a score of 0.98 where a score of 1 means that all cases are identified correctly, in statistical analysis.
In genetic analysis, they found that there were no differences in caffeine-related genes between the two groups.
Limitations of the study were that the people with severe Parkinson's disease were not included, hence jeopardising the ability to detect an association between severity and caffeine levels. Munoz also noted that all of the people with Parkinson's were taking Parkinson's medication and it's possible that these drugs could affect the metabolism of caffeine.
The research was published in the online issue of Neurology, the medical journal of the American Academy of Neurology.