Caffeine Levels Prove Diagnostic for Early Parkinson's Disease

A team of Japanese researchers demonstrated that serum caffeine and its metabolites were reliable biomarkers for detection of early Parkinson's disease (PD).

A 2013 paper evaluated a total of 13 articles involving 901,764 participants for coffee, eight articles involving 344,895 participants for tea, and seven articles involving 492,724 participants for caffeine. Results revealed a linear dose-relationship for decreased PD risk with tea and caffeine consumption, whereas the strength of protection reached a maximum at approximately three cups/day for coffee consumption overall.

Based on the established link between PD and caffeine, investigators at Juntendo University School of Medicine (Tokyo, Japan) conducted a study on 108 people who had Parkinson's disease for an average of about six years and 31 people of the same age who did not have the disease. Liquid chromatography–mass spectrometry was used to determine serum levels of caffeine and of 11 byproducts the body makes as it metabolizes caffeine. Participants were also tested for mutations in genes that can affect caffeine metabolism.

Results revealed that Parkinson's disease patients had significantly lower blood levels of caffeine and nine of the 11 caffeine byproducts. 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 patients. Measurement of caffeine correctly identified patients with early PD with 98% accuracy. No differences were found in the activity of caffeine-related genes between the two groups.

Absolute lower levels of caffeine and caffeine metabolite profiles are promising diagnostic biomarkers for early PD. This is consistent with the neuroprotective effect of caffeine previously revealed by epidemiologic and experimental studies. "Previous studies have shown a link between caffeine and a lower risk of developing Parkinson's disease, but we have not known much about how caffeine metabolizes within the people with the disease," said contributing author Dr. Shinji Saiki, a researcher in neurology at Juntendo University School of Medicine.

The caffeine study was published in the January 3, 2018, online edition of the journal Neurology.

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Juntendo University School of Medicine