Dopamine Function in Parkinson’s: Caffeine’s Impact

According to a recent international study conducted by the University of Turku and Turku University Hospital in Finland, patients with Parkinson’s disease who regularly consume large amounts of caffeine have altered dopamine function. The outcomes of diagnostic brain dopamine imaging may also be impacted by caffeine intake before the procedure.

Regular caffeine use has been linked to a lower incidence of Parkinson’s disease, according to earlier research. On the other hand, nothing is known about how caffeine affects people who have already received a diagnosis in terms of how their disease progresses.

A follow-up study conducted by Turku University Hospital (Tyks) and the University of Turku in Finland looked into the long-term effects of coffee consumption on brain dopamine function in Parkinson’s disease patients. Single photon emission computed tomography (SPECT) was used to monitor dopamine transporter (DAT) binding to evaluate the brain’s dopamine function. 

“The association between high caffeine consumption and a reduced risk for Parkinson’s disease has been observed in epidemiological studies. However, our study is the first to focus on the effects of caffeine on disease progression and symptoms about dopamine function in Parkinson’s disease”, says Valtteri Kaasinen, Professor of Neurology at the University of Turku and principal investigator of the study.

Parkinson’s symptoms were unaffected by caffeine use.

In a clinical investigation, 40 healthy controls and 163 patients with early-stage Parkinson’s disease were compared. For a subsample, the exams and imaging were done twice, with an average of six years elapsing between the first and second imaging sessions. The amount of caffeine consumed by the patients was measured using a validated questionnaire and by measuring the amounts of caffeine and its metabolites in blood samples. The results showed a correlation between changes in brain dopamine transporter binding and caffeine consumption.

The results showed that compared to patients who consumed less coffee, those who consumed more showed an 8.3–15.4% larger decrease in dopamine transporter binding. It seems doubtful, nonetheless, that a larger decrease in dopamine neurons following caffeine administration is the cause of the observed fall in dopamine function. It is more likely to be a brain mechanism for downregulating compensation, which has also been shown in healthy people after using stimulants like caffeine.

While caffeine may offer certain benefits in reducing the risk of Parkinson’s disease, our study suggests that high caffeine intake has no benefit on the dopamine systems in already diagnosed patients. A high caffeine intake did not result in reduced symptoms of the disease, such as improved motor function.” – Valtteri Kaasinen, Professor of Neurology, University of Turku

Another significant finding of the study was the observation that a recent dose of caffeine, for example in the morning of the imaging session, temporarily increases the person’s DAT binding values. This could potentially complicate the interpretation of clinically commonly used brain DAT imaging results. The research results suggest that patients should refrain from consuming coffee and caffeine for 24 hours before undergoing diagnostic DAT imaging.

For more information: Dietary Caffeine and Brain Dopaminergic Function in Parkinson’s Disease, Annals of Neurology, https://doi.org/10.1002/ana.26957