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Caffeine affects brain dopamine function in patients with Parkinson's disease
Last reviewed: 02.07.2025
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The results of a study published in the journal Annals of Neurology show that consuming caffeine before diagnostic imaging of brain dopamine may also affect imaging results.
Previous research has shown that regular caffeine consumption is associated with a reduced risk of developing Parkinson's disease. However, there is little research examining the effects of caffeine on disease progression in patients who have already been diagnosed.
A study conducted by the University of Turku and Turku University Hospital (Tyks) in Finland examined how caffeine consumption affects dopamine function in the brain over a long period in patients diagnosed with Parkinson's disease. Dopamine function in the brain was assessed using single-photon emission computed tomography (SPECT) to measure dopamine transporter (DAT) binding.
"The association between high caffeine consumption and a reduced risk of Parkinson's disease has been found in epidemiological studies. However, our study is the first to focus on the effects of caffeine on disease progression and symptoms in relation to dopamine function in Parkinson's disease," says Valtteri Kaasinen, professor of neurology at the University of Turku and the study's principal investigator.
Caffeine consumption does not affect Parkinson's disease symptoms
The clinical study compared 163 patients with early-stage Parkinson's disease with 40 healthy controls. Examinations and imaging were performed twice on a subsample, with an average of six years between the first and second imaging sessions.
Changes in dopamine transporter binding in the brain were compared with patients' caffeine intake, which was assessed both by a validated questionnaire and by determining concentrations of caffeine and its metabolites in blood samples.
Results showed that patients with high caffeine intake had an 8.3–15.4% greater reduction in dopamine transporter binding compared to patients with low caffeine intake.
However, the observed reduction in dopamine function is unlikely to be due to a larger reduction in the number of dopamine neurons following caffeine consumption. Rather, it is likely a compensatory mechanism in the brain that has also been observed in healthy individuals following consumption of caffeine and other stimulants.
"While caffeine may offer some benefits in reducing the risk of Parkinson's disease, our study shows that high caffeine intake does not benefit dopamine systems in already diagnosed patients. High caffeine intake did not result in a reduction in disease symptoms, such as improved motor function," says Kaasinen.
Another important finding of the study was the observation that a recent dose of caffeine, for example in the morning before an imaging session, temporarily increases DAT binding values in humans. This may complicate the interpretation of clinically commonly used brain DAT imaging results.
The study results suggest that patients should abstain from coffee and caffeine consumption for 24 hours prior to undergoing DAT diagnostic imaging.