A follow-up study into the effect of caffeine on people with Parkinson’s disease has prompted a Canadian researcher to reverse his conclusions and announce that drinking coffee has no therapeutic benefit.
The original study, led by neurologist Ronald Postuma of McGill University in Montreal, and published in the journal Neurology, provided daily caffeine doses to people with Parkinson’s to see if these had any effect on two of the disease’s main symptoms: movement difficulties and sleepiness.
The researchers found that up to 600 milligrams of caffeine daily had only a “borderline” effect on sleepiness but significantly improved motor function in 31 test subjects compared to placebo.
In conclusion, Postuma called for further research into the relationship between caffeine and neurological disorders.
Now that extra research has been done – again, led by Postuma – and the results are surprising.
In a study, once more published in Neurology, a larger group of participants – 121, average age 62 – were given either 400 milligrams of caffeine per day, or a placebo.
The participants were followed for between six and 18 months. The shorter periods arose because for those who enrolled first in the study Postuma and his colleagues found no improvement in movement symptoms, nor in overall quality of life, and so decided to end the trial early.
“While our previous study showed possible improvement in symptoms, that study was shorter, so it’s possible that caffeine may have a short-term benefit that quickly dissipates,” says Postuma.
“Regardless, our core finding is that caffeine cannot be recommended as therapy for movement symptoms of Parkinson’s disease.”
Another neurologist, who was not involved in the study, welcomes the findings while acknowledging they were unexpected.
“It is important that promising leads be studied,” says Charles Hall of Albert Einstein College of Medicine in New York.
“It is also important that the disappointing findings like these be shared so new research can focus on other possible treatments instead.”
Coffee – including its best known component, caffeine – is the subject of a wide range of research as scientists try to understand a range of positive therapeutic outcomes attributed to it.
A 2017 review by Regina Wierzejska of National Food and Nutrition Institute, Warsaw, Poland, and published in the Archives of Medical Science, says, “explaining the widely reported link between coffee intake and the incidence of neurodegenerative diseases remains a considerable challenge. So far, none of the numerous hypotheses has been confirmed or rejected”.
Wierzejska points out that “coffee contains many different components, mostly caffeine, polyphenol, trigonelline, niacin, potassium, diterpenes, and acrylamide”.
She concludes: “At present, it seems safe to inform the general public that coffee drinkers need not fear for their health. Possibly, in the future, experts will recommend drinking coffee not only to satisfy individual taste preferences but also to decrease age-related mental deterioration.”
Andrew Masterson is a former editor of Cosmos.
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