Drinking two to three cups of caffeinated coffee each day, or one to two cups of tea, is linked with the lowest risk of developing dementia, according to a major Harvard University study.
The research, published in JAMA, suggests that people who enjoy these popular beverages also tend to have sharper mental skills compared to those who don't drink them at all.
"Greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels," the researchers wrote.
The findings emerged from a data pool of more than 130,000 American health professionals over an impressive 43-year period. It included around 86,000 female nurses and 45,000 men working in healthcare roles across the United States.
Greater consumption of caffeinated coffee and tea was associated with a lower risk of dementia
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Every two to four years, the respondents filled out questionnaires about their eating and drinking habits, including how much caffeinated coffee, decaf, and tea they consumed. They also underwent cognitive tests to measure their mental sharpness.
Over the course of the follow-up period, 11,033 people in the study developed dementia.
Yu Zhang, the study's lead author from Harvard's TH Chan School of Public Health, said identifying lifestyle factors that might influence dementia risk is crucial given the limited treatments currently available. But when it came to the numbers, certain findings stood out.
Those who drank the most coffee appeared to have an 18 per cent lower chance of developing dementia compared to people who barely touched the stuff. The biggest drinkers showed a 16 per cent reduced risk.
Both groups also experienced a slower rate of mental decline over time compared to those who drank the least.
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Among the nurses in the study, higher caffeinated coffee intake was also tied to better performance on cognitive tests, with tea showing similar results.
Here's the interesting bit, though – decaf coffee didn't seem to offer any of these benefits, suggesting caffeine itself might be the key ingredient.
But before you start brewing an extra pot, experts are urging caution about what these findings actually mean.
Both tea and coffee drinkers appear to experience slower cognitive decline
| GETTYDr Susan Kohlhaas, executive director of research at Alzheimer's Research UK, said: "This research doesn't prove that coffee or tea protect the brain. This study shows an association, not a cause-and-effect relationship."
She pointed out that coffee and tea drinkers might differ in other ways that affect brain health, and the study was conducted among similar groups of health professionals, limiting how broadly the results apply.
Prof Tara Spires-Jones from the UK Dementia Research Institute agreed, noting that observational research like this can't definitively prove caffeine was responsible for the lower dementia risk. Other factors linked to drinking habits could be at play.
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