Drinking just two or three cups of coffee each day is enough to slash the risk of dementia by 18 percent and preserve cognitive function for both men and women, researchers said Monday.
And men and women who drink one or two cups of tea a day also saw similar results, according to a new study of more than 131,000 people.
The key lies in the caffeine, according to scientists at Mass General Brigham, Massachusetts Institute of Technology and the Harvard T.H. Chan School of Public Health.
Previous research on caffeine has been mixed, with some studies showing beneficial effects of caffeinated coffee on the brain and others asserting caffeine was harmful. But the researchers say that their findings suggest that the chemical has brain-protecting benefits.
“While our results are encouraging, it’s important to remember that the effect size is small and there are lots of important ways to protect cognitive function as we age,” Dr. Daniel Wang, an assistant professor at Harvard Medical School, explained in a release. “Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.”
A jolting difference
The study included data from 131,821 U.S. participants collected over more than 40 years as a part of Harvard’s Nurses’ Health Study and Health Professionals Follow-Up Study.
The participants underwent assessments of their diet, dementia and cognitive status.
The researchers then compared and analyzed how their coffee and tea intake - including decaffeinated beverages - may have affected each patient over the years.
Coffee is America’s most popular beverage. Two-thirds of American adults drink coffee each day, according to the National Coffee Association.
Overall, they found that caffeinated coffee drinkers had a lower prevalence of cognitive decline than those who drank little or no caffeinated coffee.
The people who drank the most coffee a day had the lowest incidence rate of dementia compared to people who drank the least, with 141 of the top coffee drinkers people developing the condition out of every 100,000 versus 330 people per 100,000, respectively.
Caffeinated coffee drinkers also had better performance on tests of cognitive function, the researchers found.
“Higher tea intake showed similar results, while decaffeinated coffee did not — suggesting that caffeine may be the active factor producing these neuroprotective results, though further research is needed to validate the responsible factors and mechanisms,” Mass General Brigham said.
More than 11,000 participants still developed dementia.
A ticking clock
More than seven million Americans are living with dementia, and that number is expected to nearly double by 2050, according to the Alzheimer’s Association.
There is no cure for dementia, but there are ways to slow disease progression. That’s why early detection and prevention efforts are crucial, the researchers say.
For example, a healthy diet and exercise are associated with reductions in dementia risk.
Just 35 minutes of moderate-to-vigorous exercise a week was linked to a 41 percent lower risk of developing dementia over four years, according to the Johns Hopkins Bloomberg School of Public Health.
And the Mediterranean-adjacent MIND diet has been identified as effective in reducing dementia risk, Columbia University researchers say.
Of course, one of the risk factors for dementia is genetic.
Fortunately, the new study showed the benefits of coffee or caffeine were able to surpass that hurdle, Yu Zhang, a Ph.D. student at Harvard Chan School and a research trainee at Mass General Brigham, said.
“We also compared people with different genetic predispositions to developing dementia and saw the same results — meaning coffee or caffeine is likely equally beneficial for people with high and low genetic risk of developing dementia,” said Zhang.
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