Drinking at least two cups of coffee a day may help ward off dementia, Harvard researchers have discovered.
A growing body of science suggests dementia, which affects one in 10 adults over 65, could be prevented by forming healthy habits decades before the condition would be diagnosed.
Previous research suggests cutting down on alcohol and processed foods and prioritizing sleep slashes dementia risks, but science is also looking at less conventional methods.
Now, researchers at Mass General Brigham, a Harvard-affiliated hospital, have honed in on caffeine.
In a new study, the team analyzed health data from more than 130,000 Americans, including how often they consumed caffeine from coffee, tea, soda and chocolate.
Over more than 40 years, participants with the highest caffeine intake had an 18 percent lower risk of developing dementia compared to those who consumed little or no caffeine. This added up to two to three cups of coffee or one to two cups of tea per day.
Caffeinated coffee drinkers also had a 20 percent lower risk of cognitive decline, a precursor to dementia, and performed better on cognitive function tests than those who drank little caffeine.
The experts believe caffeine and micronutrients called polyphenols in coffee and tea may reduce inflammation and cellular damage in the brain, warding off cell death and the release of neurotoxins.
Drinking two to three cups of coffee a day could help prevent cognitive decline and dementia, a study suggests (stock image)
Dr Daniel Wang, senior study author and associate scientist at the Mass General Brigham Department of Medicine, said: ‘When searching for possible dementia prevention tools, we thought something as prevalent as coffee may be a promising dietary intervention, and our unique access to high quality data through studies that has been going on for more than 40 years allowed us to follow through on that idea.
‘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. Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.’
The findings comes as Alzheimer’s disease, the most common form of dementia, strikes nearly 7million Americans, with that figure set to nearly double by 2050.
The new study, published Monday in the journal JAMA, used data from 121,700 female registered nurses enrolled in the Nurses’ Health Study, a 50-year ongoing US database, and 51,529 male health professionals in the Health Professionals Follow-Up Study, an ongoing men’s health cohort study.
Women were between ages 30 and 55, with an average age of 64, while men were ages 40 to 75 and had an average age of 65.
Of all participants, 11,033 developed dementia within the study period. Participants were followed for 43 years on average.
The team found both men and women with the highest caffeinated coffee intake had an 18 percent lower risk of dementia compared to those who drank little or no caffeinated coffee. Additionally, 7.8 percent of caffeinated coffee drinkers had cognitive decline compared to 9.5 percent of those who didn’t drink coffee, a 20 percent difference.
Additionally, the team suggested overall cognitive benefits were most pronounced in people who drank two to three cups of coffee or one to two cups of tea per day, adding up to around 300 milligrams. The FDA recommends no more than 400 milligrams daily.
However, there were no benefits to drinking decaffeinated coffee or tea, suggesting caffeine was they key to neuroprotective benefits.
‘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 Yu Zhang, lead study author and PhD student at Harvard Chan School, said.
Caffeine is thought to reduce inflammation in the brain and decrease the build-up of toxic amyloid-beta proteins that contribute to cognitive decline and dementia.
However, outside experts cautioned that more research is needed.
Naveed Sattar, professor of cardiometabolic medicine and an honorary consultant at the University of Glasgow, who was not involved in the study, said: ‘A major concern is residual confounding: unmeasured factors that cannot be fully accounted for.
‘In this case, people who drink moderate amounts of tea or coffee may simply lead more balanced, healthier lives overall, and it may be these broader lifestyle patterns – not the drinks themselves – that relate to better brain health.
‘There is currently no strong evidence from randomized trials that tea or coffee meaningfully improve recognized risk factors for brain health, such as blood pressure, cholesterol, or glucose levels. For these reasons, I would interpret these findings with considerable caution.
‘The fundamentals of protecting brain health remain unchanged: maintaining good cardiovascular risk factors, eating a healthy diet, staying physically active, keeping alcohol intake low, and engaging in regular mental stimulation.’
There were several limitations to the new study, including using self-reported data on diet questionnaires, which is subject to bias, and not specifying methods of coffee brewing, which can affect caffeine intake.
Professor Tara Spires-Jones, Division Lead in the UK Dementia Research Institute, who was not involved in the study, said: ‘This is a well-conducted study that looked at data from a large number of people over many years. However, the study does have important limitations.
‘This kind of observational research cannot prove conclusively that caffeine intake was the reason for lower dementia risk, other factors related to coffee and tea drinking habits could be responsible.’
