If you drink multiple cups of caffeinated coffee or tea every day, you could have as much as a 20 per cent lower risk of dementia than your un-caffeinated peers, a new paper from Harvard and Mass General Brigham researchers suggests.
While any amount of daily coffee or tea consumption led to a reduced dementia risk, the sweet spot appeared to be two to three cups of coffee or one to two cups of tea every day. Study participants who drank this amount had a 15 to 20 per cent lower risk of dementia, the authors told the Star.
But before you use this paper to justify purchasing an espresso machine, unaffiliated experts warn to take its results with a grain of salt (or sugar).
“What it shows is that there is an association (between coffee or tea and dementia risk). But it’s not necessarily cause-and-effect,” said Dr. Roger Wong, a clinical professor of geriatric medicine at the University of British Columbia.
To get their results, the researchers followed more than 130,000 people over the course of 43 years. Their findings were published in peer-reviewed medical journal JAMA on Monday morning. Here’s what it found.
The link between coffee, tea and dementia
“From what we observed, the people who drink caffeine coffee or tea will have much lower dementia risk and better cognitive performance than those who do not,” said Yu Zhang, the paper’s first author and a PhD student at the Harvard T.H. Chan School of Public Health.
“This was only observed for caffeine coffee and tea, but not observed for decaf coffee,” he told the Star.
Unlike previous studies, the authors found no negative effects to consuming too much caffeine — the study participants who drank the most coffee still had an 18 per cent lower risk of dementia compared to those who drank little or no coffee at all.
What’s more, coffee and tea drinkers performed better on tests of cognitive function and had a lower prevalence of cognitive decline — 7.8 per cent of coffee or tea drinkers reported a subjective decline, compared to 9.5 per cent of those who do not.
While the researchers don’t know exactly why this is happening, they have some ideas. Both coffee and tea contain caffeine and antioxidant compounds called polyphenols, which can reduce inflammation and, according to recent research, may help protect against neurodegenerative diseases.
Decaf coffee drinkers didn’t experience any reduction in dementia risk, potentially indicating that caffeine is the active factor in protecting the brain. But more research is needed before we can draw any conclusions.
“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,” said Dr. Daniel Wang, the paper’s senior author, an assistant professor at Harvard Medical School and an associate scientist with Mass General Brigham, in a press release.
“Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.”
Of the 131,821 study participants, 11,033 developed dementia. Notably, coffee or tea consumption was linked to a reduced dementia risk, even among people genetically predisposed to dementia, Zhang noted.
Health Canada recommends adults consume no more than 400 milligrams of caffeine a day, equivalent to roughly three cups of brewed coffee. Adults who are pregnant, breastfeeding or planning to be pregnant should have no more than 300 milligrams, the agency continued.
Too much caffeine can lead to insomnia, irritability, headaches and nervousness, according to Health Canada.
How else can we prevent dementia?
Early prevention of dementia is key, given the limited treatment options we have for the disease today. Fortunately, nearly half of all dementia cases can be prevented or delayed through basic lifestyle changes, research has shown.
There are at least 14 modifiable risk factors for dementia, ranging from social isolation and lower education in early life, to hearing loss and physical inactivity. Preventing dementia later in life starts with establishing healthy habits early, like exercising regularly, building strong social ties and getting hearing aids or eyeglasses when necessary.
“The thing is, you cannot pick and choose. You need to do them all,” Wong noted. “If you do everything, then it is possible to reduce the likelihood of dementia by up to 45 per cent.”
Now that we know how to prevent dementia, we must dismantle the systemic barriers preventing people from accessing care, Wong continued — especially for communities historically underserved by the health system, who may have difficulty being assessed or accessing treatment for hearing or visual loss, for example.
“The big question really is, how can we both as individuals and society make sure that we actually can do that?” he said. “Because it’s one thing to say, ‘Yeah, there’s a problem,’ but what are we going to do about it?”
