Hold onto that cup o’ joe: Study finds moderate caffeine intake may reduce dementia risk

Caffeine fiends, rejoice: New research from Mass General Brigham suggests drinking coffee and tea in moderation may lower the risk of dementia.

The researchers analyzed data from 131,821 people who participated in the Nurses’ Health Study and the Health Professionals Follow-Up Study. They compared the health outcomes of those who consumed caffeinated coffee and tea with those who drank decaf or no caffeinated beverages over four decades.

Their study, published Monday in JAMA, determined that those who drank two to three cups of regular coffee daily, or one to two cups of caffeinated tea, had lower rates of dementia, slower cognitive decline and more preserved cognitive function.

“I would say it’s the best evidence we have so far on the association of caffeine and cognitive health,” said the study’s lead author Yu Zhang, a research trainee at Mass General Brigham.

The studies that underpinned the research followed nurses for up to 43 years, with assessments of diet, dementia and cognitive function every few years.

About 8% of the 130,000 participants developed dementia. Those with the highest intake of caffeinated coffee had an 18% lower risk of dementia compared with those who reported little or no caffeinated coffee consumption. Those who drank two to three cups of coffee or one to two cups of tea each day had the greatest benefits. There was no increase in benefits among those who consumed more than that.

And no benefits at all were recorded among those who consumed decaffeinated coffee.

“What is surprising is the results for decaf coffee,” Zhang said “We didn’t observe any association between decaf coffee and dementia.”

The researchers emphasized more work is needed to determine whether a causal link exists between caffeine intake and cognitive function.

“It seems to be the primary neuroprotective compound,” Zhang said. “But we cannot say definitely.”

Other possible factors could include lifestyle differences such as diet and exercise. Zhang also pointed out that prior research on caffeine’s cognitive effects has been inconsistent.

Another question the researchers hope to tackle in the future is whether caffeine’s effects may vary depending on how an individual metabolizes the stimulant. While some people can consume caffeinated drinks late in the day and still sleep well at night, Zhang noted that others experience insomnia. Consuming too much caffeine can also contribute to other health risks, including anxiety, rapid heart rate, digestive problems and blood pressure spikes.

Aside from caffeine, coffee and tea contain polyphenols, compounds which scientists believe contribute to heart health, reduced inflammation, improved gut health and lower blood sugar. The researchers said both compounds may contribute to improved cognitive functioning.

The study comes as the number of new dementia cases is expected to double in the U.S. over next few decades amid an aging population. Most current treatments don’t begin until cognitive decline is already underway, so health experts emphasize that prevention is critical. Researchers said a healthy diet and regular exercise are known to be key factors in preserving cognitive function. And based on the study, caffeine could be helpful as well.

That’s likely good news for the two thirds of Americans who drink coffee daily. The  National Coffee Association says the average U.S. coffee drinker consumes three cups a day.