Don’t feel bad splurging on that $7 latte the next time you’re in a midafternoon attention slump.
A new study published in The Journal of the American Medical Association (JAMA) this week provides some strong evidence that drinking coffee and tea is linked to a lower risk of developing dementia. The longitudinal research followed a group of around 130,000 people for more than 40 years, collecting behavioral and health information over the course of their lifetimes.
The results paint a clear picture: People with a daily habit of drinking two to three cups of coffee, or one to two cups of tea, demonstrated a lower risk of dementia compared with their less caffeinated peers. People who drank up to five cups of coffee had about a 20% less risk of dementia, while those who drank one or more cups of tea showed a 15% less risk of developing the neurodegenerative condition.
Decaf coffee wasn’t linked to the same benefits, according to the new research. Caffeine is the key ingredient that appears to be providing some protection from cognitive decline for coffee and tea drinkers, possibly through its ability to reduce inflammation in the brain. The molecule we rely on to wake us up in the morning has also shown promise in reducing insulin sensitivity and lowering the risk of type 2 diabetes—a big risk factor for age-related cognitive decline.
While caffeine appears to be the magic ingredient, other substances in coffee and tea have also been shown to positively impact health. “Beyond caffeine, coffee and tea contain bioactive compounds like polyphenols, chlorogenic acid, and catechins, which offer antioxidant and vascular benefits by reducing oxidative stress and improving cerebrovascular function,” the researchers wrote. “Furthermore, tea components such as epigallocatechin-3-gallate and L-theanine may provide additional benefits by enhancing relaxation and neuroprotection.”
Coffee and tea show promise, but questions remain
With such a massive sample size and so many years of data, the new research on dementia and caffeine is about as robust as an Italian dark roast. Still, the study’s design—asking people about their behaviors and tracking their diagnoses—doesn’t lend itself to causal explanations. While the evidence that caffeine provides some neuroprotective effects against one of the most devastating age-related conditions is exciting, scientists still can’t definitively say what causes the decreased risk—they can only say that coffee and tea intake is correlated with less risk.
In the analysis, the research’s authors controlled for participants’ genetic risk of developing dementia, as well as other potential confounding factors such as education, socioeconomic status, smoking, exercise habits, and medication use.
In spite of its scale and depth, the study, funded by the National Institutes of Health, still has a few notable limitations beyond the observational nature of its design. The study exclusively relied on large, gender-divided data sets collected from people who work in health-related jobs, drawing on the Health Professionals Follow-Up Study and the Nurses’ Health Study. It also did not collect granular data about the kind of tea the participants consumed, so it’s not clear if green and black tea are created equal or if only caffeinated tea showed promise for keeping people sharp as they age.
While the link between coffee and reduced dementia risk is promising, more coffee also doesn’t necessarily mean less risk. Researchers found that the positive impact tapered off after two or three cups of coffee and one to two cups of tea—so don’t go ordering that “quad shot” or “black eye” in hopes of squeezing even more benefit out of your caffeine intake. Caffeine raises your heart rate and can raise blood pressure, too, so keeping your body’s full health picture in mind is important.