Most Americans—62 percent—love their morning cup of coffee or afternoon pick-me-up, according to a 2022 study by the National Coffee Association. And some of them may wonder about the health benefits. In fact, new research suggests it may be good for the brain, says Marilyn C. Cornelis, PhD, associate professor of preventive medicine at Northwestern University's Feinberg School of Medicine in Chicago. So far, most research shows a link between coffee consumption and a reduced risk of disease but no clear cause and effect.
In particular, studies indicate that coffee is associated with a lower risk of Alzheimer's disease, multiple sclerosis (MS), Parkinson's disease, and stroke. Its relationship to migraine is more complex, but for some people coffee is linked to fewer attacks, says William B. Young, MD, FAAN, professor of neurology at Thomas Jefferson University Hospital in Philadelphia.
Several studies looking at Alzheimer's showed a link between consuming coffee and a reduced risk of the disease. A 2021 study published in Frontiers in Aging Neuroscience found a connection between drinking more coffee and a slower cognitive decline and less accumulation of beta amyloid, a marker of Alzheimer's disease. In another study, published in the Journal of Agricultural and Food Chemistry in 2023, researchers looked at espresso in lab tests and found that the ingredients could potentially stop the clumping of tau proteins linked to Alzheimer's disease. Adding coffee to tau proteins in test tubes appeared to prevent the formation of structures associated with memory loss. In a third study, published in Annals of Neurology in 2022, caffeine intake correlated with lower levels of Lewy bodies in the brain, says Dr. Cornelis. Lewy body dementia is characterized by abnormal deposits of alpha-synuclein, a protein in the brain. “The result suggests that coffee may have an impact on a specific type of dementia,” she says.
To learn more about the link between coffee and Parkinson's disease, a researcher at the National Food and Nutrition Institute in Warsaw, Poland, conducted a meta-analysis of 90 coffee-related studies. The results, published in Archives of Medical Science in 2017, found that men who drank at least one cup of coffee a day had a lower risk of dying from Parkinson's than those who abstained. In addition, male coffee drinkers had a 30 percent lower risk of developing the disease than nondrinkers.
The research on coffee's effect on MS suggests that it may lower the risk of developing the disorder. A study published in the Journal of Neurology, Neurosurgery and Psychiatry in 2016 found that people who didn't drink coffee were about one and a half times as likely to develop MS as those who drank four or more cups of coffee per day. A meta-analysis in 2018 in Frontiers in Nutrition concluded that coffee and especially caffeine in high doses might have a preventive effect on MS.
Evidence for caffeine's potential role in reducing the risk of stroke comes from a study in PLOS Medicine in 2021. Researchers followed 365,682 participants from the UK Biobank, an extensive database and resource for researchers, from 2006 to 2020 and concluded that drinking coffee and tea separately or in combination was associated with a 32 percent lower risk of stroke.
For some people with migraine, caffeine can ease pain in the early stages of an attack. For others, it can trigger a headache or aggravate symptoms, says Dr. Young. Caffeine, which has long been an ingredient in over-the-counter pain relievers, is known to narrow blood vessels, says Dr. Young. During a headache or migraine, blood vessels in the brain may dilate or widen, which contributes to increased blood flow and pressure in the head that can cause pain. Medications that narrow these blood vessels reduce blood flow and can alleviate the associated pain.
People who regularly consume caffeine may become dependent. If they stop completely, they may experience withdrawal, which can trigger headaches. Dr. Young recommends that people pay attention to their bodies' responses to caffeine or talk to a health care professional about whether to start or stop drinking coffee or other caffeinated beverages.
Researchers are still trying to understand how coffee may protect against some neurologic disorders. Its high caffeine content is one clue, says Sandra Weintraub, PhD, professor of psychiatry and behavioral sciences at Northwestern University and associate director of the Northwestern Alzheimer's Disease Research Center in Chicago. When absorbed in the bloodstream, caffeine travels to the brain, where it blocks the action of adenosine, a neurotransmitter responsible for promoting sleep and relaxation, according to a 2021 study published in Cureus. This leads to increased levels of other neurotransmitters like dopamine (a “feel good” messenger) and norepinephrine (the brain's “fight or flight” messenger), which temporarily provide an energy boost and mental alertness.
Despite coffee's potential protective effects, consuming caffeine should be an individual decision, says Dr. Weintraub. “Everybody's looking for the one health tip, like ‘If I eat more blueberries' or ‘If I exercise this particular way,' that will be the secret to a long, healthy life,” she says. “The research can help guide us, but you also have to think about your own body.”
How Much Coffee Is Enough?
The amount of coffee considered “too much” can vary from person to person, says William B. Young, MD, FAAN, professor of neurology at Thomas Jefferson University Hospital in Philadelphia.
However, general guidelines can help provide an idea of moderate and excessive caffeine consumption.
According to the U.S. Dietary Guidelines, moderate caffeine intake for most adults is defined as three to five cups of coffee per day, providing up to 400 milligrams of caffeine. High doses of caffeine are generally considered to be more than 600 milligrams per day, which is roughly equivalent to six or more cups of brewed coffee.
People tend to use “coffee” and “caffeine” interchangeably, but most of us consume caffeine in other ways, says Dr. Young. “You can have two cups of coffee and forget about the two Excedrin you took or the Diet Coke and iced tea you drank,” he says. “Over time, you may be consuming a lot more than you initially thought. It's important to be mindful of that.”
Tolerance to caffeine varies, and some people may be more sensitive to its effects, which can include insomnia, jitteriness, increased heart rate, digestive trouble, and in some cases anxiety, according to the U.S. Food and Drug Administration. People who are pregnant or have certain health conditions, such as insomnia and sleep disorders, anxiety disorders, or gastrointestinal or cardiovascular issues, should talk to their doctors to determine an appropriate level of caffeine intake.
The general rule is to pay attention to how your body responds to caffeine and adjust your intake accordingly, says Dr. Young.
