Added to Favorites
Add to My Favorites
Added to My Favorites
by Michele Shapiro
Updated September 19, 2022
If you don’t feel like a fully functioning human until you’ve inhaled a steaming mug of coffee in the morning, you’re not alone. Sixty-four percent of Americans report drinking at least one cup on average a day, according to a Gallup poll, and the appeal actually increases with age.
While 50 percent of 18- to 34-year olds consume coffee daily, 74 percent of adults 55 and older say they do the same, the poll reports. While the mental jolt you experience after a java fix is very real, research suggests there may be some additional benefits to your morning or midafternoon cup, as well as a few potential drawbacks.
Best part of waking up
First, a quick lesson in why you experience that brain boost about 30 minutes after finishing your first cup: That feeling of being awake and alert results from several chemical interactions in the body. Caffeine, a stimulant, blocks receptors for the chemical adenosine, which normally prevents the release of brain-sparking chemicals. “By blocking adenosine receptors, caffeine temporarily prevents this signal from making you feel sleepy,” despite the continued accumulation of adenosine in the brain throughout the day, says Michael Grider, director of the neuroscience program at High Point University in North Carolina.
Caffeine also affects two key hormones: cortisol and adrenaline. Grinder explains that adrenaline increases alertness, heart rate, blood pressure and body movement. “Cortisol is the body’s main stress hormone, and it increases the body’s stress response.”
In addition, caffeine increases the activity of a group of neurons known as cholinergic neurons, which are involved in attention and arousal, Grider adds. This is another reason for the short-term increase in focus on a test or work project, for example, that is associated with caffeine intake.
All three of these chemical reactions in the brain increase attentiveness. “The more attentive we are, the more we tend to remember,” says James Giordano, a professor in the neurology and biochemistry departments at Georgetown University Medical Center in Washington, D.C. A study published in the Journal of Nutrition found that on tests of mental function, subjects who consumed caffeine had better scores, particularly among older adults. “Indirectly, caffeine is a tool to improve certain types of learning,” Giordano says.
How long does the increased attentiveness last? Research published in Nature Neuroscience shows that caffeine enhances certain memories for up to 24 hours after consumption. “A moderate dose of caffeine can facilitate the short-term retention of information, which then has a good shot of being encoded into long-term memory,” Giordano says. (An important footnote is that, in scientific jargon, “short-term memory” is between seven and 15 seconds, whereas “long-term memory” is measured in minutes and hours, not in years, as you might imagine.)
Additional research suggests that drinking coffee may also help fend off mild cognitive impairment (MCI), the decline in one’s cognitive abilities beyond expected changes related to aging. MCI is often, but not always, a precursor to Alzheimer’s disease. A study from the Journal of Alzheimer’s Disease determined that older individuals who drink one to two cups per day have lower levels of mild cognitive impairment compared with those who don’t drink coffee. (It’s important to note that the same study found that people who hadn’t been regular coffee drinkers beforehand were actually at higher risk for MCI.)
But when it comes to coffee, more isn’t always better. In fact, high doses can have a negative effect on memory and attentiveness, Giordano says. Plus, “the more coffee you drink, the more used to the caffeinated effect you’ll get, and the more you’ll need.”
So what’s the sweet spot to reap the potential brain benefits? The Mayo Clinic recommends up to 400 milligrams daily — about four cups of coffee — for most adults. But how many cups you can safely consume a day depends on several factors, including your size and liver function, says Grider, who adds that genetics and diet can also influence how fast your body breaks down caffeine.
Despite coffee’s potential brain-boosting perks, researchers have also identified some potential drawbacks that might make you think twice before ordering that latte. In one study published in the American Journal of Epidemiology that involved more than 60,000 women, a high coffee intake was associated with minor decreases in bone mineral density. But Grider, for one, is not overly concerned. “Based on the most recent data available, it appears that decreased bone density does not relate to an increase in bone fractures. Therefore, I would say that coffee is fine unless a person already has advanced osteoporosis.”
Coffee’s impact on sleep is a much greater concern. “As we age, our biorhythm shifts earlier and earlier,” says Jeffrey Ellenbogen, a sleep specialist at the Johns Hopkins University School of Medicine in Baltimore. “We tend to go to bed and wake up earlier. Caffeine lasts in our bodies for about seven hours, so that late-afternoon cup of coffee begins to encroach on bedtime, making it hard to fall asleep.”
In some instances, you may want to rethink your overall coffee habit, at least temporarily. This includes when you’re taking over-the-counter (OTC) supplements for weight loss or memory boosting. “Many OTC treatments contain stimulants that, when taken with caffeine, can have negative effects,” Giordano says. In addition, if you are prone to high blood pressure or taking medications for low blood pressure, caffeine might not be a good idea. Lastly, those with acid reflux, cardiac conditions (such as unstable heart rhythms) and disorders of the parasympathetic and sympathetic nervous systems should check with their doctors before consuming, Giordano advises.
One last coffee caveat: Adding lots of sugar and cream to your cuppa joe may counter the brain-boosting benefits while also wreaking havoc with your waistline. So it pays to be mindful about what you’re putting in your coffee as well as how many cups a day you’re consuming.
• “Caffeine and Alcohol Intakes and Overall Nutrient Adequacy Are Associated with Longitudinal Cognitive Performance among U.S. Adults,” The Journal of Nutrition, April 2014. This study used data from 1,305 adults ages 18 to 93 who participated in the Baltimore Longitudinal Study of Aging to determine how caffeine, alcohol and diet related to performance on cognitive tests. Researchers found that in participants 70 and older, caffeine intake was associated with better overall cognitive performance and better verbal memory while alcohol consumption was related to better scores on tests of working memory and attention. Read the full study.
• “Post-study caffeine administration enhances memory consolidation in humans,” Nature Neuroscience, January 2014. In this study, 160 people ages 18 to 30 studied pictures of objects, were given up to 300 mg of caffeine, then tested 24 hours later on their ability to identify the previously seen objects, similar-looking objects and new objects. They found that participants who consumed caffeine were more likely to identify similar-looking objects as such, indicating enhanced consolidation of short-term memories into long-term ones. Read a summary of the study. (A fee is required to access the full study.)
• “Coffee Consumption Habits and the Risk of Mild Cognitive Impairment: The Italian Longitudinal Study on Aging,” Journal of Alzheimer’s Disease, January 2015. Researchers evaluated coffee consumption and mild cognitive impairment (MCI) in 1,445 65- to 84-year-olds from the Italian Longitudinal Study on Aging. They found that participants who regularly drank one or two cups of coffee each day had lower rates of MCI than adults who regularly did not, while participants who started drinking at least one cup during the study had higher rates of MCI than those with a regular habit. Read a summary of the study. (A fee is required to access the full study.)
• “Long-term Coffee Consumption in Relation to Fracture Risk and Bone Mineral Density in Women,” American Journal of Epidemiology, July 2013. This study measured association of coffee consumption and bone density in 5,022 women ages 39 to 95 over two decades. Researchers found 2-4 percent lower bone density in women who drank four or more cups of coffee daily compared with women who drank less than one, though the researchers didn’t measure any difference in likelihood of fracture in the coffee drinkers. Read the full study.