Some studies report that people who drink caffeine or coffee in moderate doses have less risk of cognitive decline or dementia but the results are inconsistent and high doses might harm. The safety of caffeine or coffee intake should be considered separately for each individual.
Caffeine is the most commonly consumed psychoactive substance in the world, most often ingested as a natural component of coffee and tea. Caffeine has well-documented stimulatory effects on mental and physical alertness and muscle coordination.
Is it the caffeine or is it the coffee? While most people assume that caffeine is the most beneficial component of coffee, animal and human research suggest this may or may not be the case. It is difficult to distinguish the effects of caffeine from other components in coffee, some of which may protect. Recent animal studies reveal similar benefits between caffeinated and decaffeinated coffee. Indeed, observations in humans suggest that drinking either caffeinated or decaffeinated coffee may decrease the risk of death from heart disease, stroke and diabetes.
Did You Know? Coffee's origins are in Ethiopia, where the word "coffee" derives from the Arabic phrase kahhwat-al-bun, or "wine of the bean". Caffeine was first isolated from coffee in 1820 and its name comes from the French word for coffee, cafe.
Coffee is the primary source of dietary caffeine and most human observational research on caffeine's benefits are based on coffee. Generally, one cup of coffee contains 60 to 180 mg caffeine while one cup of tea contains about 30 to 45 mg . One ounce of chocolate can contain 1 to 30 mg caffeine. The caffeine content of sodas and modern "energy" drinks can range from 25 to 60 mg and higher per 12 oz can. Caffeine is also added to some pain-relieving medications to enhance their effects . Additionally, caffeine is available as a dietary supplement in pill form, often in doses of 100 to 200 mg. For protection against cognitive decline and dementia, there is no evidence for or against caffeine supplements or energy drinks. Adverse health effects have been reported for some energy drinks.
Possibly, based on very limited evidence. No randomized controlled trials have examined whether coffee or caffeine can prevent dementia or cognitive decline and the results from observational studies are inconsistent .
In some studies, people who habitually drink moderate amounts of coffee or caffeine have a lower risk of cognitive decline or dementia but the pattern is not consistent. Some studies have found no protective association; others have found that the benefit is limited to specific groups of people or specific doses. A meta-analysis in 2015 concluded that, if all the observational evidence is combined, caffeine intake from coffee or tea does not have a statistically reliable protective association, despite a trend of an 18% reduced risk of cognitive disorders like dementia, Alzheimer’s, cognitive impairment, or cognitive decline .
Even if long-term coffee intake does protect the brain, a different yet under-studied question is whether high-risk older people might reduce their risk if they start drinking coffee in late life. One Italian study reported that people who recently increased their coffee intake had a higher risk of mild-cognitive impairment, which is sometimes (but not always) a precursor to dementia . On the other hand, a different study reported that people with mild cognitive impairment were much less likely to convert to dementia if they had higher caffeine levels in their blood . More research is clearly needed. It may be very difficult to disentangle coffee or caffeine intake from the characteristics shared by people who consume it, like occupation, general health, or personal genetics.
Bottom line: If you enjoy coffee, it is unlikely to increase your risk of dementia and might even protect your aging brain, particularly if you consume moderate levels, roughly 1-2 cups per day rather than higher doses. If you don’t enjoy coffee, the evidence is too inconsistent to suggest that you start the habit.
Apolipoprotein E4: Few studies have looked at whether the relationship between coffee or caffeine and cognitive decline is different apolipoprotein E4 carriers versus non-carriers. One study reported that the protective association was stronger in E4 carriers; another study found no relationship with APOE4 status (reviewed in ). To learn more about what APOE means to your health, visit our APOE information page.
Possibly, based on very limited evidence.
Few published studies have examined this question in humans. However, one study hints that caffeine may prevent people with mild cognitive impairment (MCI) from progressing to dementia. Scientists measured blood caffeine levels in a group of people with mild cognitive impairment and then followed them over 2 to 4 years, finally evaluating them again to determine who progressed from mild cognitive impairment to dementia and who did not MCI patients who initially had higher blood levels of caffeine (an indicator of their average caffeine intake) were up to 50% less likely to progress to dementia compared with MCI patients who had low blood caffeine levels .
While these results appear promising, they are not conclusive and don't prove that the slower decline was due to caffeine. The slower rate of decline in people with high blood caffeine levels might be due to the caffeine or it might be due to other characteristics shared by those people, such as an active work/social life or sleep quality. People with dementia often suffer sleeping problems and are sometimes taken off caffeine for this reason. However, if caffeine impairs sleep, it could raise the risk of cognitive decline in those people.
Possibly, based on moderate evidence.
The evidence is mixed on whether coffee or caffeine might slow aging or delay death. People who drink 3-4 cups of coffee per day appear to have a lower risk of mortality overall and from cardiovascular disease specifically . No protective association was seen on cancer-related deaths . These conclusions were based on a 2014 meta-analysis of observational studies. However, a few studies reported an increased risk of death at doses of more than 3 cups per day [25-27] or an increased risk of cancer-related mortality  so the right dose, if any, is unclear.
How coffee might yield these benefits or harms isn’t clear. One study reported benefits from drinking either caffeinated or decaffeinated coffee , suggesting that if coffee is protective, it may not be due to the caffeine. One study reported less systemic inflammation in coffee drinkers . Coffee drinking may benefit people with type II diabetes or people at-risk of developing diabetes [28,29] and the American Diabetes Association recommends coffee was as one of many options for a zero-calorie or low-calorie drink.
Caffeine stimulates the human central nervous system. When consumed, it enters the brain quickly and temporarily increases brain activity [3,4]. Moderate caffeine intake can heighten mental alertness and can improve muscle coordination while excessive caffeine intake can cause restlessness, shakiness and insomnia. Besides temporarily enhancing certain cognitive processes, caffeine may also protect the brain from diseases like Alzheimer's, although the evidence to-date is not conclusive . Animal research has identified ways by which coffee and caffeine can protect brains from aging, damage, and disease [5,6].
Caffeine is not the only biologically active component of coffee. Both caffeinated and decaffeinated coffee contain antioxidant and anti-inflammatory compounds, as well as compounds that may directly impact pathways important in dementias like Alzheimer's disease .
Very likely safe for many healthy adults, based on strong evidence.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Moderate caffeine intake (200 to 300 mg per day or 2 to 4 cups coffee) is generally considered safe for healthy people although its effects and safety will vary person-to-person. People with a history of cardiovascular or high blood pressure problems should consult their physician or healthcare provider. The U.K. Food Standards Agency recommends pregnant women not consume more than 200 mg of caffeine per day. People should avoid caffeine when taking the muscle relaxant tizanidine (Zanaflex™) or the anti-depressant fluvoxamine (Luvox™) because of potentially-dangerous side effects. Coffee can sometimes interfere with the absorption of other medications as well [30,31]. Also, caffeine should be avoided with other stimulants like ephedrine.
As with all dietary supplements, the safety of caffeine supplements depends on the actual content of the pill and on the good manufacturing practices of the supplier. Additionally, sleep disruptions can be a risk factor for dementia. It is also important to ensure that the caffeine does not impair sleep quality, which can accelerate cognitive problems.
It is important to consult with your healthcare providers regarding the potential pros and cons of caffeine use (or increasing your consumption). Be certain that initiating changes in your diet will not interfere or adversely interact with your existing medications. Some prescription medications and supplements may change how your body responds to caffeine. It is also important to ensure that the caffeine does not impair sleep quality, which might in turn accelerate cognitive problems.
To our knowledge, there are no clinical trials planned to study caffeine or coffee and risk of cognitive decline or dementia. The observational data on coffee and/or caffeine use versus cognitive decline is mixed so large observational studies are needed to ask which people might benefit from what dose, if any. Some research is underway to identify and study the other components of coffee that might have health benefits. Other studies are needed to better distinguish between coffee that is caffeinated versus decaffeinated or filtered versus unfiltered.
Read a story from Bloomberg News about the search for dementia drugs derived from coffee.
There are several on-line resources of information that can assist you when making decisions about coffee and caffeine supplements.
To stay connected with us, please provide your contact details below. We will share the latest Alzheimer's and related research news, along with information on our signature events.