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Science

2 To 3 Cups of Coffee a Day May Reduce Dementia Risk. But Not if It's Decaf. (nytimes.com) 109

If you think your daily doses of espresso or Earl Grey sharpen your mind, you just might be right, new science suggests. The New York Times: A large new study provides evidence of cognitive benefits from coffee and tea -- if it's caffeinated and consumed in moderation: two to three cups of coffee or one to two cups of tea daily.

People who drank that amount for decades had lower chances of developing dementia than people who drank little or no caffeine, the researchers reported. They followed 131,821 participants for up to 43 years. "This is a very large, rigorous study conducted long term among men and women that shows that drinking two or three cups of coffee per day is associated with reduced risk of dementia," said Aladdin Shadyab, an associate professor of public health and medicine at the University of California, San Diego, who wasn't involved in the study.

The findings, published Monday in JAMA, don't prove caffeine causes these beneficial effects, and it's possible other attributes protected caffeine drinkers' brain health. But independent experts said the study adjusted for many other factors, including health conditions, medication, diet, education, socioeconomic status, family history of dementia, body mass index, smoking and mental illness.

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2 To 3 Cups of Coffee a Day May Reduce Dementia Risk. But Not if It's Decaf.

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  • Just a reminder that this is a correlation study. It does not mean that ingesting caffeine will reduce your chance of dementia in the same way that the reduction of pirates has not caused climate change.

    It could simply be that people who can afford to spend money on niceties like coffee can afford food and avoid homelessness. Homelessness is highly correlated with death and dementia but that doesn't mean the house itself is preventing dementia.

    • So an interesting follow up study would be if Starbucks coffee is more beneficial than drip at home coffee.

    • by Anonymous Coward
      This is just the latest attempt by coffee pushers to try and make gullible people drink their addictive product
    • by Sique ( 173459 ) on Tuesday February 10, 2026 @06:21AM (#65979588) Homepage
      Hm. I buy a kilogram of black tea for around $10, and it lasts me around two or three month. So there is that.

      Additionally, it's explicitly mentioned:

      But independent experts said the study adjusted for many other factors, including health conditions, medication, diet, education, socioeconomic status, family history of dementia, body mass index, smoking and mental illness.

      • Lucky you, sounds like tea is dirt cheap. I spend $40 on a kg of coffee and it lasts me 3 weeks.

    • Re: (Score:3, Insightful)

      by bjoast ( 1310293 )
      I don't think we need to hear this condescending lecturing about causation and correlation for the billionth time, but thank you.
      • Dude I pull up to a four way stop and fully expect one of the other three people to not completely grasp how this thing works. Some advice is worth repeating because there's another moron born every minute.

        But yah it's right there in TFS too, so ruling on the field stands, everyone gets a car analogy.

    • Of course correlation doesn't automatically equal causation.

      But it suggests it, and makes it a reasonable thing to investigate.

      • Of course correlation doesn't automatically equal causation.

        But it suggests it, and makes it a reasonable thing to investigate.

        Correct. If people injecting or swallowing cyanide die, we can probably decide that the cyanide has something to do with that.

        But for the Correlation does not equal causation crowd, you can inject or consume all the cyanide you want, at least until it is definitively proven through the most rigorous scientific experiments, even then, not until multiple replications of the experiments, and have definite biological mechanisms proven to show that is with no doubt the cyanide and not something else - which

      • Also if the correlation is erased with something as simple as looking at decaf then it is a pretty good indicator that either the caffeine itself or other components titrated out with it are key contributors to the effect.
    • The last paragraph explicitly says they considered that stuff.

      That doesn't mean they did it right, but that objection was addressed in the summary, and we also already all know that.

    • In this case, your example isn't very good. A house would be excellent at reducing death, particularly death due to exposure. Further, there is a well-known confounding variable, that those with dementia self-select for homelessness one way or another.
    • The study EXPLICITLY accounted for socioeconomic status. So unless you are going to claim homeless people make a bunch of money, I doubt that homelessness is a factor.

    • > It could simply be that people who can afford to spend money on niceties like coffee can afford food and avoid homelessness

      I get your point, but worth pointing out that the study was able to extract details like "Drinking decaff isn't enough" which tells me this particular potential cause probably isn't likely.

  • (Doctor) ”Well, your cholesterol levels are elevated, but new studies show I can safely recommend a cup of coffee for you daily.”

    (Sally Starbucks) * whips out trusty 64oz Coffee Chugger Cup * ”OhMyGAWD Holy shit balls YES! This is aweso..”

    (Doctor) ”That means six ounces, stupid. And you wonder why we’re petitioning to put instructions on bottled water.”

  • And they all claim 1) "this is very strong evidence of the benefits of caffeine", followed by 2) "but don't forget, this study is simply correlational"; and then 3) "but it is a very large sample", followed by 4) "but don't forget... it's correlational". Pick a lane, please.
    • by ledow ( 319597 ) on Tuesday February 10, 2026 @06:25AM (#65979594) Homepage

      Try this:

      Everything in moderation.

      Coffee isn't going to hurt you, and can be beneficial. So long as you're not drinking it several times a day, every day, for the entirety of your adult life.

      Same for alcohol. It does actually have some benefits. But in small doses. Not all day, every day, to excess.

      Same for... almost literally anything. Salt. Sugar. Fat. All the stuff that's "bad" according to cheap headline-grabbing press. You need it all in some amount. Just not to excess.

      Same, even, for things like vitamins. No vitamins = you're dead. Enough vitamins = you're fine. More vitamins = you're going to see no benefit and/or have problems (Vit D can be overdosed on, for example).

      Everything in moderation. Eat red meat. It's fine. Just don't eat it every single day for every meal for decades on end.

      And then you realise - that's why you get different answers from these studies, based on who's running them, who's reporting them, what they're testing, and who they are trying to target with the messaging.

      Caffeine has benefits.
      Drinking caffeine to excess outweighs those benefits with downsides.
      The beneficial effect is rather small.
      The counter-effect is rather large.
      Your body consumes more than just caffeine alone.

      Which explains ALL those results you gave, without having any untruths in there. Now replace "caffeine" with pretty much anything - all those things I listed above. Even drinking too much water will kill you (and it's not as much as you might think).

      Everything in moderation, and then you won't have a problem.

      Same for things like cigarettes, even. If you only have a few, it's not going to kill you. But if you're smoking 20 a day for decades on end? Well, hello lung cancer. It's why the most dangerous drugs are often the ADDICTIVE ones. Caffeine included. People have died from drinking too many caffeine-based energy drinks in too short a period of time.

      • by AmiMoJo ( 196126 )

        But cigarettes are highly addictive. Now excuse me, I need more coffee.

      • by Powercntrl ( 458442 ) on Tuesday February 10, 2026 @07:56AM (#65979704) Homepage

        Same for alcohol.

        Actually, that's mostly just wine, and it isn't the alcohol providing any of the supposed health benefits, but the other compounds in the fermented grape juice.

        • Rum rations were issued in the navy starting in 1655, later grog (diluted rum), to improve morale and break up the monotony of life at sea, so it was a great stress-reducer. If it reduces stress and fights, it's good for your health ... again in moderation.
      • by Teun ( 17872 )
        True.
        And then your heart has a problem with caffeine...
        Thank god not everyone needs caffeine free coffee or tea but it does happen.
      • They keep doing studies that show that there's a small health benefit from red wine.

        In between them, studies keep coming out that show zero health benefit from any kind of alcoholic beverage, and in fact, some detriment.

        But none of them show much effect in any direction for lower levels of consumption, isn't that the useful takeaway?

        • They keep doing studies that show that there's a small health benefit from red wine.

          In between them, studies keep coming out that show zero health benefit from any kind of alcoholic beverage, and in fact, some detriment.

          But none of them show much effect in any direction for lower levels of consumption, isn't that the useful takeaway?

          Alcohol makes it possible for ugly people to have children.

      • Everything in moderation.

        You can't just whip out that phrase and wave it around to solve all your problems. What is the moderate amount of water? What is the moderate amount of alcohol (fyi, the negatives outweigh the benefits at all doses)? Moderate amount of salt? Etc... Everything has a different moderate amount and those amounts all dynamically change based on other factors.

        Saying to just keep to moderate amounts is a bullshit argument if you don't specify what those amounts are. It's the opposite of good advice. It mean

        • by ledow ( 319597 )

          Gosh, if only there were RDA's and medical recommendations that have existed for decades, and it were obvious if you're consuming the same thing all day, every day...

      • Everything in moderation. Eat red meat. It's fine. Just don't eat it every single day for every meal for decades on end.

        It is a nice rule of thumb but like most rules of thumb there are many, many exceptions. Such as crack. Or lead. Or gunshot wounds.

        The other trick is to figure out what "moderation" means. That's the big challenge in nutrition work as the data collection is often problematic and the analyses are often even more problematic.

        • Gunshot wounds have been proven to sometimes have a significant protective benefit to health. It all depends on who the gunshot wounds are on.

        • by ledow ( 319597 )

          Here's a tip:

          Don't chew on lead or gunshot wounds.

          Crack? That would come under the "highly addictive" thing and thus is incredibly stupid for that reason.

      • by Ecuador ( 740021 )

        Same for alcohol. It does actually have some benefits. But in small doses. Not all day, every day, to excess.

        Yeah, no, that's wrong. Even small doses are bad. What you are thinking of is probably wine which has some good properties - but you'd really have to remove the alcohol from it to be a net positive.

      • Be moderate in all things, including moderation.
      • Unless you're hitting stupidly large amounts of Vitamin D it's really difficult to overdose on. Vitamins A and B3 are much, much easier to OD on. Now, if you don't get enough K2, larger amounts of Vitamin D can lead to a dysregulation of calcium in your body, but that that is not the same as vitamin overdose.

      • Everything in moderation? F that! Here is some wisdom from an old fart: Too much of anything is just enough. I may be going to hell in a bucket, babe, but at least I'm enjoying the ride!

      • Coffee isn't going to hurt you, and can be beneficial. So long as you're not drinking it several times a day, every day, for the entirety of your adult life.

        II ddoo tthhaatt aanndd iitt''ss ccoommpplleetteellyy ffiinnee..

      • Coffee isn't going to hurt you, and can be beneficial

        It hurts me as I can't tolerate caffeine.

    • by mccalli ( 323026 )
      Also, every year someone pops up to say correlation is not causation. It isn't, but it's a damned good place to start. Like if I'm thirsty, standing at a t-junction and all the people walking from the left are carrying fresh new bottles of water and all the people walking from the right look like the last thing they tried to 'drink' is sawdust...it's not 100% proven that there's a place to get water from in one particular direction, but on the other hand...it's pretty damned well correlated and guess which
  • by Petersko ( 564140 ) on Tuesday February 10, 2026 @06:27AM (#65979596)

    I drink two cups of caffeinated coffee every morning. My working assumption, based on this post, is that this will have saved me from my lost decade of hedonistic alcohol and drug abuse. Maybe I'll up it to three cups.

  • The study seems to center around the benefits of consuming caffeine via coffee. So the obvious question is..was the measured benefit provided by the coffee bean, or just pure caffeine? Relevant question, since I’m pretty sure the kids are vaping caffeine now. Or will soon.

    Bean sucking addicts can’t quite relate to others not liking the taste of coffee, but rest assured there are plenty who would like to understand the benefits of longevity without having to pretend bitter mud water tastes goo

    • Bean sucking addicts can’t quite relate to others not liking the taste of coffee

      But it's actually quite tasty if you add..

      (Rest assured the study didn't include all the sweeteners, toppings, and sprinkles killing people prematurely, so they mean black coffee.)

      Damn, never mind.

  • From the study: " The most pronounced associated differences were observed with intake of approximately 2 to 3 cups per day of caffeinated coffee or 1 to 2 cups per day of tea.".

    You heard it - ditch the coffee, drink some tea.

    (although, in a small voice, I should probably note that while I am British, I don't drink tea. I drink coffee. Damn.)
    • Yeah, and this bit is a red flag suggesting the study doesn't actually prove what it appears to prove, ie this may be a coincidence.

      The thing is... tea contains far less caffeine than coffee. 8oz of brewed coffee contains 96mg of caffeine vs 48mg in the same amount of black tea (https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20049372)

      So basically there's no correlation at all with caffeine in this case, if you have to drink 288mg of caffeine via coffee to get

  • Then you get sleep deprivation, maybe another risk factor in dementia. Torturers use sleep deprivation.

    Sleep and dementia. [alzheimers.org.uk]

    I am off to bed. Wake me up for Spring.

    • If you're lucky, messing with your sleep is the least of your worries. Too much can also can cause a gastrointestinal upset (a heartburn flare-up and/or a case of the shits). That's always fun.
       

    • Then you get sleep deprivation, maybe another risk factor in dementia. Torturers use sleep deprivation.

      Sleep and dementia. [alzheimers.org.uk]

      I am off to bed. Wake me up for Spring.

      Well, maybe. According to the Slashdot sleepyheads, I should have developed dementia years ago. I do 5 hours a night, wake up rested and ready to take on the day.

      I have a strong suspicion that very early Alzheimers sufferers end up with sleep deprivation, rather than the other way around. As if poor sleep is another symptom.

      This is conjecture of course,

      • > I have a strong suspicion that very early Alzheimers sufferers end up with sleep deprivation, rather than the other way around. As if poor sleep is another symptom.

        Generally I believe it's the opposite, anecdotally one of the first signs we saw with one of my relatives was she was napping pretty much all day despite sleeping the night without problems. We were told once the diagnosis had been done that this was a normal sign.

        Alzheimer's non-memory-related symptoms seem to be very similar to depression

        • I've met old ladies who drink tea by the bucket and are as sharp as a pin. Maybe Miss Marple and Jessica Fletcher are on to something?

  • by nospam007 ( 722110 ) * on Tuesday February 10, 2026 @06:51AM (#65979640)

    Mormons, who drink no coffee should have more dementia cases than 'normal' people.:-)

    • This is why most nerds I know are slamming Monster or NOS all day, I guess.
      • This is why most nerds I know are slamming Monster or NOS all day, I guess.

        Two lady friends at work and myself were so addicted to coffee, that we ended up having to withdraw from it after having panic attacks. It isn't permanent - you can start drinking it again after detox, but if you haven't had a caffeine fueled panic attack, you don't want one. You 100 percent believe you are going to die in seconds, but don't know why.

        I went decaf for two months, then shifted back to regular coffee. Since then, I do my 4 cups a day, enforced by the wife, and haven't had a problem since. A

        • I've probably gotten close. Remember chocolate covered coffee beans. I'd get hyper on those. I've always consumed pretty heavy amounts of caffeine either thru tea (plain no sugar iced tea is great), coffee or in college, Mt Dew. I drink tea basically until I go to sleep. No issues. One time though on a ski trip I drank like 5 cups of coffee at late dinner with friends. For the first time in my life, I experienced sleeplessness. Very unpleasant.
          • I've probably gotten close. Remember chocolate covered coffee beans. I'd get hyper on those. I've always consumed pretty heavy amounts of caffeine either thru tea (plain no sugar iced tea is great), coffee or in college, Mt Dew. I drink tea basically until I go to sleep. No issues. One time though on a ski trip I drank like 5 cups of coffee at late dinner with friends. For the first time in my life, I experienced sleeplessness. Very unpleasant.

            Oh yeah, getting hyper is very unpleasant. I like those chocolate covered beans, but I seldom consume them because at my 4 cups, I'm good. But those beans are good too, and I'd eat too many.

            The other unpleasant thing with regards to coffee is that there are a few occasions when I have to stay up over 48 hours, and all the coffee I end up drinking makes me feel like crap. So I end up having a shot of whiskey. Still feel like crap, but at least I can get a little sleep afterwards.

    • Mormons, who drink no coffee should have more dementia cases than 'normal' people.:-)

      Was this the setup for a Mormon joke?

    • I was thinking the same. Sort of the perfect control group. I actually thought Mormon's banned all drinks with caffeine, even cokes etc.
      • Not necessarily a good control group, because Mormons, as a group, also share many other traits with each other, such as a tendency to have large families, and a tendency to marry within the group, leading to genetic similarities compared to the larger population.

    • Not necessarily. Mormons tend to marry within their own circles, leading to genetic similarities more than you would see in the larger population. That genetic similarity could also lead to either higher or lower rates of Alzheimer's, compared to the larger population. They also tend to share a common lifestyle, which could be a contributing factor one way or the other.

  • I'm sure that DRM-controlled coffee pods: https://www.coffeesexploration... [coffeesexploration.com] reduce the risk even more.
    They will even reduce the risk of hair loss and impotence, not to talk about the risk of personal bankruptcy.
    And if I buy a subscription to DRMd coffee pods will even prevent my car from breaking down (even though I don't have a car)

  • Caffeine, in the form of coffee or tea, brings more than just caffeine to the table.

    1) There's a vascular conditioning effect as it causes constriction and later relaxation of blood vessels in the brain - this could plausibly help maintain proper blood flow and prevent slow hypoperfusion from killing brain cells.

    2) There are anti-inflammatory effects from the beverages, and chronic inflammation is another effect of dementia.

    3) The drinks are frequently a cause of social interaction, and increased social act

    • Caffeine, in the form of coffee or tea, brings more than just caffeine to the table.

      1) There's a vascular conditioning effect as it causes constriction and later relaxation of blood vessels in the brain - this could plausibly help maintain proper blood flow and prevent slow hypoperfusion from killing brain cells.

      2) There are anti-inflammatory effects from the beverages, and chronic inflammation is another effect of dementia.

      3) The drinks are frequently a cause of social interaction, and increased social activity also protects against dementia... my personal theory on that being the brain cells don't die from lack of use.

      4) I believe coffee (I don't know about tea) also helps keep your insulin response healthy, meaning a lower risk of diabetes which in turn is a risk for dementia.

      5) While coffee and tea are diuretics, they do at least briefly hydrate you before your kidneys get to work. A lot of people don't stay properly hydrated, so this has to help.

      I believe all of those. "Coffee dates", be it for people getting to know each other for possible romantic reasons, or just friends and coworkers chatting are great.

      And the last one (hydration) is more important than many people think. I do my 4 cups in the morning, plus drink a lot of water. Yeah, I pee a lot, but I'm personally convinced that the kidneys need exercised, and that not having it be too "strong" is better than else wise.

  • by gweihir ( 88907 ) on Tuesday February 10, 2026 @08:59AM (#65979788)

    One is that if you are in that coffee/tea-bracket, you likely do not have to cut back on it. If it is causation, you definitely should not. If it is something else correlated with dementia and coffee (e.g. lifestyle), you also do not have to. Yes, this comes with some uncertainty, but not that much.

  • The last time I drank two cups of coffee in a day, I had to wake up three times at night to pee. My bladder just can't handle that much caffeine anymore. Guess I better embrace my destined dementia demise.

  • by Tablizer ( 95088 ) on Tuesday February 10, 2026 @09:39AM (#65979868) Journal

    I've seen coffee studies come out for many decades, and they tend to arrive in the pattern of good, bad, good, bad, good, bad, good, bad, etc.

    I average it out: coffee is generally harmless, as long as you don't overdo it. If you want coffee, enjoy a cup of joe, otherwise don't. Don't overthink it.

    • by Tarlus ( 1000874 )

      Coffee and tea, in reasonable doses, are only as unhealthy as the shit people add to them

  • She drank coffee morning, noon and night. Has been in memory care for quite a while. Now, she's 98, and grew up during the great depression and the rationing of WWII, so that may have something to do with it.
  • Dietary intake was collected every 2 to 4 years using validated food frequency questionnaires.

    In other words, the input data was very poor. Please accuracy tell me everything you ate in the last 4 years, including the amounts of things such as the amount of salt and pepper you added to each meal and the amount of creamer you added or didn't add to your various cups of coffee across that timeframe.

    If they don't follow this study with another one directly looking at dosing people with just caffeine, then the study is just statistical propaganda.

  • Perhaps it's not about the primary chemical, but the secondary result.
  • Coffee addicts are the most annoying type of junkie.
  • That's like alcohol free beer. I kinda want to slap the author for pointing out that fire is hot and ice is cold. Why would decaff even enter the equation when you could just use water?
  • I would imagine that people who are driven and want to get lots of things done, and thus keep their minds overly occupied all the time, also drink a good amount of coffeee. What I mean is that people who could have lower chance of dementia also drink more coffee. Coffee may not reduce dementia.
  • ...will make me wicked smaht, right?

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