67 pointsby Bender7 hours ago12 comments
  • tmoertel4 hours ago
    The actual study (1) is observational and makes no causal claim, only that there exists a statistical association between caffeine consumption and dementia. Nevertheless, people are apt to misinterpret the finding as “caffeine consumption prevents dementia”:

    Caffeine -> Dementia

    However, the two variables would be correlated if the causal arrow were reversed and dementia influenced the propensity to consume caffeine:

    Caffeine <- Dementia

    And we would also observe the correlation if a person's general health influenced both the propensity to consume caffeine and dementia risk:

    Caffeine <- General Health -> Dementia

    Since caffeine is a stressor, we would expect to see reduced consumption among people with reduced general health. But we would also expect increased dementia among that same group. So the relationships in the diagram immediately above are plausible and would give rise to a spurious correlation between caffeine consumption and dementia risk.

    While studies can try to “control for confounding factors,” it’s easy to overlook or misunderstand the true causal relationships in play, causing spurious correlations. In other words, you can create false “causal” relationships through imperfect identification and control of confounding variables.

    In short, take this article’s claims with a suitable dose of suspicion.

    (1) https://jamanetwork.com/journals/jama/article-abstract/28447...

    • hallway_monitor4 hours ago
      This is an amazing explanation and I am going to keep it on hand for future use. In the first sentence causal is typoed as casual
      • tmoertel3 hours ago
        Thanks for your kind words! And thanks for reporting the typo (now fixed).
  • jader2016 hours ago
    Actual study: https://jamanetwork.com/journals/jama/article-abstract/28447...

    ”After adjusting for potential confounders and pooling results across cohorts, higher caffeinated coffee intake was significantly associated with lower dementia risk (141 vs 330 cases per 100 000 person-years comparing the fourth [highest] quartile of consumption with the first [lowest] quartile; hazard ratio, 0.82 [95% CI, 0.76 to 0.89]) and lower prevalence of subjective cognitive decline (7.8% vs 9.5%, respectively; prevalence ratio, 0.85 [95% CI, 0.78 to 0.93]).”

    So about 18% relative reduction. But if your risks are already low (e.g. active and healthy diet) the relative reduction is less impactful (e.g. 4% to 3.28%).

    • weird-eye-issue5 hours ago
      > the relative reduction is less impactful (e.g. 4% to 3.28%

      That's also an 18% reduction

      • Xunjin5 hours ago
        I think what he means is a reduction of 18% based on 4% is way less than 18% based on 80%.
      • infinitewars4 hours ago
        Percents of percents always felt kludgey.

        Log probabilities (like decibans) unify this to say there is a -0.86 dB risk reduction for everybody.

        https://rationalnumbers.james-kay.com/?p=306

        It makes the math of combining risks easier and works the same even if we're operating near 99.999% or 0.0001%

      • jader2013 hours ago
        That’s exactly my point.

        If someone is high risk, say 20%, then an 18% drop from that is 14.4%. That may justify picking up caffeine.

        But if you’re otherwise healthy, picking up caffeine has diminishing returns, and the downsides may not be worth it.

  • foobarian4 hours ago
    Makes you wonder. Coffee is tasty, so we drink it, and find out much later it also has these awesome side effects. What if there are plants out there that have even better health effects, but we'll never get decades worth of data on their consumption because they taste bad?
    • 4gotunameagain4 hours ago
      You just described brussels sprouts !

      (they too can get quite tasty in the oven though)

      • crowbahr4 hours ago
        Brussels have chemically changed significantly over the past 20 years of genetic engineering - they're more nutritious than ever and are nowhere near as bitter!
        • wodenokoto3 hours ago
          They are not genetically engineered, it’s mostly just selective breeding.
      • PeterWhittaker4 hours ago
        Especially when you drizzle them with balsamic vinegar!
      • antonvs4 hours ago
        They taste bad to some people, apparently. I like them, as well as all the other cultivars of the Brassica oleracea species, like kale, broccoli, cabbage, and cauliflower.
  • rf156 hours ago
    Is that right? Isn't it more related to the fact that people in education/etc. actually drink more coffee for culture reasons but also use their brain more? could that be the actual reason? Because I don't see how all the coffee zombies in my workplace would last longer long term when they're already useless and aggressive today (until they had their coffee)
    • CuriouslyC6 hours ago
      This was a follow-on to a study of nurses showing coffee drinkers have lower all cause mortality.

      Caffeine has been shown to exert effects via adenosine receptor antagonism and influence on cAMP & AMPK pathways. These same pathways are implicated in a lot of issues with aging. Caffeine also has some anti-inflammatory properties and Coffee beans are a strong anti-oxidant though I don't really think that matters much.

      • johnisgood5 hours ago
        > Caffeine has been shown to exert effects via adenosine receptor antagonism and influence on cAMP & AMPK pathways. These same pathways are implicated in a lot of issues with aging.

        That is like saying biological pathways are implicated in aging (because you said "pathways").

        In any case, adenosine receptor antagonism has a pretty weak link if any to aging.

        Additionally, we say that about virtually everything that is herbal, that it has anti-inflammatory properties. You are right, it does not matter at all.

    • Jeff_Brown4 hours ago
      Yes, without a good experiment (maybe a natural one [1]) we can't know. Even if the study controls for everything observable, there may be unobserved differences that lead to the caffeination difference. For instance, even though two people might have the same job, education, etc. the one who is more ambitious, or creative, or hopeful, or simply healthy enough to feel like working more, might drink more coffee.

      https://en.wikipedia.org/wiki/Natural_experiment?wprov=sfla1

    • sumeno5 hours ago
      The studies compared people from the same occupation, so no, that is not likely the reason
      • rf155 hours ago
        But that can still not account for cultural/work ethic differences.
    • adrithmetiqa6 hours ago
      Exactly. Just another “study” finding a correlation without causation.
      • citadel_melon4 hours ago
        Teasing out causation with empiricism is near impossible without eventually needing to rely on occum's razor to some extent or another.

        Reliance on occum’s razor would probably be less needed if this was a random control trial, but still the study would be correlative with alternative explanations still plausible.

        Regarding health, focus on calorie control and getting enough fats/carbs/protein. Eat whole foods that are high enough on the satiety index because they make calorie maintenance more intuitive so you don’t have to count calories if you don’t want to. Those (and maybe a few other tips) are the only things that have a large enough effect for one to determine with almost (only almost, because everything empirical is a confidence interval/correlation) certainty that they’re effective.

        Any study saying that blueberries are “superfoods” or any other hyper-specific food recommendation, I immediately don’t trust it. There just isn’t any organization that would fund a RTC of such a niche finding, especially considering you would need to pay and surveil thousands of people over the course of their whole life to change their diet and stick to it. I don’t think even the NIH is giving out millions of dollars to a research team to find out if blueberries are superfoods.

  • trollbridge5 hours ago
    Coffee, like other beans, is loaded to the hilt with antioxidants, particularly once it’s hyper-concentrated, and the roasting and brewing process eliminates all the mechanisms beans normally use to avoid animals wanting to eat them.
    • throawayonthe4 hours ago
      - coffee seeds are not actually 'beans'

      - caffeine is the main mechanism it uses to deter pests like insects, definitely not removed in the roasting and brewing process

      - like many fruits, they're sweet and nutritious, encouraging larger animals to eat it

      - the stuff marketed as dietary antioxidants still hasn't been shown to improve anything

      what are you talking about

  • cineticdaffodil6 hours ago
    Then again if you have dementia, you are highly likely to lesve the office environment and any study, thus reversing causality.
    • codyb5 hours ago
      Does not apply to the White House
    • 5 hours ago
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  • storus5 hours ago
    Isn't this all about brain hypoperfusion coming from some sort of dysautonomia and/or mitochondrial dysfunction and worse blood vessels as we age? We know that medication that helps blood flow and endothelium improves brain long-term, like sildenafil.
  • mentos4 hours ago
    Caffeine -> Suppresses appetite -> Lowers Caloric Intake -> Reduces Cell Turnover -> Prevents Dementia ?
  • steve_taylor6 hours ago
    Only a few years ago, there was a study showing that regular caffeine use reduces blood flow to the brain by up to 30%, leading to lower brain volume and increased risk of dementia.
  • XzetaU84 hours ago
    Counterpoint

    "Consumption of coffee and tea and the risk of developing neurodegenerative diseases: a cohort study in the UK biobank"

    https://link.springer.com/article/10.1186/s12937-026-01291-0

    Conclusions

    "Excessive coffee consumption was significantly associated with an increased risk of all-cause neurodegenerative diseases and vascular neurodegenerative diseases. The results also showed that tea intake was associated with a reduced risk of all-cause neurodegenerative disease, vascular neurodegenerative disease, other neurodegenerative diseases, and VD. Moreover, coffee and tea had an interactive relationship with all-cause neurodegenerative diseases and AD, with specific combinations significantly associated with reduced risk of disease" onset.

  • qwertyuiop_5 hours ago
    Does decaf have the same effects ?
    • HardwareLust5 hours ago
      You'd be missing out on the anti-inflammatory properties of the caffeine, so maybe it might have some effect?
      • Xunjin5 hours ago
        My bowels disagree, caffeine make them feel inflammatory
    • sumeno5 hours ago
      No, only caffeinated

      > decaffeinated coffee intake was not associated with lower dementia risk or better cognitive performance