Turns out your coffee addiction may be doing your brain a favor

3/22/2026 at 3:52:34 PM

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...

by tmoertel

3/22/2026 at 4:41:47 PM

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

by hallway_monitor

3/22/2026 at 5:44:38 PM

Thanks for your kind words! And thanks for reporting the typo (now fixed).

by tmoertel

3/22/2026 at 2:44:56 PM

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%).

by jader201

3/22/2026 at 3:08:21 PM

> the relative reduction is less impactful (e.g. 4% to 3.28%

That's also an 18% reduction

by weird-eye-issue

3/22/2026 at 3:33:11 PM

I think what he means is a reduction of 18% based on 4% is way less than 18% based on 80%.

by Xunjin

3/22/2026 at 3:51:40 PM

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%

by infinitewars

3/22/2026 at 5:28:48 PM

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.

by jader201

3/22/2026 at 3:51:41 PM

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?

by foobarian

3/22/2026 at 3:55:58 PM

You just described brussels sprouts !

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

by 4gotunameagain

3/22/2026 at 4:29:45 PM

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!

by crowbahr

3/22/2026 at 5:01:04 PM

They are not genetically engineered, it’s mostly just selective breeding.

by wodenokoto

3/22/2026 at 4:07:52 PM

Especially when you drizzle them with balsamic vinegar!

by PeterWhittaker

3/22/2026 at 4:25:49 PM

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.

by antonvs

3/22/2026 at 1:54:21 PM

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)

by rf15

3/22/2026 at 2:43:43 PM

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.

by CuriouslyC

3/22/2026 at 2:57:55 PM

> 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.

by johnisgood

3/22/2026 at 3:47:16 PM

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

by Jeff_Brown

3/22/2026 at 2:48:19 PM

The studies compared people from the same occupation, so no, that is not likely the reason

by sumeno

3/22/2026 at 3:23:05 PM

But that can still not account for cultural/work ethic differences.

by rf15

3/22/2026 at 2:22:00 PM

Exactly. Just another “study” finding a correlation without causation.

by adrithmetiqa

3/22/2026 at 3:59:55 PM

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.

by citadel_melon

3/22/2026 at 2:16:46 PM

Then again if you have dementia, you are highly likely to lesve the office environment and any study, thus reversing causality.

by cineticdaffodil

3/22/2026 at 3:23:19 PM

Does not apply to the White House

by codyb

3/22/2026 at 1:05:28 PM

Original source: https://jamanetwork.com/journals/jama/article-abstract/28447...

by cebert

3/22/2026 at 3:19:48 PM

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.

by trollbridge

3/22/2026 at 3:49:51 PM

- 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

by throawayonthe

3/22/2026 at 3:12:36 PM

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.

by storus

3/22/2026 at 4:05:34 PM

Caffeine -> Suppresses appetite -> Lowers Caloric Intake -> Reduces Cell Turnover -> Prevents Dementia ?

by mentos

3/22/2026 at 2:19:24 PM

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.

by steve_taylor

3/22/2026 at 4:08:44 PM

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.

by XzetaU8

3/22/2026 at 3:12:48 PM

Does decaf have the same effects ?

by qwertyuiop_

3/22/2026 at 3:22:40 PM

You'd be missing out on the anti-inflammatory properties of the caffeine, so maybe it might have some effect?

by HardwareLust

3/22/2026 at 3:34:39 PM

My bowels disagree, caffeine make them feel inflammatory

by Xunjin

3/22/2026 at 3:24:16 PM

No, only caffeinated

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

by sumeno