Published 5th May 2026
Does coffee reduce dementia risk? New study sheds light
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A new study concludes that people who drank caffeinated coffee and tea tended to have a lower risk of dementia.
The association appeared strongest at moderate intakes, rather than “the more, the better”.
Decaffeinated coffee wasn’t associated with lower dementia risk in this research, suggesting caffeine (or something closely linked with drinking caffeinated coffee) may be playing a role.
This was an observational study, so it can’t prove that coffee or tea prevents dementia.
If you already enjoy coffee or tea and tolerate caffeine well, the results are reassuring, but it’s not a reason to start drinking caffeine (or to increase your intake) if it worsens sleep, anxiety, or reflux.
Coffee and tea are two of the most popular drinks in the world, and they’re often linked to brain health in headlines.
A recent study published in JAMA took a look at this relationship. The researchers examined long-term coffee and tea intake and its links to dementia risk and cognitive outcomes.
In this article, we’ll break down what the researchers actually found and what might explain the link.
Just as importantly, we’ll explore what this study can’t tell us, so you can take away something useful without overinterpreting the headlines.
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What did the study look at?
This research followed a large group of adults for up to 43 years to see whether coffee and tea intake were linked with dementia risk and cognitive outcomes.
The researchers tracked intake over time (including caffeinated versus decaf coffee) and recorded dementia cases and cognitive performance during follow-up.
This is called a “prospective cohort study” because it observed real-world habits rather than telling people what to drink. This matters when interpreting what the results can (and can’t) show.
The key findings
The headline result was that higher intake of caffeinated coffee was associated with a lower risk of dementia. Tea intake showed a similar overall pattern for cognitive outcomes.
One of the most useful details for interpreting the results is that decaffeinated coffee did not show the same association.
This doesn’t prove caffeine is the “active ingredient,” but it does suggest the relationship isn’t simply about coffee as a beverage or a general “coffee drinkers are healthier” story.
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The study also suggested a nonlinear dose-response pattern. In other words, the association wasn’t a straight line in which more cups always looked better.
Instead, the most favorable associations were seen around moderate intake, roughly in the range of a couple of cups per day, depending on the drink and how “cups” were defined.
Why might coffee or tea be linked with brain health?
There are a few plausible explanations, and more than one could be true at the same time.
1) Caffeine may play a role
Caffeine affects the brain directly, for example, increasing alertness and attention, and may also influence biological pathways linked with brain aging.
The fact that decaf didn’t show the same positive associations makes caffeine a reasonable candidate, but it’s not definitive.
2) Coffee and tea contain bioactive compounds beyond caffeine
Both drinks contain polyphenols and other compounds that may affect inflammation, blood vessel function, or metabolic health.
Because the brain is closely linked to cardiovascular health, anything that supports vascular function could plausibly be part of the picture.
3) Drinking coffee or tea might be a marker for other lifestyle factors
Even with careful statistical adjustment, observational research can’t perfectly separate the drink from the person drinking it.
Coffee or tea intake may correlate with work patterns, physical activity, diet quality, sleep habits, smoking history, or social routines, all of which can influence dementia risk.
What are the limitations of this study?
Because this was an observational study, it cannot prove that coffee or tea causes a lower dementia risk; it can only show that the two are linked.
Even in large, well-run cohort studies, there’s always the chance of residual confounding.
This means that coffee and tea intake may be associated with other factors, such as overall diet quality, smoking history, or physical activity, which also influence dementia risk.
And these factors aren’t always captured perfectly.
There are also limits to how precisely researchers can measure long-term intake, because dietary data is usually self-reported and can change over time.
So, the most accurate interpretation is that the findings are interesting and plausible, but they shouldn’t be read as proof that increasing caffeine intake will prevent dementia.
Practical advice
If you’re translating this into real life, a balanced takeaway might look like this:
If you already drink caffeinated coffee or tea and you feel good doing so, this study is reassuring, especially around moderate intake.
If caffeine negatively affects your sleep, anxiety, heart rhythm, or reflux, it’s not worth forcing it for a possible benefit suggested by observational data.
If you do drink coffee, what you add matters: coffee drinks that are effectively desserts (syrups, whipped cream, lots of sugar) are a very different health package than black coffee without sugar.
For more information on the healthiest way to drink coffee, try this article next: Are there ‘healthiest’ types and ways to drink coffee?
And you can learn about ZOE’s latest research into coffee and the gut microbiome here.
Alternatively, watch this podcast episode about coffee with Prof. Tim Spector and James Hoffmann:
Summary
A large, long-term JAMA study found that people who consumed more caffeinated coffee and tea tended to have a lower risk of dementia and slightly better cognitive outcomes.
The strongest associations were seen at moderate intake levels, but decaf coffee wasn’t associated with lower dementia risk in the same way.
These findings are interesting and plausible, but they don’t prove that coffee or tea prevents dementia.
The most practical approach is to treat this as reassuring if you already enjoy coffee or tea (and tolerate caffeine well), while still prioritizing the fundamentals that matter most for brain health: good sleep, overall diet quality, movement, and cardiometabolic health.
FAQs
Here are the answers to some commonly asked questions about coffee and dementia:
1) Does coffee prevent dementia?
Not necessarily. This study found an association between caffeinated coffee intake and dementia risk, but because it’s observational, it can’t prove that coffee causes a lower risk.
2) Is decaf coffee just as good for dementia risk?
In this research, decaffeinated coffee was not associated with lower dementia risk as caffeinated coffee was.
That doesn’t mean decaf is “bad,” but it suggests caffeine (or something linked to caffeinated coffee drinking) may matter.
3) How much coffee or tea should you drink for brain health?
The results suggested the most favorable associations at moderate intakes rather than at very high intakes.
In practice, the “right” amount is also about tolerance; if caffeine disrupts sleep or increases anxiety, less is often better.
4) What if coffee makes me anxious or affects my sleep?
Then it may not be a good trade-off. Sleep is strongly linked to brain health, so if caffeine reduces sleep quality, any potential benefit suggested by this study could be outweighed. Consider reducing the quantity, drinking it earlier in the day, or choosing tea/decaf.
5) Does it matter what you add to coffee?
Yes. Sugar-sweetened coffee drinks can add a lot of extra sugar and calories. If you’re drinking coffee for health, it’s generally better to keep it closer to plain (or lightly sweetened) and pay attention to how it fits into your overall diet.
