Caffeinated Coffee and Cognitive Health: Evidence from a New JAMA Study

by Nils Osmar

The information in this article is not intended as, and should not be taken as, medical advice. Interventions like exercising, dietary changes, and taking medications and supplements can have both benefits and side effects, Please consult with a medical professional about any medical concerns.  See full Medical Disclaimer

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A major new study published in JAMA in February 2026 examined whether drinking coffee and tea is connected to dementia risk. The study followed 131,821 people over up to 43 years, tracking 11,033 cases of dementia during that time. The findings suggest that people who regularly drink caffeinated coffee show notably lower dementia risk, while people who drink decaffeinated coffee do not show this same benefit.

What the study measured

The researchers tracked three different ways of looking at brain health:

1. Dementia diagnosis (the main outcome): Participants were followed through medical records and death certificates to see who developed dementia.
2. How people felt about their thinking: Participants answered questions about whether they noticed their memory or thinking getting worse.
3. Actual cognitive testing: A group of participants took formal tests of memory and thinking skills over the phone, including standard tests like the Telephone Interview for Cognitive Status.

This approach is solic because it captures both what people notice about their own cognition and what actual testing shows about their thinking abilities.

The protective benefit

In a nutshell, the study found that people who drank the most caffeinated coffee showed meaningful differences across all three measures compared to those who drank the least:

Dementia risk: The difference was substantial. People with the highest caffeinated coffee intake had 141 cases of dementia per 100,000 people per year, compared to 330 cases per 100,000 people per year in the group that drank the least coffee. This is an 18% lower risk. The study states: “Higher caffeinated coffee intake was significantly associated with lower dementia risk.”

How people felt about their thinking: The group that drank the most coffee reported noticing memory problems less often. In the high coffee group, 7.8% reported noticeable thinking problems, compared to 9.5% in the low coffee group.

Actual test performance: When people took formal thinking tests, those who drank more coffee scored measurably higher. The differences were not huge in size, but they were real and measurable. The improvement in overall thinking scores was clear, though improvements in one particular test came close to but didn’t quite reach the standard level of certainty researchers use.

The researchers concluded that “greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels.”

Decaf did nothing

This finding tells us something important. The study looked at three things separately: caffeinated coffee, decaffeinated coffee, and tea. Decaffeinated coffee showed no benefit—no lower dementia risk, no better thinking scores. This suggests that something about caffeine itself is what matters, not other things in the coffee plant.

Caffeinated tea showed similar benefits to caffeinated coffee, which further supports caffeine as the active ingredient.

The sweet spot: 2 to 3 cups per day

Here’s something practical: the benefits did not keep growing the higher people drank. Instead, the biggest improvements happened at moderate amounts—around 2 to 3 cups of caffeinated coffee per day, or 1 to 2 cups of tea per day. This means you don’t need to drink large amounts to get the benefit, and drinking a lot more did not provide extra protection.

What we know, and don’t know

The study does not explain how caffeine might protect thinking. Scientists have ideas—caffeine might affect how the brain uses certain chemicals, or it might have anti-inflammatory effects—but these are not part of what this study demonstrated. Any explanation of exactly how it works would be guessing based on other research, not based on this study itself.

Caveats and limitations

The study shows association, not proof: This study followed people’s natural habits and watched what happened. It is not a controlled experiment where some people were assigned to drink coffee and others were not. This means we can say that people who drink more coffee tend to have lower dementia rates, but we cannot say with certainty that the coffee is the reason. It’s possible that people who drink moderate amounts of coffee also have other healthy habits.

People reported their own coffee drinking: Researchers asked people how much coffee they drank every 2 to 4 years using questionnaires. This relies on people remembering accurately, which can introduce some error. However, because the information was collected before people developed dementia, it’s less likely that memory problems changed how they answered.

The people studied were specific: Both groups studied included college-educated professionals in the United States, and 65.7% were women. The findings might work differently for other kinds of populations.

The improvements in test scores were small: While the reduction in dementia risk was meaningful, the actual improvements people showed on thinking tests were modest, even if they were measurable.

Not everyone was the same: The study did not report whether all people showed the same benefit, or whether some groups of people (for example, people with family history of dementia) got more or less benefit.

Where we need to be careful

The study’s message is straightforward, but we need to be cautious about drawing too many conclusions from it. For example:

1. “Coffee prevents dementia” vs. what the study shows: The study shows that people who drink coffee have lower dementia rates. But it doesn’t prove that coffee actually prevents it. A clearer way to say it is: “People who drink regular amounts of caffeinated coffee show lower rates of dementia.”
2. Making up mechanisms: People sometimes say that caffeine works by reducing inflammation or improving blood flow to the brain. The study doesn’t actually show this. These are guesses, not findings.
3. Applying it to everyone: The study followed educated professionals with regular healthcare. People in different situations might see different results.
4. “Drink as much as you want”: Some people might think that if 3 cups is good, 10 cups is better. The study shows this is not true—the benefit stops at moderate amounts.
5. Forgetting about individual differences: Some people get anxious from caffeine, some take medications that don’t mix well with caffeine, and some have heart conditions. The study does not address whether the benefits still apply to these groups.

What the study actually shows

The message seems clear: people who drink 2 to 3 cups of caffeinated coffee per day, followed over many years, show lower rates of dementia and better thinking test scores compared to people who drink very little coffee. Decaffeinated coffee does not show this benefit. Tea with caffeine shows similar benefits. More is not necessarily better—the best effects show up at moderate amounts, not high amounts.

Whether this is because caffeine actually protects the brain, or because healthier people are more likely to drink moderate amounts of coffee, or some combination of both, is a question this study cannot fully answer.

What I’m doing

I’m currently drinking 4 cups of coffee a day. I make a little pot of coffee in the morning; it’s a ritual. I enjoy that does seem to have health benefits. I like adding a little heavy cream to it, and about a tablespoon of MCT oil. I don’t add sugar because I don’t want to raise my blood glucose; if I feel like a little sweetener, I’ll add some monk fruit or allulose. I like starting the day in ketosis and fasting till around noon three or four days a week to promote AMPK activation and autophagy, and this protocol works for me. I’m not recommending my protocol to others; as the saying goes, your results may vary. I’m just letting others know what I’m doing for informational purposes

It’s interesting to know that.coffee consumption is also associated with lower mortality in general; see this article: “Drinking Coffee Adds Years to Our Lives”

More from Nils Osmar

• Rekindle School classes in Seattle: Rekindl.e School
• Anti-Aging Youtube channel Pathways to Longevity
• Anti-Aging Facebook group: Anti-Aging and Life Extension
• Another interesting topic: AI Consciousness
• To see all of my articles and videos on all topics, join: Nils Osmar and Friends

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