What to Know About a New Study on Coffee, Tea, Caffeine and Dementia Risk

For millions of people, the day begins with a cup of coffee or tea. Now, a sweeping new analysis suggests that this daily ritual may be linked to something much bigger: long-term brain health.

Drawing on data from 131,821 adults followed across two large longitudinal studies from 1986 to 2023, researchers found that people who consumed moderate amounts of caffeinated coffee had a significantly lower risk of developing dementia. Over the study period, 11,033 participants were diagnosed with dementia—allowing investigators to compare beverage habits over decades with real-world cognitive outcomes.

The headline finding? Higher intake of caffeinated coffee was associated with an 18% lower risk of dementia compared with little or no caffeinated coffee consumption.

It’s a compelling result—but as always in nutrition science, the details matter.

What to Know About a New Study on Coffee, Tea, Caffeine and Dementia Risk

The Big Picture: What the Study Found

This was not a short-term trial or a small experiment. Researchers analyzed long-term health data collected over nearly four decades. Participants regularly reported their dietary habits, including coffee and tea intake, and were monitored for cognitive decline and dementia diagnoses.

Key Findings at a Glance

131,821 participants were included in the analysis.
11,033 developed dementia during follow-up.
Higher intake of caffeinated coffee was linked to an 18% lower dementia risk.
Caffeinated coffee drinkers also had a lower prevalence of cognitive decline.
The strongest associations were seen at:

- 2–3 cups of caffeinated coffee per day, or
- 1–2 cups of caffeinated tea per day.

Decaffeinated coffee showed no significant association with dementia risk.
The findings show association, not causation.
Researchers attempted to reduce confounding by excluding individuals with major chronic diseases at baseline. Still, as with all observational research, residual lifestyle or health factors may influence the results.

Why Caffeine? Possible Biological Mechanisms

One of the most intriguing aspects of the study is that decaffeinated coffee did not show a protective association, suggesting caffeine itself may play a key role.

Scientists propose several mechanisms that could explain the link:

1. Adenosine Receptor Blockade

Caffeine blocks adenosine receptors in the brain. Adenosine accumulation is associated with fatigue, but it also influences inflammation and neuronal signaling. Blocking these receptors may:

Enhance alertness and synaptic activity
Reduce neuroinflammation
Support neuronal resilience

2. Reduced Amyloid and Tau Pathology

Some animal and laboratory studies suggest caffeine may influence pathways involved in amyloid-beta accumulation, one of the hallmarks of Alzheimer’s disease.

3. Antioxidant and Anti-inflammatory Effects

Coffee and tea are rich in bioactive compounds:

Polyphenols
Chlorogenic acids
Catechins (especially in tea)

These compounds combat oxidative stress and inflammation—two processes strongly implicated in neurodegeneration.

4. Metabolic and Cardiovascular Effects

Caffeine may improve insulin sensitivity and metabolic function in some individuals. Since cardiovascular health and metabolic disorders (such as diabetes and hypertension) increase dementia risk, indirect protective effects are plausible.

That said, these mechanisms remain hypotheses in humans. Observational associations cannot prove that caffeine directly prevents dementia.

Important Caveats: Why This Study Doesn’t Prove Cause and Effect

Even with a large sample and decades of follow-up, this research has limitations.

1. Observational Design

Participants were not randomly assigned to drink coffee or abstain. This means:

Coffee drinkers may differ systematically from non-drinkers.
Lifestyle habits—exercise, diet quality, education level—may influence results.

2. Self-Reported Intake

Beverage consumption was based on participant questionnaires, which can introduce measurement error.

3. Residual Confounding

Although researchers excluded individuals with major chronic diseases at baseline and adjusted for multiple variables, unmeasured factors may remain.

For example:

Coffee drinkers may have higher socioeconomic status.
Tea drinkers may follow different dietary patterns.
Social engagement patterns may differ.

4. Reverse Causation

Subtle cognitive decline can begin years before diagnosis. Individuals in early stages may reduce caffeine intake due to sleep disruption or health changes, making low caffeine consumption appear associated with higher risk.

Future research—including long-term randomized trials or biomarker-based mechanistic studies—would help clarify whether caffeine itself exerts a direct neuroprotective effect.

How Caffeine Fits Into the Bigger Dementia Risk Picture

Experts are clear: no single food or beverage determines brain destiny.

Dementia risk is shaped by a constellation of modifiable factors:

Physical activity
Cardiovascular health
Diet quality (e.g., Mediterranean-style patterns)
Weight management
Sleep quality
Hearing health
Social engagement

Caffeine may be one small piece of a much larger puzzle.

Interestingly, coffee drinkers in many cohorts also show:

Lower rates of type 2 diabetes
Improved metabolic markers
Higher levels of physical activity (in some populations)

These interacting factors may amplify—or partially explain—the observed association.

Should You Start Drinking Coffee to Prevent Dementia?

Not necessarily.

Researchers and independent experts caution against changing your diet solely based on this study. If you already tolerate coffee or tea well, moderate consumption—two to three cups of caffeinated coffee per day—appears safe for most healthy adults and may be associated with cognitive benefits.

However:

Excess caffeine can worsen anxiety or sleep.
Sleep disruption is itself linked to cognitive decline.
Individual responses vary widely.

If you do not currently drink caffeinated beverages, there is insufficient evidence to recommend starting purely for dementia prevention.

The Motivating Takeaway

What this study reinforces is not a miracle cure—but a hopeful message:

Your daily habits matter.

Over decades, small, consistent behaviors—like moderate coffee consumption, regular exercise, nourishing food, and cardiovascular care—can shape long-term brain health.

Coffee and tea may offer a modest protective association. But the most powerful strategy remains holistic:

Move your body.
Protect your heart.
Prioritize sleep.
Stay socially connected.
Manage hearing and metabolic health.
Maintain a nutrient-rich dietary pattern.

Think of caffeine as a possible ally—not a silver bullet.

Your brain’s future is built cup by cup, step by step, choice by choice.