Caffeine links both coffee and tea to lower dementia risk

To reach this conclusion, investigators from Harvard University, Mass General Brigham, MIT, and other institutes looked at data that was tracked through two large, long-term health studies. First was the Nurses Health Study which tracked data from female registered nurses from 1976 through 2023, and the second was the Health Professionals Follow-up Study which gathered health data from male health professionals from 1986 through 2023.

From these large cohorts, the researchers settled on 131,821 participants to include in a meta-analysis. They arrived at this number by using only data that included dietary records, excluding people who had any kind of major disease at the start of the study, and eliminating those who reported caloric intake outside of biologically plausible ranges. They also cut anyone who didn’t report on their intake of caffeinated beverages.

Next, using a statistical tool known as a Cox regression model, the researchers equalized the participants based on factors such as age, smoking status, BMI, physical activity, alcohol intake, depression, family history of dementia, medication use and more. This allowed them to focus exclusively on the intake of caffeinated beverages as a protective element in terms of dementia. Basically, it let them ask questions such as: “If two people are the same age, same weight, same smoking status, same blood pressure, similar diet quality — but one drinks more coffee — do we still see a difference in dementia risk?”

They did.

After splitting people into different categories of caffeine intake, and combing medical records for dementia as a cause of death or doctor diagnoses of the condition, they found that those who drank higher amounts of coffee had an 18% lower risk of developing dementia than those who drank the lowest amounts. Those in the highest tea-drinking group had a 14% lower risk, while those who drank the highest amounts of caffeine overall (from either coffee or tea or other caffeinated beverages) had a 22% reduced risk. Decaf coffee consumption was not shown to have any relation to dementia risk.

“This finding suggests that caffeine may be the primary putative neuroprotective agent underlying the observed association,” write the researchers in their study, which has been published in the Journal of the American Medical Association.

Sweet spot

While the words “higher” and “highest” here might sound like people were drinking gallons of caffeinated beverages each day, the researchers actually found that the statistics stated above were found for the consumption of two-to-three cups of coffee per day or one-to-two cups of tea. More than that didn’t provide any additional protections against dementia. The optimal level of caffeine intake for all sources was about 300 mg per day.

While the researchers point out that their study – like all studies of this kind – is observational, not causal, they do offer some reasons why the relationship between caffeine intake and lowered dementia risk might exist.

For one, caffeine has been shown to have positive effects on the brain, because it blocks adenosine receptors, which can increase synaptic signaling and possibly block the production of beta-amyloid, a protein that forms the damaging plaques associated with Alzheimer’s disease. Caffeine may also be involved in lowering cytokines to keep inflammation low and it has been linked to better vascular function, lower risk of type 2 diabetes and improved insulin sensitivity, all of which can improve brain as well as overall health.

There are also other components in caffeinated beverages – particularly tea – that can provide brain boosting effects such as polyphenols and L-theanine which may guard against oxidative stress and support cerebrovascular function.

This research dovetails with other recent studies that have shown that modest daily caffeine consumption can have positive health effects. These include a study showing that each cup of coffee can boost healthy aging by up to five percent; one that shows how caffeine can help boost memory; another that says one cup of coffee per day can protect the heart from atrial fibrillation; and yet another showing that coffee and tea can reduce the risk of head and neck cancers.

Still, moderation seems to be the key as too much caffeine has been linked to sleep disruption, cardiovascular strain, and gastrointestinal issues. Plus, caffeine certainly isn’t a cure-all when it comes to dementia, as senior study author Daniel Wang points out.

“While our results are encouraging, it’s important to remember that the effect size is small and there are lots of important ways to protect cognitive function as we age,” he concludes. “Our study suggests that caffeinated coffee or tea consumption …[for the balance of this very interesting article please visit: https://newatlas.com/health-wellbeing/coffee-tea-dementia-caffeine/]
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Source: Mass General Brigham Communications –

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