Coffee, Tea, or……

By Peter Galvin, MD

Alzheimer disease (AD), the most common cause of dementia, currently affects more than 6 million people in the U.S. and is projected to nearly double to 13 million by 2050. The clinical trajectory of dementia is considered as a continuum that may begin with subjective cognitive decline (a stage where individuals perceive their own cognitive changes), progressing to mild cognitive impairment with measurable deficits on objective cognitive testing, and ultimately to cognitive impairment. With limited treatment options and potential adverse effects of available therapies, early prevention is crucial. Among modifiable risk factors, dietary components have garnered increasing attention. Coffee contains bioactive compounds, including caffeine and polyphenols, which may offer neuroprotection by reducing oxidative stress and neuroinflammation.

Some studies have suggested that chronic caffeine exposure may influence AD-related processes, including the buildup of amyloid and tau proteins. Plus, caffeine has been linked to improved insulin sensitivity and vascular function, which may help protect against cognitive decline. But study findings have been inconsistent until a landmark study from Harvard Medical School was published in March (on St. Patrick’s Day, actually) in the Journal of the American Medical Association, or JAMA. The study’s authors used data from the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS) that had up to 43 years of follow-up with repeated dietary measurements and assessments of dementia, subjective cognitive decline, and objective cognitive function. They hypothesized that higher consumption of caffeinated coffee, tea, and caffeine was associated with lower dementia risk and better cognitive function.

The NHS was begun in 1976 and enrolled 121,700 female registered nurses aged 30 to 55 years. The HPFS started in 1986 and recruited 51,529 male health professionals aged 40 to 75 years. Questionnaires were sent biennially to collect information on lifestyle factors and health conditions. Specific information on dietary intake was included, such as how often specific foods and beverages were consumed including portion sizes. Caffeine intake was derived from intake levels of coffee, tea, soda, and chocolate. Primary exposures were caffeinated coffee, decaffeinated coffee, and tea intake. In addition, total caffeine intake was analyzed as secondary exposure. Dementia was the primary outcome. Cases of dementia were identified through death records, self-reported information, next-of-kin confirmation, medical records, and autopsy reports.

The authors found that higher intake levels for caffeinated coffee, tea, and caffeine were associated with a significantly reduced risk of dementia. The actual dementia risk reduction was 10%. Notably, the strongest association with dementia risk reduction was observed at moderate levels of consumption. There was no additional advantage at higher levels of consumption. There was no risk reduction observed in those who consumed decaffeinated beverages. The findings of this study are consistent with prior studies that showed an inverse relationship between caffeine consumption and AD. Prior studies have also found that moderate coffee consumption is associated with a reduction in the risk of cardiovascular disease.

It should be noted that caffeine can have some negative side effects, for example sleep disruption and heart rhythm disturbances. If you are not a coffee/tea/caffeine user, it would be a good idea to check with your healthcare provider before beginning regular caffeine consumption.

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