A study tracked more than 131,000 people for up to 43 years.
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A daily cup of coffee or tea may do more than wake you up—it could also help keep your brain sharp as you age.
New research tracking hundreds of thousands of people over decades suggests that moderate caffeine consumption is linked to a lower risk of developing dementia.
“Caffeine increases the brain’s activity and can accelerate the speed of messages between the brain and the body,” Jolene Knight, psychiatric nurse practitioner at Stony Brook Medicine’s Center of Excellence for Alzheimer’s disease, and not involved in the study, told The Epoch Times.
Caffeine Linked to 20 Percent Risk Reduction
The study, recently published in JAMA, followed 131,821 people for up to 43 years and found that those who drank two to three cups of caffeinated coffee or one to two cups of tea daily had a lower risk of developing dementia than those who drank little or no caffeine.
“When searching for possible dementia prevention tools, we thought something as prevalent as coffee may be a promising dietary intervention,” senior author Dr. Daniel Wang, associate scientist with the Channing Division of Network Medicine at Mass General Brigham, said in a statement.
Wang and his team tracked participants from two long-term studies of medical professionals, the Nurses’ Health Study and Health Professionals Follow-Up Study, with starting ages typically in their mid-40s to early 50s.
They found that people who drank between one and five eight-ounce cups of caffeinated coffee had an 18 percent reduced risk of dementia. However, those who drank caffeinated tea daily had a roughly 15 percent reduced risk.
Interestingly, the benefits plateaued beyond two and a half cups of coffee daily, possibly because the body cannot process higher amounts of the beneficial compounds in these beverages. Caffeine can mimic adenosine and bind to receptors in the brain, blocking the molecule that promotes sleepiness, and keeping us alert, Knight said. By doing so, it increases neuron activity, which may reduce inflammation.
“Inflammation is being studied as a cause of cognitive impairment,” she said. “Caffeine has the potential to reduce oxidative stress and neuroinflammation, which helps to decrease brain aging.”
Scientists propose that caffeine might protect the brain by reducing inflammation and improving blood vessel function. It may also enhance insulin sensitivity, which is important because diabetes is a risk factor for dementia, due to the increased risk of heart disease and stroke.
Higher Caffeine, Better Outcomes
During the study, 11,033 participants developed dementia, confirmed through medical records or death certificates. The findings held regardless of genetic risk factors for Alzheimer’s or other dementias.
The study also looked at subjective cognitive decline—people’s perceptions that their memory and thinking skills are slipping. Those who drank more caffeine were less likely to report such issues. Among women over 70, those who drank more caffeine scored better on cognitive tests, indicating slower cognitive decline by about seven months.
Cognitive decline was assessed using cohort-specific questionnaires with yes-or-no responses covering general memory, executive function, attention, and visuospatial skills.
The better cognition among tea and coffee drinkers may come from caffeine’s ability to increase dopamine and acetylcholine in the brain, which are important for memory and cognition, Knight said. “Dopamine is the reward center in the brain and leads to feeling alert, focused, and pleasure. Acetylcholine is the memory neurotransmitter.”
The study didn’t track whether participants added milk or sugar, which could influence health effects. Some experts note that drinking more than four cups a day offers no additional benefits and could even be harmful, potentially disrupting sleep or increasing anxiety.
Researchers caution that they cannot determine causation and that other factors may influence the results. For example, some participants might have been drinking decaffeinated coffee for health reasons, which could affect outcomes.
“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. Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle,” Wang stated.
Moderation Is Key
There are risks associated with increasing caffeine intake, especially for older adults or those with certain health conditions, Knight noted.
Coffee acts as a diuretic, which can lead to dehydration—a concern given that most adults already fall short of the recommended eight glasses of water a day.
“I always tell my patients for each cup of coffee you should drink a glass of water.” She added that dehydration can lead to altered mental status, confusion, and kidney damage.
Finally, Knight cautioned that older people should be careful about caffeine intake, because it can disrupt sleep, which itself is a risk factor for cognitive decline.
“Caffeine can lead to increased difficulty with sleep,” she said. “Poor sleep can impair cognition, causing increased confusion or brain fog, and increase dementia risk over time.”