This Daily Habit Could Lower Dementia Risk By 35%, Research Reveals
A new long-term US study has suggested that moderate consumption of caffeinated coffee and tea could help reduce the risk of dementia later in life, adding to growing evidence linking diet and brain health in older adults.
Researchers tracked the health and lifestyle habits of more than 131,000 nurses and healthcare professionals over a period spanning four decades. Participants were initially in their early 40s when the study began, and during the follow-up period around 11,000 individuals went on to develop dementia.
The findings indicated that adults who regularly consumed moderate amounts of caffeine were less likely to develop dementia compared with those who consumed little or none.
According to the researchers, the greatest apparent benefit was seen among adults aged 75 and under. Daily caffeine intake of around 250mg to 300mg — broadly equivalent to two or three cups of coffee — was associated with a significantly lower risk of dementia. However, higher levels of caffeine intake did not appear to provide any additional benefit.
The study also examined tea consumption, with one to two cups per day linked to the strongest protective effect. Researchers noted that tea consumption in the United States is generally lower than coffee consumption, which may have influenced the findings.
Scientists believe caffeine may support brain health through several biological mechanisms. Caffeine is known to block adenosine, a chemical in the brain that slows nerve cell activity. By doing so, it may help maintain the function of neurotransmitters such as dopamine and acetylcholine, both of which are associated with memory and cognitive performance and are known to decline with age.
Researchers also suggested that caffeine could help reduce inflammation and support healthy blood sugar regulation, both considered important factors in maintaining cognitive health. Coffee and tea also contain antioxidants and compounds that may help protect blood vessels and support healthy brain function.
The study highlighted that lifelong coffee drinkers without dementia were found in some previous research to have lower levels of amyloid plaque build-up in the brain — one of the hallmarks associated with Alzheimer’s disease.
However, the researchers stressed that moderation appears to be key. Very high caffeine intake may interfere with sleep quality and increase anxiety, both of which can negatively affect cognitive wellbeing. Experts say this supports longstanding theories suggesting that mental performance improves only up to an optimal level of stimulation, after which excessive stimulation may become counterproductive.
An unexpected finding involved decaffeinated coffee. Participants who consumed higher amounts of decaf appeared to experience faster memory decline. Researchers cautioned against drawing direct conclusions, suggesting that some individuals may have switched to decaffeinated drinks because of pre-existing health concerns such as sleep disorders, high blood pressure or heart rhythm problems — all conditions linked with increased dementia risk.
The researchers also pointed out that measuring caffeine intake is not straightforward, as caffeine content can vary considerably depending on brewing methods and drink preparation.
Health experts continue to advise balance, particularly for older adults and those with cardiovascular conditions. While moderate caffeine intake is generally considered safe for most people, individuals with high blood pressure are often advised to limit coffee consumption.
The findings contribute to a growing body of research suggesting that simple lifestyle factors — including diet, exercise, sleep and social engagement — may all play an important role in supporting healthy ageing and reducing dementia risk.
