Heavy coffee drinkers experience faster cognitive decline
A major study presented at the International Conference of the Alzheimer’s Association (AAIC) 2024, held in the United States, examined the link between coffee drinking and cognitive decline. This large-scale study, carried out by researchers in Australia and the United States, reports findings that could affect how daily caffeine intake is viewed, especially for older people.
High coffee intake linked to faster decline
The main result is that drinking more than three cups of coffee a day is associated with a faster drop in cognitive abilities among people aged 60 years and over. Those who drank four or more cups daily were more likely to show accelerated decline in functions such as logical thinking and pattern recognition. High coffee consumption was also associated with faster age-related declines in vocabulary and general knowledge.
The study analysed roughly 8,500 individuals from the UK Biobank, with an average age of 67.8 years, and a sample that was predominantly female (60% female) and white (97% white), all without baseline cognitive impairment. The UK Biobank supplies detailed, anonymised genetic information and health data from a half‑million Britons. Participants self-reported their daily coffee and tea intake (which can introduce recall bias), a limitation noted by the authors.
Tea consumption shows a different picture
Tea showed a different pattern. The study classified tea intake the same way as coffee, with high consumption set at four or more cups per day. Those who drank a lot of tea tended to have better outcomes for “fluid intelligence” (the ability to reason logically and abstractly) than people who did not drink tea. Non‑tea drinkers showed larger deficits in fluid intelligence compared with those who drank four or more cups daily.
Meanwhile, moderate coffee intake (defined as one to three cups a day) appeared to slow the decline in mental abilities. This is consistent with earlier research suggesting moderate coffee consumption may be linked to lower risks of stroke, heart failure, diabetes and neurodegenerative diseases.
Study limitations and caveats
There are several important caveats. Because the study is observational, it cannot prove cause and effect. The self‑reported nature of coffee and tea intake allows for misreporting. The researchers also did not account for midlife caffeine habits or preparation methods (for example, brewing style), and they did not analyse different coffee or tea varieties.
The participant profile, largely female and white, might not reflect the broader population, limiting the generalisability of the findings. The paper also did not give a precise follow‑up length, referring only to “several years”.
Research collaboration and wider relevance
This work was a collaboration between Australian and U.S. scientists, and the results were unveiled at the AAIC 2024 in the United States. Given that in Germany coffee is the favourite drink, averaging four cups per day, these findings could lead people there (and elsewhere) to reconsider daily consumption habits.
The relationship between caffeine intake and cognitive health is complex and appears to depend on amount consumed. The study suggests individuals and health professionals should weigh potential health benefits against possible risks as people age.