Three cups of coffee a day could slow the loss of mental function in men, says a European study.
The results appear in line with a growing body of evidence linking coffee consumption to improved cognitive function, and follow a recent report from Austria that "showed" how caffeine boosts brain function through its effects on distinct areas of the brain.
The Austrian results, presented at the annual meeting of the Radiological Society of North America in December, were said to be the first to demonstrate a visible impact on the brain from caffeine.
The new results, published on-line ahead of print in the European Journal of Clinical Nutrition ( doi: 10.1038/sj.ejcn.1602495), now suggest that older men may also benefit mentally from regular and moderate coffee consumption.
The Finland, Italy, and the Netherlands Elderly (FINE) Study followed 676 healthy men born between 1900 and 1920 for ten years. Daily coffee consumption was estimated in cups per day, and cognitive functioning was measured using the Mini-Mental State Examination. The exam evaluates mental performance on a scale of 0 to 30, with higher scores indicating better performance.
Cognitive performance declines naturally with age, but the results of the FINE study showed that men who had regular consumption of coffee had a lower rate of decline over the ten-year period than men who did not drink coffee (declines of 1.2 versus 2.6 points for drinkers and non-drinkers, respectively).
"An inverse and J-shaped association was observed between the number of cups of coffee consumed and cognitive decline, with the least cognitive decline for three cups of coffee per day (0.6 points)," wrote lead author Boukje van Gelder from the National Institute for Public Health and the Environment, the Netherlands.
"This decline was 4.3 times smaller than the decline of non-consumers," she said.
This finding led the researchers to conclude that consuming coffee regularly could reduce cognitive decline in elderly men.
The study was purely observational and could not identify the mechanism behind these apparent benefits. However, previous studies had shown how caffeine might be enhancing memory, by binding to brain receptors, blocking the calming effect of the adenosine neurotransmitter.
Coffee, one of the world's largest traded commodities produced in more than 60 countries and generating more than $70bn in retail sales a year, continues to spawn research and interest, and has been linked to reduced risks of certain diseases, especially of the liver and diabetes.