Tea and coffee linked to lower dementia risk in new study

Those who drink caffeinated versions of the popular hot drinks also have better mental skills than those who abstain from them, the research found.

During the large study, experts were able to pinpoint the number of cups of caffeinated drinks each day, which is linked to the reduced risk of developing the illness.

Experts from Harvard University in the US examined data on 131,000 health workers, who were tracked for an average of 43 years.

This included 86,000 female NHS nurses and 45 men working as health professionals in the US.

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Questionnaires about their diet were completed every two to four years, including questions about caffeinated coffee, decaffeinated coffee and tea consumption.

Cognitive tests were also performed.

During the follow-up period, 11,033 cases of dementia were identified.

Analysis suggested that higher caffeinated coffee intake was significantly associated with lower dementia risk - those who drank the highest amount of coffee compared to the lowest appeared to have an 18 per cent lower risk of dementia.

People who drank the most tea appeared to have a 16 per cent reduced ris of developing the brain disease.

Those who consumed the most tea and coffee also showed a slower rate of cognitive decline compared to those who drank the least.

Among the NHS nurses, higher caffeinated coffee consumption was also associated with better objective cognitive performance.

Higher intake of tea showed similar associations, researchers found.

But drinking decaffeinated coffee was not associated with lower dementia risk or better cognitive performance.

Overall, the authors found that the most "pronounced association" was among people who drank a "moderate" amount of tea or coffee, with "no additional advantages" among people who consumed more.

They estimated that consumption of around two to three cups of caffeinated coffee each day, or one to two cups of tea per day, were linked with the lowest risk of dementia compared to people who did not drink these drinks.

"Greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels," they wrote in Jama.

Lead author, Yu Zhang from the TH Chan School of Public Health at Harvard University, said: "Dementia is one of the most important and challenging public health problems worldwide, and there are still very limited effective treatments.

"So identifying modifiable lifestyle factors that may be linked to dementia risk is critical.

"Coffee and tea are widely consumed globally, so even modest associations could have meaningful population-level implications.

"We analysed data from more than 130,000 women and men followed for up to 43 years, with repeated dietary assessments over time.

"We found that higher intake of caffeinated coffee and tea was associated with a lower risk of dementia and better cognitive performance.

"We observed the most favourable associations were at moderate intake levels - the strongest associations were seen at about two to three cups per day of caffeinated coffee and about one to two cups per day of tea.

"We didn't observe additional benefits at higher intake levels."

Commenting on the study, Dr Susan Kohlhaas, executive director of research at Alzheimer's Research UK, said: "This research doesn't prove that coffee or tea protect the brain.

"This study shows an association, not a cause-and-effect relationship.

"People who drink coffee or tea may also differ in other ways that affect brain health, even after careful adjustment, and the study relied partly on self-reported diagnoses.

"It was also conducted in relatively similar groups of health professionals, which limits how widely the results can be applied."