MONDAY, Aug. 6, 2007 (HealthDay News) -- Coffee may jolt more than just the nervous system. A new French study found that caffeine seemed to help preserve the cognitive skills of older women.
Women who drank three or more cups of coffee a day were 30 percent less likely to have memory decline at age 65 than whose who drank one cup or less daily.
And the benefit increased with age. Women over age 80 who drank three or more cups of coffee a day were about 70 percent less likely to have memory decline than those who drank one cup or less, the researchers said.
Caffeinated tea had the same effect in the women, the study found, although more was needed to get the same caffeine boost. "Count roughly two cups of tea for a cup of coffee," said study leader Karen Ritchie of INSERM, the French National Institute for Health and Medical Research.
But the researchers didn't find a similarly protective effect in men, although other studies have found a benefit to males.
How might caffeine help ward off cognitive decline? "It is a cognitive stimulant," said Ritchie. It also helps to reduce levels of the protein called beta amyloid in the brain, she said, "whose accumulation is responsible for Alzheimer's disease but which also occurs in normal aging."
Ritchie said she wasn't sure why men in the study didn't benefit from caffeine. "Our hypothesis is that either women metabolize caffeine differently than men, or there may be an interaction [of the caffeine] with the sex hormones, the estrogen-progesterone balance," she said.
Ritchie and her colleagues recruited more than 7,000 women and men from three French cities. All were dementia-free at the start of the study. The researchers evaluated cognitive performance with a series of tests, such as verbal recall, asking people to demonstrate how many words they could repeat back after hearing them in 30 seconds. The evaluations were done at the start of the study and then two and four years later.
The researchers also asked about caffeine consumption at each evaluation.
Ritchie's team did not find that caffeine reduced the rate of dementia that developed within the four-year follow-up period. But the follow-up may not have been long enough to determine for sure if caffeine protected not just thinking skills but helped to ward off dementia. More research is needed to find out if caffeine may actually prolong the period of mild cognitive impairment in women before they receive a diagnosis of dementia, she said.
The study results are published in the Aug. 7 issue of the journal Neurology.
The French study confirms previous research, said William Scott, professor of medicine at the University of Miami Miller School of Medicine, who has researched caffeine's beneficial effects against Parkinson's disease, also a neurodegenerative disorder.
The Ritchie research "is another piece of the puzzle," Scott said. "The next step is to figure out what that mechanism is."
As for caffeine only protecting women, Scott noted that just 2,800 of the 7,000 study participants were men, and the results might have differed if more men were included.
A study published in February in the European Journal of Clinical Nutrition looked at 676 healthy men and found that regular coffee drinkers had a lower rate of cognitive decline over a 10-year follow-up than those who didn't drink coffee. Those who drank three cups daily had the least signs of decline.
Both Scott and Ritchie agreed that more study is needed. Ritchie's research will next look at the relationship between caffeine and Alzheimer's.
Meanwhile, Scott concluded: "What I would say to people over 65 is that there seems to be a consistent, inverse association between caffeine consumption and some of these neurodegenerative diseases." Unless a physician advised against it, he added, daily coffee drinking "doesn't seem to hurt."
More information
To learn about coffee and health, visit Harvard Medical School.
