For women older than 65, drinking that extra cup of joe may protect thinking and memory skills, according to a new study published Monday in the journal Neurology.
Women who drank more than three cups of coffee -- or the equivalent amount of tea -- per day showed less decline in performance over time on memory tests than women who drank only one cup or less of coffee.
"We looked at the relationship between coffee drinking and cognitive decline, and we found that there was a relationship," said Karen Ritchie, an epidemiological and clinical researcher at La Colombiere Hospital in Montpellier, France.
"It was clear -- the more coffee, the less the decline. We then had to adjust for other factors, and we found that the more we adjusted, the greater the effect."
The study observed 7,000 people over age 65 whose memory skills and caffeine consumption were monitored for four years.
Since most people get their daily dose of caffeine in a cup (or three) of coffee, the number of times participants enjoyed this beverage daily was used as a measure of how much caffeine they took in daily -- though the chemical also exists in tea, soda, chocolate and other foods in smaller amounts.
The researchers found that not only did heavy coffee-drinkers have less memory decline, but the benefits increased with age. Women over the age of 80 who drank four or more cups of coffee were 70 percent less likely to have a decline in memory. However, consuming caffeine did not seem to reduce rates of dementia.
The benefits of increased coffee intake are significant for women, but caffeine's mind-preserving effects were not seen in men, causing researchers to wonder why.
"It could be something about the difference in sex hormones and coffee, or it could be that women metabolize caffeine differently," said Ritchie, who considers herself a modest tea drinker.
"We do know that men and women do metabolize caffeine differently," she said, adding that they also metabolize alcohol and other substances in different ways.
The researchers said that although they are not sure exactly how caffeine, a stimulant, seems to decrease memory loss, they think it may put the brakes on the chemical changes in the brain that are thought to eventually lead to Alzheimer's disease.
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Ritchie is quick to point out that drinking more than three cups of coffee per day isn't recommended for everyone, including people who have high blood pressure.
"Please don't run out and drink coffee if you're not used to it," she said, citing the possible problems that can arise with a dose of caffeine, including increased blood pressure, insomnia, irritability and a racing heartbeat.
Other experts agree that the research is encouraging, though preliminary.
"This is a good study, but one thing did concern me: It is assumed that caffeine is the operative compound here," said Keith Ayoob, associate professor in the department of pediatrics at Albert Einstein College of Medicine in New York.
"The authors said that women were greater consumers of tea -- very high in antioxidants -- but that there was no difference in effect between coffee and tea," he said. "Fine, but coffee is also loaded with antioxidants -- some different ones, but antioxidants nonetheless."
In addition to the question of antioxidants, some researchers believe there may have been some problems in the design of the study.
"There are questions about the dosage, because some people would make stronger coffee than others, so the amount of caffeine can vary per cup," said Zaven Khachaturian, editor in chief of the journal Alzheimer's & Dementia: Journal of the Alzheimer's Association.
He added, "In order to really get a handle on the effectiveness of this for treatment, one needs to have a much larger number of people in the trial."
Study author Ritchie agrees that this is just the beginning. She envisions a future where older women may use a caffeine patch to preserve their minds, but says that a lot of research needs to be done before that time.
"This study opens the door for biologists to look at this question," she said. "To reduce cognitive decline, caffeine is one of the many things we are looking at."