Now we know why women spend so much time chatting while having a cup of coffee: caffeine appears to protect thinking skills in older women.

A new research showed that women aged 65 and older who consumed over three cups of coffee (or the same caffeine amount in tea) daily scored better over time on memory tests than women who drank one cup or less of coffee/tea daily.

These findings persisted even after researchers took into account other factors influencing memory skills, such as age, education, disability, depression, high blood pressure, medications, cardiovascular disease, and chronic conditions. "Caffeine is a psychostimulant which appears to reduce cognitive decline in women," said author Dr. Karen Ritchie, of INSERM, the French National Institute for Health and Medical Research, in Montpellier, France.

"While we have some ideas as to how this works biologically, we need to have a better understanding of how caffeine affects the brain before we can start promoting caffeine intake as a way to reduce cognitive decline. But the results are interesting - caffeine use is already widespread and it has fewer side effects than other treatments for cognitive decline, and it requires a relatively small amount for a beneficial effect."

The research was made on a sample of 7,000 subjects whose cognitive abilities and caffeine consumption were monitored over four years. The memory benefits of the caffeine appeared to rise with age - coffee drinkers being 30 % less exposed to memory impairment at age 65 and 70 % less over 80. Still, caffeine consumers were not found to present lower rates of dementia.

"We really need a longer study to look at whether caffeine prevents dementia; it might be that caffeine could slow the dementia process rather than preventing it," said Ritchie.

Why caffeine induces a slightly different effect on women than it does in men is not clearly known. "Women may be more sensitive to the effects of caffeine. Their bodies may react differently to the stimulant, or they may metabolize caffeine differently.", she said.