Drinking more than three cups of coffee a day helped protect older women against some memory decline, according to a study from researchers in France. But men did not enjoy the same benefit.

The study, published in the journal Neurology, found that women age 65 and older who drank more than three cups of coffee per day -- or the equivalent in tea -- showed less decline over time on tests of memory than women who drank one cup or less of coffee or tea per day.

The results held up even after researchers adjusted for other factors that could affect memory abilities, such as age, disability, depression, education, high blood pressure, medications, cardiovascular disease, and other chronic illnesses.

The researchers led by Karen Ritchie, of the French National Institute for Health and Medical Research, followed more than 7,000 men and women in three French cities.

The team checked their health and mental function and asked the women about their current and past eating and drinking habits.

They found that, compared to women who drank one cup or fewer per day, women who drank lots of coffee had:

  • 33 per cent lower odds of having verbal memory declines
  • 18 per cent lower odds of having visual and spatial memory declines.

Women over 80 reaped more benefits from these beverages than those who were 10 to 15 years younger. It was unclear whether current or former coffee consumption made the difference.

Ritchie is not sure why only women benefited in her study, but noted their bodies may react differently to caffeine, or they may metabolize caffeine differently.

Some studies in mice have suggested that caffeine might block the buildup of proteins that lead to mental decline. Ritchie says researchers need to better understand how caffeine affects the brain before intake can be promoted 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," she says.