New research by scientists in France and Portugal suggests that drinking caffeine may help protect thinking and memory skills in older women.

The study is published in Neurology, the journal of the American Academy of Neurology (AAN).

Study author Dr Karen Ritchie, of INSERM, the French National Institute for Health and Medical Research, in Montpellier, France, said:

"Caffeine is a psychostimulant which appears to reduce cognitive decline in women."

Using tests of memory and thinking skills, Ritchie and colleagues showed that cognitive decline was slower in women aged 65 and over who drank more than three cups of caffeinated coffee or tea a day compared with women who drank one cup or less.

The results were unaffected by potential confounding factors such as age, education, disability, depression, medication, hypertension (high blood pressure), cardiovascular disease and other chronic conditions.

However, until more is discovered about how and why this is so, the authors are not suggesting older women should start drinking more coffee, as Ritchie explained:

"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 nonetheless interesting she said, because:

"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."

However, caffeine did not appear to modify the risk of dementia over the four years of the study:

"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," explained Ritchie.

Also, caffeine appeared to have no effect on slowing cognitive decline in men. Ritchie suggested this could be because:

"Women may be more sensitive to the effects of caffeine. Their bodies may react differently to the stimulant, or they may metabolize caffeine differently."

The researchers studied the cognitive decline, incident dementia and caffeine intake of 4,197 women and 2,820 men aged 65 and over living in three French cities over four years. They tested the participants' cognitive skills at the start of the study and then at years 2 and 4.

The results showed that:

* Compared to women who drank only one cup a day or less, women who drank 3 or more cups of coffee or tea a day had a 33 per cent reduced risk of decline in verbal retrieval over four years (odds ratio 0.67).
* They also showed a reduced risk of decline in visuospatial memory, but this was smaller (odds ratio 0.82).
* The protective effect of caffeine appeared to increase with age, rising from a 27 per cent reduced risk of cognitive decline for women aged 65 to 74, to 70 per cent for women aged 80 and over (odds ratios were 0.73, and 0.3 respectively).
* No link between caffeine intake and cognitive decline was found in men.
* Incidence of dementia appeared to be unaffected by caffeine consumption over the four years of the study.

The authors concluded that:

"The psychostimulant properties of caffeine appear to reduce cognitive decline in women without dementia, especially at higher ages."

Although their results showed no impact on incidence of dementia, they suggested that:

"Although no impact is observed on dementia incidence, further studies are required to ascertain whether caffeine may nonetheless be of potential use in prolonging the period of mild cognitive impairment in women prior to a diagnosis of dementia."

"The neuroprotective effects of caffeine: A prospective population study (the Three City Study)."
K. Ritchie, I. Carriere, A. de Mendonca, F. Portet, J. F. Dartigues, O. Rouaud, P. Barberger-Gateau, and M. L. Ancelin.
Neurology 2007 69: 536-545.
August 7 2007, Volume 69, Issue 6.