A new study suggests a significant relationship between caffeine and dementia prevention, although it stops short of establishing cause and effect.

The study, published in the Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, found that higher caffeine intake in women 65 and older was associated with reduced odds of developing dementia or cognitive impairment.

Among the women in the study, self-reported consumption of more than 261 milligrams of caffeine per day was associated with a 36 percent reduction in the risk of dementia over 10 years of follow-up. That level is equivalent to two to three eight-ounce cups of coffee, five to six eight-ounce cups of black tea or seven to eight 12-ounce cans of cola.

“While we can’t make a direct link between higher caffeine consumption and lower incidence of cognitive impairment and dementia, with further study we can better quantify its relationship with cognitive-health outcomes,” said Ira Driscoll, the study’s lead author and a professor of psychology at the University of Wisconsin at Milwaukee.

“The mounting evidence of caffeine consumption as a potentially protective factor against cognitive impairment is exciting given that caffeine is also an easily modifiable dietary factor” with few risk factors, Driscoll said.

The study was unique because researchers had an unprecedented opportunity to examine over time the relationship between caffeine intake and dementia incidence in a large group of women who consumed different amounts of caffeine, according to Driscoll.

The findings come from participants in the Women’s Health Initiative Memory Study, which was funded by the National Heart, Lung, and Blood Institute. Driscoll and her research colleagues used data from 6,467 post-menopausal women who reported some level of caffeine consumption. Intake was estimated from questions about intake of coffee, tea and cola, including frequency and serving size.

In 10 years or less of follow-up with annual assessments of cognitive function, 388 of these women received a diagnosis of probable dementia or some form of global cognitive impairment.

Those who consumed more than the median amount of caffeine for this group were diagnosed at a lower rate than those who fell below the median. The researchers adjusted for risk factors such as hormone therapy, age, race, education, body mass index, sleep quality, depression, hypertension, prior cardiovascular disease, diabetes, smoking and alcohol use.