Among a group of older women, self-reported caffeine consumption of more than 261 mg per day was associated with a 36 percent reduction in the risk of incident dementia over 10 years of follow-up. This level is equivalent to two to three 8-oz cups of coffee per day, five to six 8-oz cups of black tea, or seven to eight 12-ounce cans of cola.

"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 very few contraindications," said Ira Driscoll, PhD, the study's lead author and a professor of psychology at the University of Wisconsin-Milwaukee. "What is unique about this study is that we had an unprecedented opportunity to examine the relationships between caffeine intake and dementia incidence in a large and well-defined, prospectively-studied cohort of women."

The findings come from participants in the Women's Health Initiative Memory Study, which is funded by the National Heart, Lung, and Blood Institute. Driscoll and her research colleagues used data from 6,467 community-dwelling, postmenopausal women aged 65 and older who reported some level of caffeine consumption. Intake was estimated from questions about coffee, tea, and cola beverage intake, 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 above the median amount of caffeine for this group (with an average intake of 261 mg per day) were diagnosed at a lower rate than those who fell below the median (with an average intake of 64 mg per day). 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 consumption.

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The paper "Relationships Between Caffeine Intake and Risk for Probable Dementia or Global Cognitive Impairment: The Women's Health Initiative Memory Study" is available at: http://biomedgerontology. oxfordjournals. org/ content/ early/ 2016/ 09/ 20/ gerona. glw078

Direct correspondence to:

Ira Driscoll, PhD

Department of Psychology, University of Wisconsin-Milwaukee

224 Garland Hall, 2441 East

Hartford Avenue, Milwaukee, WI 53211

Email: driscoli@uwm.edu

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