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Hot cocoa may benefit memory, but blood glucose an issue, too

August 9, 2013
by Lois A. Bowers, Senior Editor
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Therapy adherence may not be an issue if the prescription is two cups of hot chocolate a day. In what may be touted as the sweetest dementia-related news in recent memory, researchers have found that following such a course of action may help seniors keep their brains healthy and their thinking skills sharp. Additional investigation is needed before dietary changes are put into place, however, especially because other new research ties a higher risk of dementia to higher blood glucose levels.

In the hot cocoa study, investigators in Boston studied 60 people, aged an average of 73 years, who did not have dementia. The seniors drank two cups of hot cocoa every day for 30 days and did not consume any other chocolate during the study.

As they took memory and thinking tests, blood flow to their brains was measured via ultrasound. Blood flow affects thinking skills, explained study author Farzaneh A. Sorond, MD, PhD, of Harvard Medical School and Brigham and Women’s Hospital in Boston.

“As different areas of the brain need more energy to complete their tasks, they also need greater blood flow,” she said. “This relationship, called neurovascular coupling, may play an important role in diseases such as Alzheimer’s.”

Blood flow was impaired in 18 of the 60 participants at the beginning of the study, but it improved by 8.3 percent by the end of the study. Those whose blood flow was impaired also improved their times on a test of working memory; their scores dropped from 167 seconds at the start of the study to 116 seconds at completion.

Seniors who started the study with regular blood flow saw no improvement in blood flow or in test completion time.

The study results were published this week by the journal Neurology. The research was supported by the National Institute on Aging and the National Heart, Lung, and Blood Institute. The cocoa was provided by Mars Inc. Additional affiliations of investigators include the Veterans Affairs (VA) Boston Healthcare System and Massachusetts General Hospital.

“More work is needed to prove a link between cocoa, blood flow problems and cognitive decline, but this is an important first step that could guide future studies,” said Paul B. Rosenberg, MD, of the Johns Hopkins School of Medicine in Baltimore, who with Can Ozan Tan, PhD, of Harvard Medical School and Spaulding Rehabilitation Hospital in Boston wrote an editorial accompanying the study.

Results of the Boston study were released on the same day as findings from a joint Group HealthUniversity of Washington (UW) study, published in the New England Journal of Medicine, that higher blood glucose levels are associated with higher dementia risk, even among people who do not have diabetes. The Seattle study examined data from more than 2,000 Group Health people aged at least 65 years and participating in the Adult Changes in Thought (ACT) study.

“The most interesting finding was that every incrementally higher glucose level was associated with a higher risk of dementia in people who did not have diabetes,” said first author Paul K. Crane, MD, MPH, an associate professor at the UW School of Medicine and an affiliate investigator at the Group Health Research Institute. “There was no threshold value for lower glucose values where risk leveled off.”

Given the results of this study, should people try to eat less sugar or foods with a lower glycemic index? Not necessarily, Crane said. The body turns food into glucose, and blood glucose levels depend on metabolism as well as what a person eats.

“We have no data to suggest that people who make changes to lower their glucose improve their dementia risk,” Crane added. “Those data would have to come from future studies with different study designs.”

The ACT study previously linked physical activity to later onset and reduced risk of dementia, including Alzheimer’s disease, so perhaps a walk is in order, he said.

The latter study also received support from the National Institute on Aging. Additional researchers were affiliated with the VA Puget Sound Health Care System, the Swedish Neuroscience Institute, Massachusetts General Hospital, Harvard Medical School, the Harvard School of Public Health and Wake Forest School of Medicine.

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