March 4, 2015

Poor Heart Function Could Be Major Risk for Alzheimer's Disease

NASHVILLE, Tenn -- March 4, 2015 -- A healthier heart could prevent Alzheimer's disease, according to a study published in the online issue of the journal Circulation.

The study associates heart function with the development of dementia and Alzheimer's disease. Participants with decreased heart function, measured by cardiac index, were 2 to 3 times more likely to develop significant memory loss over the follow-up period.

“Heart function could prove to be a major risk factor for dementia and Alzheimer's disease,” said Angela Jefferson, PhD, Vanderbilt University Medical Center, Nashville, Tennessee. “A very encouraging aspect of our findings is that heart health is a modifiable risk. You may not be able to change your genetics or family history, but you can engage in a heart healthy lifestyle through diet and exercise at any point in your lifetime.”

The research used data from the Framingham Heart Study, an effort that began in 1948 to identify risk factors for heart disease. A total of 1,039 participants from Framingham's Offspring Cohort were followed for up to 11 years to compare cardiac index to the development of dementia.

Over the study period, 32 participants developed dementia, including 26 cases of Alzheimer's disease. Compared with normal cardiac index, individuals with clinically low cardiac index had a higher relative risk of dementia.

“We thought heart disease might be driving the increased risk of dementia and Alzheimer's disease,” said Dr. Jefferson. “When we excluded participants with heart disease and other heart conditions, we were surprised that the risk of dementia and Alzheimer's disease got even worse.”

She said the research community has long associated heart health with brain health, but cardiac index has not been previously recognised as a risk factor for significant memory loss or dementia.

“For the average adult, the brain accounts for 2% of overall body weight but receives as much as 15% of blood leaving the heart,” said Dr. Jefferson. “If there are changes in the heart's ability to pump blood, the brain is resilient and does a great job at regulating blood flow to maintain a consistent level to support brain tissue and activity. But as we age, our vessels tend to be less healthy. They become less adaptable to blood flow changes, and those changes may affect brain health and function.”

“The risk we found between lower cardiac index and the development of dementia may reflect a subtle but protracted process that occurs over decades -- essentially a lifetime burden of subtle reductions in oxygen and nutrient delivery to the brain,” she added. “That possibility is concerning given the observation that 1 in 3 participants in our study met the medical definition for low cardiac index.”

SOURCE: Vanderbilt University Medical Center
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