Burning More Calories Boosts Brain Volume

Megan Brooks

March 30, 2016

For elderly adults, increasing the amount of calories burned each week from a variety of physical activities can increase brain volume and cut the risk for Alzheimer's disease (AD), regardless of their cognitive status, a new study suggests.

Multiple studies have shown that physical activity can be neuroprotective and reduce the risk for AD. But knowing that it is energy expenditure that is primarily associated with exercise- induced brain changes "adds substantial value to existing epidemiologic studies that address the role of increased physical activity in delaying the clinical manifestation of AD," the investigators, led by Cyrus Raji, MD, PhD, University of California, Los Angeles, write.

The study was published online March 11 in the Journal of Alzheimer's Disease.

More Is Better

The investigators analyzed data obtained over 5 years from 876 adults aged 65 years and older in the long-running Cardiovascular Health Study. Participants underwent periodic standard cognitive assessment and volumetric magnetic resonance brain imaging and provided information on their everyday physical activities, such as walking, tennis, dancing, and golfing, to determine their weekly energy output.

Dr Cyrus Raji

Using mathematical modeling and after accounting for potentially confounding factors, such as head size, age, and cognitive status, higher energy expenditure from a variety of physical activities was associated with larger gray matter volume in frontal, temporal, and parietal lobes, as well as the hippocampus, thalamus, and basal ganglia, the researchers found.

"High levels of caloric expenditure also moderated the neurodegeneration-associated volume loss in the precuneus, posterior cingulate, and cerebellar vermis," they report.

This study adds to the literature on exercise and the brain "by linking increased gray matter with a twofold risk reduction of Alzheimer's dementia 5 years after the time of the magnetic resonance imaging scan," Dr Raji told Medscape Medical News.

And when it comes to energy expenditure, "more is better."

"The highest quartile group of physical activity (500 calories from leisure physical activities) had larger gray matter volumes and reduced atrophy in Alzheimer's dementia than the lowest quartile (only 50 calories from physical activity)," Dr Raji said.

"With the elderly population growing rapidly, a better understanding of preventive measures for maintaining cognitive function is crucial," the researchers note.

"Studies such as this one suggest that simply caloric expenditure, regardless of type or duration of exercise, may alone moderate neurodegeneration and even increase gray matter volume in structures of the brain central to cognitive functioning.

"Future studies examining the preservation of brain matter as a function of physical activity will help elucidate whether the association between caloric expenditure and gray matter volume is a direct or indirect relationship. Such knowledge can give individuals the tools to better impact their brain health throughout the aging process," the investigators conclude.

Amyloid Fighter?

Reached for comment, Majid Fotuhi, MD, PhD, chief medical officer, Neurocore Brain Performance Center, and affiliate staff, Johns Hopkins Medicine, Baltimore, Maryland, noted that "exercise grows the size of the hippocampus by increasing the level of the protective protein brain-derived neurotrophic factor (BDNF) in a dose-dependent fashion and by enhancing oxygen supply for neurons. When you become physically fit, you grow the size of your hippocampus and you lower the chance of developing Alzheimer's disease decades later.

"It is time that we reconsider how we label cognitive decline with aging. Dr Raji's study provides yet another strong evidence on how we can fight late-life dementia by exercising more and enhancing our stamina, regardless of how much amyloid we harbor in our brains. In fact, exercise may turn out to be an effective way to combat amyloid accumulation in our brains," Dr Fotuhi added.

The study was funded by the National Institute on Aging. Dr Raji has received consulting fees from Brainreader ApS and the Change Your Brain Change Your Life Foundation. Dr Fotuhi reports no relevant financial relationships.

J Alzheimers Dis. Published online March 11, 2016. Full text


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