Skinny Fat Body Type Linked to Dementia Risk in Study

Being so-called skinny fat could pose a double threat to brain health according to a study into the causes of dementia.

As we age, we naturally lose muscle tissue in a process called sarcopenia. And neurologists believe the combination of low muscle mass and high body fat known as skinny fat, or sarcopenic obesity, could be a predictor of poor brain function in older people.

To investigate this potential link, researchers at Florida Atlantic University’s Comprehensive Center for Brain Health in the Charles E. Schmidt College of Medicine recruited 353 participants with an average age of 69 years old.

The participants completed cognitive tests, as well as physical exercises to measure their grip strength and how easily they could stand up from a chair. The researchers also documented their body fat percentage, muscle mass, body mass index.

The combination of high body fat and low muscle mass, or sarcopenic obesity, appeared to pose the biggest threat to cognitive function and overall health, the researchers found. More specifically, sarcopenic obesity was linked to lower executive function: Skills which help us to perform tasks which involve time management and mental focus.

Those with sarcopenic obesity also performed the worst on cognition tests involving working memory, mental flexibility, self-control and orientation, followed by those who were just sarcopenic, and then those who were obese alone.

The decline of these functions are among the symptoms of Alzheimer's disease, the most common form of dementia. 

The team believes high body fat levels may have worsened the effects of low muscle mass. That could be because of the negative impact obesity can have on an individual's vascular system, metabolism and inflammatory responses in the body. In turn, obesity can occur in people with lower executive function because it is tied to behaviors such as lower impulse control, the authors stated. 

But while these factors have been linked to cognitive decline, the study does not provide definitive proof that being skinny fat causes Alzheimer’s disease, the researchers acknowledged.

Read more: Alzheimer's Markers Linked to High Sugar, High Fat Foods in Study on Mice

Nevertheless, the authors said higher body fat and a drop in muscle mass in older adults should be treated as a serious health concern.

The results were published in the journal Clinical Interventions in Aging.

Dr. James E. Galvin, a senior author of the study and associate dean for clinical research and a professor of integrated medical science in FAU's Schmidt College of Medicine, said in a statement: "Understanding the mechanisms through which this syndrome [sarcopenic obesity] may affect cognition is important as it may inform efforts to prevent cognitive decline in later life by targeting at-risk groups with an imbalance between lean and fat mass.

“They may benefit from programs addressing loss of cognitive function by maintaining and improving strength and preventing obesity."

Dr. Magdalena I. Tolea, a research assistant professor of integrated medical science and co-author of the study, commented: "Sarcopenia either alone or in the presence of obesity, can be used in clinical practice to estimate potential risk of cognitive impairment.

Clinicians could, for instance, test grip strength and measure body mass index as part of a general check-up to monitor their patient's risk of cognitive decline, she said. 

Dr. Doug Brown, chief policy and research officer at the U.K.-based charity Alzheimer’s Society told Newsweek: "This study suggests people struggling with mid-life obesity and muscle loss due to ageing are more likely to experience some impairment to their brain and thinking abilities."

He said while the study provides motivation to keep fit, "we need longer-term investigation to understand whether maintaining muscle and strength in later life can keep our brains healthy and prevent dementia."

An estimated 5.7 million Americans are currently living with Alzheimer’s disease, the most common form of dementia. This figure is expected to rise to 14 million by 2020.

This is the latest study to investigate the link between physical health and cognitive decline. A separate study published in the BMJ suggested moderate to high intensity exercise does not ease the symptoms of dementia.

This article has been updated with comment from Dr. Doug Brown. 

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