Whether You Carry Fat in Your Arms or Legs Could Predict Risk of Dementia
Enhancing your muscles may offer greater brain health benefits than the current craze of weight-focused anti-obesity medications such as Ozempic, researchers of a recent study claim.
According to the retrospective analysis conducted by scientists from Sichuan University in China, grip strength and locations of subcutaneous fat do a better job of predicting neurodegenerative diseases and biological signs of aging in the brain than more general measures of muscle and overall body fat.
"This study highlights the potential to lessen people's risk of developing these diseases by improving their body composition," explains Sichuan University epidemiologist Huan Song.
Led by Sichuan University physician Shishi Xu, the team analyzed nine years' worth of data from 412,691 people who participated in the UK Biobank. With an average age of 56 at the start of the study, 8,224 of them went on to develop dementia including Alzheimer's and Parkinson's diseases.
Participants who maintained relatively high muscle strength as measured by their grip across the study were 26 percent less likely to develop a neurodegenerative condition such as dementia.
"Muscle quality, compared with muscle quantity, might play a more important role in the development of neurodegenerative diseases," the researchers write in their paper.
Their analysis also revealed those with a higher measure of arm fat compared with leg fat were also 18 percent more likely to receive a diagnosis for a neurodegenerative condition.
This of course does not mean arm fat causes these neurodegenerative conditions. What's more, the study participants were mostly of Anglo-Saxon descent so the findings may not hold true in other populations.
But the distribution of fat on our bodies is in the very least a sign of health problems that may exacerbate brain aging. For example, many of the patients who went on to develop a neurodegenerative condition have a history of heart disease and strokes, both of which have been directly linked to excess fat.
Subcutaneous fat can be a sign our bodies have fatty deposits in visceral organs – including our muscles – increasing inflammation and impairing their function. This then leads to damage to the inner linings of blood vessels leading directly to heart disease. Xu and team suspect this same dysfunction of the lining may also be involved in neurodegeneration.
Fat-transporting protein genes have also been implicated in Alzheimer's disease, as have fatty diets in animal studies and western diets in humans, which are notorious for unhealthy weight gain.
However, "the underlying mechanisms linking body composition and neurodegeneration have not been fully investigated," Xu and team explain.
What's more, such severe conditions as stroke and heart disease themselves make it a lot harder for patients to keep up muscle tone and stay on top of weight changes.
"This underscores the importance of managing these cardiovascular diseases right away to help prevent or delay the development of Alzheimer's, Parkinson's, or other degenerative diseases," says Song.
Belly fat was another factor associated with increased risk of neurodegeneration. In men with high levels of fat around their trunk, the disease rate was 3.38 cases per 1,000 person years, compared to 1.83 cases among men with low belly fat levels. In women with high abdominal fat levels, the rate of neurodegenerative disease was 2.55 per 1,000 person years, compared to women with low amounts of belly fat at 1.39.
"Targeted interventions to reduce trunk and arm fat while promoting healthy muscle development may be more effective for protection against these diseases than general weight control," suggests Song.
"These neurodegenerative diseases like Alzheimer's and Parkinson's affect over 60 million people worldwide, and that number is expected to grow as the population ages, so it's crucial that we identify ways to modify risk factors to develop some preventive tools."
This story was published in Neurology.
