Topline
Higher levels of belly and arm fat may increase the risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s, while high muscle strength may decrease this risk, new research suggests, the latest study to explore the link between body composition and brain degeneration.
Key Facts
The study included 412,961 participants between the ages of 40 and 70 who were followed for an average of about nine years; 8,224 participants developed neurodegenerative diseases during this time—mainly Parkinson’s disease, Alzheimer’s disease and other forms of dementia.
The researchers found participants with excess arm fat had an 18% greater risk of developing these diseases compared to participants with low levels of arm fat, according to the study published Wednesday in Neurology, the medical journal of the American Academy of Neurology.
Participants with high levels of belly fat were also 13% more likely to develop these neurodegenerative diseases, and this risk was slightly higher in men than women.
However, there was one factor that consistently decreased risks among participants: Having high muscle strength lowered risks by over 25%.
Previous research found having higher levels of lean muscle mass—the difference between total body weight and body fat—decreases neurodegenerative disease risk, but the Neurology study researchers found inconsistent results on this factor, and suggested muscle quality may play a more important role in reducing risk than muscle quantity.
Crucial Quote
“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,” Dr. Huan Song, a study author and professor for Sichuan University in China, said in a statement.
Why Does Excess Fat Increase The Risk Of Neurodegenerative Disease?
One reason high levels of belly fat increases this risk is due to a type of fat called visceral fat, which only lies around abdominal organs. Visceral fat is also called “hidden fat” because it’s located within the stomach and isn’t visible to the naked eye. Middle-aged people with excess visceral fat have increased levels of tau and amyloid proteins in their brains, which are both indicators of Alzheimer’s, according to a 2023 study published in Aging & Disease. Researchers have found obesity significantly increases the risk of developing neurodegenerative diseases. The brain naturally shrinks with age, but obesity can cause this process to speed up, causing the brain to age by about 10 excess years and increasing Alzheimer’s risk, according to the Alzheimer’s Society. Metabolic changes associated with excess fat can damage the central nervous system, and can then lead to neuronal cell death, which is a known contributor to neurodegenerative disease, a Life Sciences study suggested.
Tangent
The Neurology study researchers also considered how cardiovascular diseases—like heart disease or stroke—factor into degenerative brain disease development. Around 35% and 22% of participants with excess belly and arm fat, respectively, developed some form of cardiovascular disease after the study began, but before the onset of neurodegenerative diseases. Cardiovascular diseases have been previously linked as risk factors for neurodegenerative disease. The researchers believe early management of cardiovascular diseases in people with excess arm and belly fat may mitigate neurodegeneration.
Big Number
30 million. That’s how many people worldwide are living with a degenerative brain disease, according to the Cleveland Clinic.
