Study Suggests Excess Arm and Stomach Fat Increases Risk of Alzheimer's and Parkinson's

According to a study published in the journal Life Sciences, 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.

In the study, researchers recruited 412,961 participants between the ages of 40 and 70 who were followed for an average of about nine years and found that 8,224 participants developed neurodegenerative diseases during this time—mainly Parkinson’s disease, Alzheimer’s disease, and other forms of dementia.

The results revealed that participants with excess arm fat had an 18% greater risk of developing these diseases compared to participants with low levels of arm fat.

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.

One reason high levels of belly fat increase 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.

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 suggested early management of cardiovascular diseases in people with excess arm and belly fat may mitigate neurodegeneration.

Reference: Janaína Niero Mazon, Aline Haas de Mello, Gabriela Kozuchovski Ferreira, Gislaine Tezza Rezin; The impact of obesity on neurodegenerative diseases; Life Sciences; Volume 182; 2017; https://doi.org/10.1016/j.lfs.2017.06.002.