In the study, published in Neurology, the medical journal of the American Academy of Neurology, the researchers suggest that extra belly and upper arm fat may increase the risk of these conditions, whereas increased muscle mass could decrease the risk.
Higher risk with both belly and upper arm fat
Researchers analyzed data from 412,691 people, who were followed for an average of nine years. During the study, 8,224 people developed neurodegenerative diseases. The most common diagnosis was Alzheimer’s disease, with some people developing other dementias, or Parkinson’s disease.
At the start of the study, participants had an average age of 56. The researchers assessed body composition by measuring waist and hips, grip strength, bone density, and fat and lean mass.
They found that people with more belly fat (central obesity), or more upper arm fat (arm-dominant fat distribution) had an increased risk of developing neurodegenerative disorders.
Higher bone density and leg-dominant fat distribution decreased the risk, while high muscle strength appeared to protect against neurodegeneration.
These results are in line with previous research, which has suggested that people with central or abdominal obesity are at increased risk of developing dementia.
This study highlights the potential to lessen people’s risk of developing these diseases by improving their body composition. 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.