Greater belly and arm fat raises risk of Parkinson’s, related diseases
Large study of adults in UK supports body composition as affecting health
A person’s body composition, like the ratio of fat to muscle mass, could influence their risk of neurodegenerative diseases such as Parkinson’s and Alzheimer’s, according to a large database study in the U.K.
Among the more than 400,000 middle-aged adults followed for years, higher levels of abdominal and arm fat were associated with an increased risk of developing a neurodegenerative disease, whereas greater muscle strength associated with a lower risk.
“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,” Huan Song, MD, PhD, of Sichuan University in China and the study’s senior author, said in an American Academy of Neurology press release.
“Lifestyle modifications, such as engaging in resistance training, reducing sedentary behavior, and adhering to a balanced diet, can effectively help in reducing central fat and enhancing muscle strength, which may potentially offer greater neuroprotective benefits than weight-focused antiobesity medications,” the researchers wrote.
Person’s genetics and environment likely risk factors for Parkinson’s
The study, “Association Between Body Composition Patterns, Cardiovascular Disease, and Risk of Neurodegenerative Disease in the UK Biobank,” was published in Neurology.
How Parkinson’s arises is not exactly known, but various genetic and environmental risk factors are thought to be contributory disease causes. The same is true for other neurodegenerative conditions, including Alzheimer’s.
Accumulating evidence suggests that aspects of body composition, like fat, muscle, and bone mass, also contribute to disease risk — with muscle seeming to be more protective and fat tending to elevate risk. But the exact nature of these relationships still is being explored.
Scientists at Sichuan University in China looked at the link between body composition and neurodegenerative disease using data covering 412,691 adults enrolled between 2006-2010 in the U.K. Biobank, a large health registry of people living in Great Britain and Northern Ireland.
Participants, with a mean age of 56, did not have a neurodegenerative disease at enrollment. At that time, they underwent body composition assessments that included waist and hip measurements, grip strength, bone density, and fat and muscle mass. Starting five years after enrollment, they were followed for a mean of nine years, with this study’s scientists looking into a neurodegenerative disease diagnosis and its associated factors.
A total of 8,224 people developed neurodegenerative conditions over those years, including 2,427 cases of Parkinson’s disease, 2,933 cases of Alzheimer’s, and 6,076 people with dementia due to any other cause.
Across both men and women, different body composition profiles were associated with varying risk of these diseases.
Central obesity seen to raise risk by 13%, arm-dominant fat by 18%
People with a greater degree of central obesity — excess fat in the abdominal area, or belly fat — had 13% higher odds of a neurodegenerative condition relative to people with less belly fat. Indeed, most individual indicators that linked with central obesity, such as a high waist-to-hip ratio, also associated with higher rates of neurodegenerative disease.
A greater arm-dominant fat distribution pattern, where fat mass is mainly found in the arms, associated with an 18% higher risk of neurodegeneration.
Conversely, people with greater overall muscle strength were found to be 26% less likely to develop neurodegenerative conditions relative to those with poorer muscle strength.
Likewise, biomarkers of poor brain aging were more evident in people who went on to be diagnosed with a neurodegenerative disease relative to those who did not. These biomarkers also positively correlated with central obesity and arm-dominant fat patterns, while muscle strength negatively correlated with them.
The relationships seen between body composition and neurodegenerative disease risk also held regardless of a person’s genetic or family history risk for these conditions.
Overall, “our findings … confirm the substantial influence of body composition on the risk of neurodegenerative diseases in middle-aged individuals,” the researchers wrote.
Cardiovascular health of adults with more central and arm fat also poorer
The scientists believe these findings could inform more effective and targeted interventions for preventing neurodegenerative disease, rather than just promoting overall weight loss.
“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,” Song said.
Moreover, the observed relationships between body composition and disease risk partly could be explained by the poorer cardiovascular health seen in people with more central and arm fat, and lesser muscle strength. This group also was more likely to have heart disease or a stroke during follow-up. Around 10% to 35% of the observed relationships could be explained by cardiovascular conditions, the researchers noted.
“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,” Song said.
A study limitation was data mainly covering white adults in the U.K. “Further research involving diverse ethnic cohorts is essential to confirm our findings,” the researchers wrote.
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