The body types that raise your risk of Alzheimer's, according to major study

Having more fat around your arms or belly could raise your risk of Alzheimer's and Parkinson's, a major study suggests.

Researchers have discovered that those who carry weight in these areas — often dubbed 'beer bellies' and 'bingo wings' — appear to have a higher risk of the diseases, while people with more muscle are at a lower risk. 

The study involved 412,691 people, average age 56, who were followed for nine years. 

At the beginning of the study, measurements were taken for body composition, such as waist and hip measurements, grip strength, bone density and fat and lean mass.

During the study, 8,224 people developed neurodegenerative diseases — mainly Alzheimer's disease, other forms of dementia, and Parkinson's disease. 

After adjusting for other factors that could affect the rate of disease, such as high blood pressure, smoking and drinking status and diabetes, researchers found that overall people with high levels of belly fat were 13 percent more likely to develop these diseases than people with low levels of belly fat.

People with high levels of arm fat were 18 percent more likely to develop the diseases than those with low levels of arm fat.

However, those with high muscle strength were 26 percent less likely to develop the diseases than those with low levels of strength.

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Dr Huan Song, lead study author and epidemiologist at Sichuan University in China, said: '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 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.'

The link between bingo wings and belly fat and these diseases was partly explained by the occurrence of heart disease and stroke during the study, the researchers said. 

'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,' Professor Song said.

The findings were published in the journal Neurology, the medical journal of the American Academy of Neurology.

Visceral fat wraps around abdominal organs deep inside the body, whereas subcutaneous fat is under the skin. Even people with a healthy BMI can have a significant amount of visceral fat 

The above shows the prevalence of dementia - proportion of people that have dementia - by year from 2000 to 2016. It reveals a gradual decline in rates

Belly fat is typically made up of subcutaneous fat and visceral fat. Subcutaneous is just beneath the skin, while visceral surrounds vital organs like the heart.  

The researchers noted that fat storage around the hips and upper thighs 'has been linked to health benefits, mainly because it could guard against ectopic fat deposition within vital organs (e.g., muscles), enhance insulin sensitivity, and reduce inflammation.'

Ectopic fat builds up inside essential organs like the liver and the heart, contributing to issues like heart disease and fatty liver disease. 

The researchers wrote: 'Our study contributes novel insights by identifying significant associations between “leg-dominant fat distribution” and “arm-dominant fat distribution” patterns with neurodegeneration risk, emphasizing the pivotal role of fat and muscle distribution in predicting and potentially mitigating neurodegenerative diseases, beyond traditional weight metrics.'

There were several limitations, with the team mainly noting that participants were largely white people from the UK and Northern Ireland, leading to a less diverse sample size. 

'Further research involving diverse ethnic cohorts is essential to confirm our findings,' the researchers wrote.