Researchers analysed more than 80 studies investigating the relationship between body weight, body fat, muscle health and dementia. The analysis found that people with sarcopenia—a condition involving significant loss of muscle mass and strength—had a 42 per cent higher risk of developing dementia.

The researchers also identified an age-related difference in the association between obesity and dementia. Obesity during middle age, defined as before age 65, was associated with a nine per cent higher risk of dementia. In contrast, obesity among adults aged 65 and older was associated with a 17 per cent lower risk.

Lead researcher Dr Uraiporn Booranasuksakul of Burapha University said the findings demonstrated that body weight alone was not enough to understand dementia risk.

The study suggested that preserving muscle strength and physical function may be an important part of healthy ageing. Dr Booranasuksakul noted that declining muscle health could potentially serve as an early warning indicator of dementia risk.

Sarcopenia typically develops with ageing and is characterised by a substantial decline in muscle mass, strength and physical performance. The researchers therefore highlighted the importance of maintaining muscle health throughout life through regular physical activity and adequate nutrition.

Corresponding author Professor Mario Siervo from Curtin University’s School of Population Health said the findings also highlighted the complex relationship between body weight, ageing and dementia. While obesity in middle age was associated with increased dementia risk, this relationship appeared to change in later life. The researchers stressed that the findings should not be interpreted as a reason for older adults to gain weight.

The team also examined sarcopenic obesity, a condition involving both reduced muscle mass or function and excess body fat. However, only four studies met the criteria for this part of the analysis, and no statistically significant association between sarcopenic obesity and dementia was identified.

Professor Siervo said further long-term research is needed to determine how changes in muscle mass and body fat interact over time and whether their combination influences dementia risk.

Overall, the findings support a lifelong approach to maintaining healthy body composition. This includes preventing unhealthy weight gain during middle age while preserving muscle strength, mobility and physical function in later life.

Professor Warren Harding AM, Chairman and Head of Research and Partnerships at Alzheimer’s WA, welcomed the findings and highlighted the broader importance of lifestyle factors in dementia prevention. He noted that research from the World Health Organization and the Lancet Commission has emphasised the role of factors such as healthy eating, physical activity, weight management, hearing, vision and cognitive health.

The findings on muscle mass and strength further reinforce the importance of regular exercise, mobility and physical stability as people age, particularly in supporting independence and reducing the risk of falls.

Source: https://www.curtin.edu.au/news/media-release/new-dementia-warning-sign-hiding-in-our-muscles-curtin-study-finds/