Losing muscle as we age could be an important warning sign for dementia, according to new Curtin University research.
Researchers analysed more than 80 studies examining the links between body weight, body fat, muscle health and dementia, finding people with sarcopenia – the loss of muscle mass and strength – had a 42 per cent higher risk of dementia.
The findings also revealed a surprising difference in how obesity was linked to dementia depending on a person’s age.
People with obesity in middle age, or before 65, had a nine per cent higher risk of dementia, while obesity in people aged 65 and over was linked to a 17 per cent lower risk.
Lead researcher Dr Uraiporn Booranasuksakul, from Burapha University, said the findings showed that body weight alone did not tell the full story when it came to dementia risk.
“It’s not just about how much you weigh – maintaining muscle strength and function also appears to be important as we age,” Dr Booranasuksakul said.
“Our findings suggest losing muscle could be an important warning sign for dementia risk.”
Sarcopenia is a condition where people lose a greater amount of muscle mass, strength and physical function, often as they get older.
Dr Booranasuksakul said the findings highlighted the importance of looking after muscle health throughout life.
“Maintaining muscle is an important part of healthy ageing, and regular physical activity and good nutrition can help support muscle strength and function,” she said.
Corresponding author Professor Mario Siervo, from Curtin’s School of Population Health, said the findings also challenged the idea that dementia risk could be understood simply by looking at a person’s weight.
“We found that obesity in middle age was linked to a higher risk of dementia, but this relationship changed in later life,” Professor Siervo said.
“This does not mean people should gain weight as they get older. Rather, it shows us that the relationship between body weight, ageing and dementia is complex.”
The researchers also looked at sarcopenic obesity, where a person has both low muscle mass or function and excess body fat.
Only four studies met the criteria for this part of the analysis, and researchers found no statistically significant link between sarcopenic obesity and dementia.
Professor Siervo said more research was needed to understand whether the combination of muscle loss and excess body fat affected dementia risk.
“There is still a lot we don’t know about how changes in muscle and body fat interact over time,” Professor Siervo said.
“More long-term research is needed to understand whether having both low muscle mass and excess body fat increases dementia risk.”
The researchers said the findings reinforced the importance of taking a life-long approach to maintaining healthy body composition, including preventing unhealthy weight gain during middle age and maintaining muscle strength and function as people get older.
Professor Warren Harding AM, Chairman and Head of Research and Partnerships at Alzheimer’s WA, welcomed the findings and congratulated Curtin on its investment into dementia research.
“Dementia is a $2.8 trillion global challenge and the findings from the World Health Organization and the Lancet Commission on the 14 lifestyle risk factors are powerful reminders of the importance of early detection and good eating, exercise, weight, hearing, vision and brain training,” Professor Harding said.
“The Curtin findings around muscle mass and strength also reinforce the importance of exercise and underlines the importance of good mobility and stability to reduce falls as people age.”
The study was led by researchers from Curtin University’s School of Population Health and Dementia Centre of Excellence, in collaboration with researchers from Australia, the UK, Canada, Thailand and Italy.
The paper, titled ‘Sarcopenia, Obesity, Sarcopenic Obesity and Dementia Risk: A Systematic Review and Meta-Analysis of Cohort Studies’, was published in International Journal of Food Sciences and Nutrition.
