As reported on SciTechDaily, a large research review suggests age-related losses in muscle mass, strength, and physical function may have a stronger association with dementia risk than obesity alone.
Maintaining muscle health may deserve greater attention in conversations about healthy brain aging, according to a review of more than 80 studies examining the relationship between body composition and dementia.
Researchers led by Curtin University evaluated evidence involving body weight, body fat, and muscle health. Among the factors studied, sarcopenia showed the strongest association with dementia. People with the condition had a 42% greater risk of dementia.
Sarcopenia is characterized by substantial declines in muscle mass, muscular strength, and physical performance, changes that become increasingly relevant with advancing age.
Weight and Dementia Risk May Change With Age
The review also found that the relationship between obesity and dementia differed depending on age.
Among adults younger than 65, obesity was associated with a 9% increase in dementia risk. In adults 65 and older, however, obesity was associated with a 17% lower risk.
The researchers cautioned that the latter finding should not be interpreted as evidence that gaining excess weight later in life protects the brain. Instead, the differing results illustrate how the relationship among aging, body composition, and dementia can change across the lifespan.
The findings also suggest that body weight or body mass alone may provide an incomplete picture of health in older adults. Measures of strength, muscle quantity, and physical function could potentially add useful information when considering healthy aging and dementia risk.
Preserving Muscle May Have Broader Benefits
Lead researcher Dr. Uraiporn Booranasuksakul of Burapha University emphasized that healthy aging involves more than maintaining a certain weight. The results suggest that deterioration in muscle strength and physical function could represent an important signal when evaluating dementia risk.
The researchers highlighted physical activity and nutritious eating as established ways of supporting muscle strength and function with age.
Maintaining mobility has benefits beyond its possible relationship with dementia. Stronger muscles and better physical function can also support balance and stability as people grow older, potentially helping address concerns surrounding falls and loss of independence.
Questions Remain About High Body Fat and Low Muscle
The review additionally examined sarcopenic obesity, a condition in which excess body fat occurs alongside impaired muscle mass or function.
Evidence in this area remains limited. Only four studies qualified for that portion of the analysis, and the pooled findings did not demonstrate a statistically significant association between sarcopenic obesity and dementia.
The researchers said additional long-term studies will be necessary to clarify how muscle and fat changes interact over time and whether the combination of excess body fat and poor muscle health carries dementia implications beyond either factor alone.
A Lifespan Approach to Body Composition
Overall, the findings point toward a more nuanced view of body composition and brain health.
Rather than focusing exclusively on the number on the scale, healthy-aging strategies may need to consider how an individual’s muscle mass, strength, physical performance, and body fat change over time. The results support efforts to prevent unhealthy weight gain during midlife while also emphasizing the preservation of muscle and physical function later in life.
Professor Warren Harding AM, chairman and head of research and partnerships at Alzheimer’s WA, said the findings reinforce the broader importance of exercise in healthy aging. He also noted that maintaining strength, mobility, and stability can have practical benefits for reducing fall risk.
The study adds muscle health to a growing discussion about potentially modifiable factors associated with dementia. While the findings do not establish that sarcopenia causes dementia, they suggest that declining muscle health may be an important marker to consider as researchers continue investigating strategies for healthier cognitive aging.
