Summary: A new study reports a correlation between increased muscle adiposity and an elevated risk of cognitive decline. Researchers found that a 5-year increase in thigh muscle fat was a standalone risk factor for cognitive deterioration.
This relationship persisted regardless of total weight, other fat deposits, muscle characteristics, or traditional dementia risk factors.
The study hints at the potential of muscle adiposity as a unique biomarker for assessing cognitive decline risk.
- A 5-year increase in thigh muscle fat was found to be a standalone risk factor for cognitive decline in adults aged 69-79.
- The risk relationship was independent of total weight, other fat deposits, muscle characteristics, and traditional dementia risk factors.
- The findings suggest that muscle adiposity could play a unique role in cognitive decline, distinct from other types of fat or muscle characteristics.
New research reveals that the level of fat within the body’s muscle—or muscle adiposity—may indicate a person’s likelihood of experiencing cognitive decline as they age.
In the study published in the Journal of the American Geriatrics Society, 5-year increase in fat stored in the thigh muscle was a risk factor for cognitive decline.
This risk was independent of total weight, other fat deposits, and muscle characteristics (such as muscle strength or mass) and also independent of traditional dementia risk factors.
Increases in muscle adiposity from year 1 to year 6 were associated with faster and more cognitive decline over time. Credit: Neuroscience News
Investigators assessed muscle fat in 1,634 adults 69–79 years of age at years 1 and 6 and evaluated their cognitive function at years 1, 3, 5, 8, and 10.
Increases in muscle adiposity from year 1 to year 6 were associated with faster and more cognitive decline over time. The findings were similar for Black and white men and women.
“Our data suggest that muscle adiposity plays a unique role in cognitive decline, distinct from that of other types of fat or other muscle characteristics,” said corresponding author Caterina Rosano, MD, MPH, of the University of Pittsburgh’s School of Public Health.
“If that is the case, then the next step is to understand how muscle fat and the brain ‘talk’ to each other, and whether reducing muscle adiposity can also reduce dementia risk.”
Increase in skeletal muscular adiposity and cognitive decline in a biracial cohort of older men and women
Obesity and loss of muscle mass are emerging as risk factors for dementia, but the role of adiposity infiltrating skeletal muscles is less clear. Skeletal muscle adiposity increases with older age and especially among Black women, a segment of the US population who is also at higher risk for dementia.
In 1634 adults (69–79 years, 48% women, 35% Black), we obtained thigh intermuscular adipose tissue (IMAT) via computerized tomography at Years 1 and 6, and mini-mental state exam (3MS) at Years 1, 3, 5, 8 and 10. Linear mixed effects models tested the hypothesis that increased IMAT (Year 1–6) would be associated with 3MS decline (Year 5–10). Models were adjusted for traditional dementia risk factors at Year 1 (3MS, education, APOe4 allele, diabetes, hypertension, and physical activity), with interactions between IMAT change by race or sex. To assess the influence of other muscle and adiposity characteristics, models accounted for change in muscle strength, muscle area, body weight, abdominal subcutaneous and visceral adiposity, and total body fat mass (all measured in Years 1 and 6). Models were also adjusted for cytokines related to adiposity: leptin, adiponectin, and interleukin-6.
Thigh IMAT increased by 4.85 cm2 (Year 1–6) and 3MS declined by 3.20 points (Year 6–10). The association of IMAT increase with 3MS decline was statistically significant: an IMAT increase of 4.85 cm2 corresponded to a 3MS decline of an additional 3.60 points (p < 0.0001), indicating a clinically important change. Interactions by race and sex were not significant.
Clinicians should be aware that regional adiposity accumulating in the skeletal muscle may be an important, novel risk factor for cognitive decline in Black and White participants independent of changes to muscle strength, body composition and traditional dementia risk factors.