A new study has found low muscle mass and strength in the context of high fat mass may be an important predictor of cognitive performance in older adults.
Investigators call the combination of less muscle plus high fat “skinny fat.”
While sarcopenia, the loss of muscle tissue that is part of aging, as well as obesity can negatively impact overall health and cognitive function, the new investigation finds their coexistence poses an even higher threat, surpassing their individual effects.
“Sarcopenia has been linked to global cognitive impairment and dysfunction in specific cognitive skills including memory, speed, and executive functions,” said senior author James E. Galvin, M.D., M.P.H.
“Understanding the mechanisms through which this syndrome may affect cognition is important as it may inform efforts to prevent cognitive decline in later life by targeting at-risk groups with an imbalance between lean and fat mass.”
The study, led by researchers at Florida Atlantic University’s Comprehensive Center for Brain Health, appears in the journal Clinical Interventions in Aging.
Using data from a series of community-based aging and memory studies of 353 participants, the researchers assessed the relationship of sarcopenic obesity or skinny fat with performance on various cognition tests.
The average age of the participants was 69. Data included a clinic visit, valid cognitive testing such as the Montreal Cognitive Assessment and animal naming; functional testing such as grip strength and chair stands; and body composition (muscle mass, body mass index, percent of body fat) measurements.
Results from the study show that sarcopenic obesity or skinny fat was associated with the lowest performance on global cognition, followed by sarcopenia alone and then obesity alone.
Obesity and sarcopenia were associated with lower executive function such as working memory, mental flexibility, self-control and orientation when assessed independently and even more so when they occurred together.
Using a cross-sectional design, the researchers found consistent evidence to link sarcopenic obesity to poor global cognitive performance in the study subjects. This effect is best captured by its sarcopenic component with obesity likely having an additive effect.
This effect extends to specific cognitive skills, in particular executive function — the mental processes that enable us to plan, focus attention, remember instructions and juggle multiple tasks.
The exact mechanisms linking obesity to cognitive dysfunction are yet to be determined, although several pathways including sedentary behavior, inflammation, and vascular damage have been proposed.
Sarcopenia, in turn, has been linked to impairments in abilities that relate to conflict resolution and selective attention. Executive function is reduced in obese older adults, and improvement in muscular function has been linked to enhancement of executive function in senior adults.
Galvin and his study collaborators, Magdalena I. Tolea, Ph.D., a research assistant professor of integrated medical science, and Stephanie Chrisphonte, M.D., a research assistant professor of integrated medical science, caution that changes in body composition including a shift toward higher fat mass and decreased lean muscle mass represent a significant public health concern among older adults.
The combination of body changes may lead to various negative health outcomes including cardiovascular and neurodegenerative diseases.
“Sarcopenia either alone or in the presence of obesity, can be used in clinical practice to estimate potential risk of cognitive impairment,” said Tolea. “Testing grip strength by dynamometry can be easily administered within the time constraints of a clinic visit, and body mass index is usually collected as part of annual wellness visits.”
Source: Florida Atlantic University