Muscle quality linked to cognitive health in middle age

Over the past decade, much research has focused on the connection between skeletal muscle health and cognitive disorders. Scientists have found that sarcopenia, a geriatric syndrome characterized by progressive loss of skeletal muscle mass and function, appears to be strongly associated with an elevated risk of dementia. The complex relationship between our muscles and brain health represents a promising frontier in preventive medicine, particularly as global populations continue to age. 

However, to date, most studies on the link between muscle health and dementia have predominantly targeted elderly populations or individuals already diagnosed with cognitive impairment. Thus, how muscle parameters relate to cognitive function in broader populations remains largely underexplored. This is especially true for middle-aged individuals who might be in the earliest stages of cognitive decline-those most likely to benefit from early interventions.

In a recent paper made available online on May 8, 2025, and published in Volume 16, Issue 3 of the Journal of Cachexia, Sarcopenia and Muscle on June 1, 2025, a research team led by Postdoctoral Researcher Kentaro Ikeue from Graduate School of Health and Sports Science, Doshisha University, Japan, addressed this knowledge gap. They conducted a cross-sectional study involving 263 participants from the general Japanese population, seeking to answer a critical question: which indices encompassing skeletal muscle quantity, quality, and strength best reflect cognitive decline in individuals aged over 40? The study was co-authored by Professor Kojiro Ishii from Doshisha University and Professor Noriko Satoh-Asahara from NHO Kyoto Medical Center.

The key sarcopenia-related indices explored included appendicular skeletal muscle mass (ASM) by height, ASM by body mass index, handgrip strength (HGS), HGS by upper extremity skeletal muscle mass, and phase angle (PhA). To clarify, this last one refers to a bioelectrical impedance measurement that reflects cellular integrity and muscle quality. The researchers analyzed how these indices correlated with cognitive function, assessed using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). This comprehensive tool evaluates multiple cognitive domains, including memory, attention, language, and executive function.

Interestingly, PhA emerged as the most significant measure. "We found that a higher phase angle is associated with a lower risk of mild cognitive impairment in women," explained Dr. Ikeue, "Additionally, a higher phase angle was linked to better memory in both men and women, which is particularly noteworthy since memory decline is often the earliest manifestation of cognitive impairment."

The researchers noted interesting sex-based differences in their findings. While PhA correlated with multiple cognitive domains in women-including memory, language, executive function, and attention-it was primarily associated with memory function in men. This suggests that the relationship between muscle quality and cognitive function may follow different patterns in men and women, possibly influenced by hormonal differences or other sex-specific factors.

These results have important implications for public health practices, suggesting that muscle quality assessments in clinical or routine checkups could help identify individuals at increased risk of cognitive decline. According to the research team, measuring phase angle, which is quick and convenient, could become a standard component of annual health examinations, providing valuable early warning signs for various disorders. "Our findings suggest that phase angle is not only useful for assessing sarcopenia but also serves as a potential marker for early cognitive decline," noted Dr. Ikeue.

By helping identify individuals with declining muscle quality, healthcare providers might be able to initiate interventions-such as targeted exercise programs or nutritional strategies-before cognitive symptoms emerge. "Adopting personal behaviors aimed at improving muscle quality may serve as a preventative measure against dementia, especially in women," added Dr. Ikeue, "Thus, our study contributes to the development of innovative strategies to prevent both sarcopenia and dementia within the general population."

Overall, this work represents an important step forward in understanding the complex relationships between muscle health and cognitive function throughout adulthood-not just in later years.