Masseter muscle volume might be a key indicator of sarcopenia risk in older adults

As populations age, the prevalence of sarcopenia—a progressive loss of muscle mass and function—has become an increasingly urgent public health concern. Sarcopenia increases the risk of falls and frailty, reduces the quality of life for older adults, and heightens the likelihood of requiring long-term care. Preventing sarcopenia is, therefore, crucial for alleviating this healthcare burden.

A pioneering study conducted by researchers from Juntendo University in Japan sheds light on this issue. The research group comprising researcher Abulaiti Abudurezake at the Sportology Center, Graduate School of Medicine, Juntendo University, along with Assistant Professor Saori Kakehi and Professor Yoshifumi Tamura from the Department of Sports Medicine and Sportology, investigated the relationship between masseter muscle volume (MMV) and sarcopenia in community-dwelling older adults aged 65 years and older. Their aim was to clarify the relationship between MMV and sarcopenia, as well as to compare the determinants of MMV and appendicular skeletal muscle mass (ASMM) to explore early detection methods. Their findings were made available online on 14 October 2024 and was published in Volume 56, Issue 1 of the Archives of Medical Research on 1 January 2025.

The study involved a comprehensive analysis of MMV and its association with sarcopenia among older individuals. Using magnetic resonance imaging (MRI) to measure MMV, the study examined various influencing factors, including BMI or body mass index, lifestyle factors such as activity levels and nutritional intake, insulin-like growth factor 1 (IGF-1) levels, and the ACTN3 R577X polymorphism. Statistical analyses, including multiple regression, were used to identify factors independently associated with MMV and ASMM.

Dr. Saori Kakehi explains their findings, “Our results revealed that men with the lowest MMV exhibited a 6.6-fold increased risk of sarcopenia, while women faced a 2.2-fold increased risk compared to those with the highest MMV.” They identified age and BMI as key factors affecting ASMM for both men and women. In contrast, while BMI influenced MMV, the ACTN3 R577X polymorphism and IGF-1 levels emerged as key indicators for men, whereas smoking and IGF-1 levels played significant roles in women. These results suggest distinct determinants of MMV and limb skeletal muscle mass, and that their respective effects on muscle mass are not uniform. Specifically, MMV is strongly influenced by genetic factors and hormones, while age and BMI significantly affect limb skeletal muscle mass.

Discussing the study’s implications, Dr. Kakehi stated, "Our findings suggest that incorporating measurement of MMV to MRI examinations could lead to early diagnosis and risk assessment of sarcopenia. This approach could help establish personalized medicine and prevention programs that consider genetic factors." She further noted, "Our research provides a new method for early sarcopenia diagnosis through MRI measurement of MMV. To prevent sarcopenia is crucial to extending healthy life spans and reducing medical expenses. By enabling earlier detection and personalized interventions, our findings can contribute to more effective sarcopenia prevention, ultimately supporting longer, healthier lives and easing the financial burden on the healthcare system."

In conclusion, this study establishes a clear connection between low MMV and increased sarcopenia risk, particularly in older men. It highlights the multifaceted role of MMV, influenced by both genetic and environmental factors, in assessing muscle health in older adults. By identifying MMV as a key marker, this research lays the groundwork for future studies and interventions focused on promoting muscle health in the aging population, ultimately improving their well-being and quality of life.

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About Assistant Professor Saori Kakehi

Dr. Saori Kakehi is an accomplished researcher and Assistant Professor at Juntendo University’s Department of Sports Medicine and Sportology. Specializing in muscle insulin resistance, physiology, and medicine, she has authored 79 publications, making significant contributions to the academic community, with an h-index of 16 reflecting the impact of her work. Dr. Kakehi's research continues to influence the understanding of muscle insulin resistance and its implications for medical science.