Japan is a country that has been known for its longevity and low ageing rate of 25% (compared to other countries), which has spurred a vast amount of age-related research pertaining to the Japanese population. Much of this research has placed significant attention of sarcopenia, along with the accompanying decrease in muscle strength and motor function, as these factors can lead to weakness and increase the need for nursing care for older adults. Past studies have shown that a systemic decrease in muscle mass is a marker for low nutritional status and less frequent physical activity. Moreover, associations between swallowing function and systemic disease, oral function, and nutritional status among the elderly who need nursing care have also been disclosed. However, not many studies have examined the connection between swallowing function and the systemic decreases in muscle mass.
Past studies have shown various risk factors for dysphagia among elderly people who need nursing care. For example, if a systemic decrease in muscle mass lowers one’s swallowing ability, their nutritional status could also decrease, leading to a vicious cycle. However, muscle mass can be enhanced by improving nutritional status and physical activity, and it may be an important guideline for examining swallowing rehabilitation in instances of dysphagia that are caused by aging. Thus, a recent study used skeletal muscle mass (as examined using the Skeletal Muscle Index [SMI]) as a marker of nutritional status and physical activity, and aimed to clarify the association between SMI and dysphagia in these patients.
The results of the study showed that decreased tongue motility and decreased SMI are risk factors for dysphagia. Furthermore, a decrease in SMI was a significant risk factor for decreased swallowing ability.
Muscles go through a repetitive cycle of protein synthesis and breakdown, and muscle mass diminishes during aging as the rate of breakdown surpasses the rate of synthesis; the reduction in muscle mass occurs when this imbalance becomes critical. Nutritional habits, such as taking amino acids and vitamin D, are necessary to properly manage protein synthesis, and the decreased nutritional status that happens when aging influences the muscle mass of the entire body, including the muscles associated with swallowing. Therefore, these changes can result in the decrease of swallowing function.
Due to the increase in average lifespan and the development of disease prevention interventions, researchers of the study predict that an increase of older adult patients who experience diminished ability to swallow without a clear cause (i.e. stroke) will occur. Health care providers should be knowledgeable about the risk factors that occur due to the effects of sarcopenia and should screen their older adult patients for declining swallowing ability as a result of aging and poor nutrition by using effective oral function assessment methods and systemic muscle mass assessment. By using these methods, elderly patients can be provided with the nutritional therapy and rehabilitation they need.