Most of the older adult population worldwide experiences cognitive decline with age. Disability is often associated with cognitive impairment; thus, interventions for preventing cognitive decline are critically needed. Sarcopenia is the age-related deterioration of skeletal muscle mass that is highly prevalent and a crucial problem among the elderly. Studies have shown that sarcopenia and cognitive impairment are related to frailty. Thus, prevention of sarcopenia is imperative for mitigating age-related healthcare issues.
A recent study sought to determine the extent to which sarcopenia is a risk factor of cognitive decline in older adults. Participants were 131 healthy volunteers aged 65 years and older. Data was collected for one year from September 2014 to September 2015. Sarcopenia was diagnosed in participants who had slow walking speed (less than or equal to 0.8 m/s), low grip strength (less than 26 kg for men and less than 18 kg for women), and low skeletal muscle mass, measured by using a bioelectrical impedance data acquisition system. Participants’ level of cognitive functioning was assessed using the Mini-Mental State Exam (MMSE), which is a short screening standard test that assesses the mental status of aging individuals. The MMSE is made up of the following five domains for identifying cognitive impairment: orientation, registration, attention and calculation, memory, and language. It consists of eleven questions with 30 as the maximum possible score. The higher the score indicates better cognitive performance. Participants took the MMSE at the beginning and end of the year-long data collection period.
The researchers found that out of 131 participants, 10 (7.6%) were diagnosed with sarcopenia and the rest were normal. There were no significant variances in sex, socioeconomic background, and level of education, but there were significant differences in age and body mass index (BMI). Furthermore, participants with sarcopenia performed significantly worse on the MMSE, with low scores both pre- and post-data collection compared with the participants identified as normal. The rate of decline in pre- and post-MMSE scores also showed significant difference between the two groups.
The results of this one-year study showed that older adults with sarcopenia had greater severity of cognitive decline, and sarcopenia was an independent risk factor of cognitive impairment in the elderly.
Researchers of the study posit that successive lifestyle changes, such as disability and low physical activity due to decline in muscle strength and walking speed, can influence the decline of cognitive functioning. A significant relationship exists between level of physical activity and functional ability, and level of physical performance has been consistently found to be a marker of future cognitive deterioration. Moreover, low levels of physical activity due to sarcopenia could lead to decreased expression of neurotrophic factor and insulin-like growth factor derived from the brain, which are associated with physical activity and play significant roles in learning and neural plasticity. Thus, sarcopenia is a causal factor of physical inactivity and can negatively affect the expression of these factors, consequently leading to future cognitive deterioration.
The study’s results indicate that sarcopenia significantly increases the risk of cognitive decline in elderly people. Older adults in nursing homes and assisted living facilities are especially vulnerable to sarcopenia and cognitive decline. Many of these elderly individuals are frail and must be given quality of care by nursing home or assisted living facility staff. Residents should be encouraged to engage in appropriate forms of exercise that strengthen muscles and slow the progression of muscle deterioration.