Exploring sarcopenia as a predictive factor for the development of cognitive dysfunction

As the lifespan of our population increases, dementia has become more prevalent causing a dramatic deterioration in quality of life and is a significant burden to caregivers and our health care system. Unfortunately, currently available treatments are few and have inadequate efficacy. It would be most useful to be able to identify people at risk of developing dementia and be able to institute preventative measures. Therefore, it is critical to identify people at high risk of dementia. Decreased muscle mass has been proposed to be associated with dementia, but results of various studies have been conflicting. We propose to use the large size of the CLSA cohort to determine not only whether decreased muscle mass is associated with dementia, but whether it is associated with cognitive decline and future onset of dementia. If such a predictive relationship is identified, treatments that are now appearing for muscle wasting could be tested for their ability to prevent the onset of dementia.

The loss of muscle mass and strength, called sarcopenia, is a typical feature of aging leading to decline in physical function and capacity. In parallel, cognitive functions also decline. Researchers questioned whether these declines were not parallel but rather related. As a first step, they analysed the CLSA comprehensive cohort dataset from more than 8,000 participants 65 years and older to establish what is a low level of muscle mass and muscle strength. They have identified specific thresholds for men and women that reflect a low level of physical functioning. Then, they asked the question whether having low muscle predicts subsequent cognitive decline in three domains ─ memory, executive function and psychomotor speed ─ in older adults. Results showed that indeed, those with a low muscle mass at baseline experienced faster decline in executive functions during the following 3 years. Executive functions are responsible for organizing our thoughts, making decisions, sustaining attention, among others, and are thus important in day-to-day activities and behaviours. Interestingly, the association of low muscle mass and cognitive decline was still present when accounting for the level of physical activity and muscle strength, suggesting that muscle mass may be an independent factor. Muscle mass being a modifiable factor, future studies will investigate whether maintaining muscle over time prevents cognitive decline.