Appendicular skeletal muscle mass, physical activity, and cognitive status in patients with Alzheimer's disease

Objective: To examine the interrelations among appendicular skeletal muscle mass and physical activity, energy intake, and cognitive status in free-living patients with AD. Background: Increasing disease severity in AD patients may contribute to poor nutritional status and loss of skeletal muscle mass. This may lead to impaired physical function and loss of functional independence. Methods: Participants in our study were 30 noninstitutionalized AD patients (74 +/- 8 years) and 30 healthy age- and body mass index-matched control subjects (73 +/- 7 years). We measured appendicular skeletal muscle mass by dual-energy X-ray absorptiometry, energy expenditure by doubly labeled water, and energy intake by food diaries. Results: As expected, the AD group had lower Mini-Mental State Examination scores than the control subjects (p < 0.05). No differences in energy intake or energy expenditure and its components were noted between the groups. Higher levels of appendicular muscle mass in AD patients were associated with increased energy expenditure of physical activity (r = 0.52, p < 0.01) and daily energy intake (r = 0.49, p = 0.01). Cognitive status was not related to appendicular muscle mass, daily energy intake, or energy expenditure of physical activity in AD patients. Conclusions: Higher levels of physical activity and energy intake are associated with higher appendicular skeletal muscle mass in AD patients. Nutritional and physical activity interventions may represent practical and inexpensive strategies in their therapeutic management.