Sarcopenia is Associated With Impairment of Activities of Daily Living in Japanese Patients With Early-Stage Alzheimer Disease

Alzheimer disease (AD) is the most common type of dementia. Since there is no basic treatment for AD at present, prevention of AD and care of AD patients are the most urgent challenges. Besides progressive neuropsychiatric deficits, impairment of activities of daily living (ADL) is a characteristic feature of AD.1 The diagnosis and clinical stages of AD are determined by the degree of ADL impairment.2 Prevention of ADL impairment is thus crucial for successful management of AD. Although reasons for ADL impairment in AD may be multifactorial, and include cognitive decline and behavioral and psychological symptoms of dementia (BPSD),3 the detailed mechanism of ADL impairment remains unclear. Recently, nutritional problems and sarcopenia, which is a concept consisting of decreased muscle mass and strength with mobility impairment,4 have received attention in relation to impaired cognitive function. Weight loss often occurs before the diagnosis of dementia, and progresses as disease severity increases. In early-stage AD, total lean mass is reduced and associated with brain atrophy and cognitive function.5 Moreover, our previous study showed that the prevalence of sarcopenia was increased in patients with mild cognitive impairment and AD compared with that in subjects with normal cognition. In addition, factors associated with sarcopenia include low vitality, which is the most common psychiatric symptom of dementia.6 It seems that dementia-associated symptoms such as cognitive decline and low vitality induce sarcopenia even in earlystage AD, resulting in ADL impairment, while decreased muscle mass and strength promote further cognitive decline.5 To our knowledge, very little is known about the impact of sarcopenia on ADL impairment in AD patients. We hypothesized that sarcopenia plays a pivotal role in ADL impairment even in early-stage AD. The aim of this study was to clarify the factors associated with ADL impairment, with consideration of the involvement of sarcopenia in early-stage AD.