The relationship between functional level, cognitive status, sleep quality and quality of life in patients with Alzheimer’s disease: a cross-sectional study

Background Functional deficits and loss of cognitive functions in patients with Alzheimer’s disease (PwAD) may affect activities of daily living (ADLs), sleep quality and quality of life (QoL). However, studies investigating the multiple relationship between cognitive status, functional level, ADL, sleep quality and health-related QoL in PwAD are limited.Objectives This study was to investigate the multiple relationships among functional level, cognitive status, sleep quality, and QoL in PwAD.Methods A total of 47 individuals diagnosed with mild to moderate Alzheimer’s disease were included. Cognitive status was assessed using the Montreal Cognitive Assessment. Motor function was evaluated via the Rivermead Motor Assessment. ADLs were measured using the Modified Barthel Index and Katz ADL Scale. Sleepiness levels were determined using the Epworth Sleepiness Scale, sleep quality was assessed with the Pittsburgh Sleep Quality Index, and QoL was evaluated using the Alzheimer’s Disease-Related Quality of Life Scale.Results The study demonstrated that as cognitive impairment progressed in PwAD, functional limitations in ADLs increased, while sleep quality significantly declined (r = −458, p < 0.05). Both cognitive decline and ADLs limitations were independently associated with reduced sleep quality, and this interplay may contribute to the deterioration of overall QoL (r = −0.475, p < 0.05). Furthermore, higher educational attainment was found to be protective against cognitive decline (p < 0.05).Conclusions These findings reveal the importance of preserving cognitive and functional levels in PwAD, and suggest that sleep quality should be routinely evaluated in these patients.