High prevalence of sleep disorders and behavioral and psychological symptoms of dementia in late-onset Alzheimer disease A study in Eastern China

Alzheimer disease (AD) is the most common neurodegenerative brain disease that causes cognitive impairment in the elderly. Behavioral and psychological symptoms of dementia (BPSD), also known as neuropsychiatric symptoms, represent a heterogeneous group of non-cognitive symptoms and behaviors for AD patients. Sleep disorder is one closely-related psychiatric symptom of AD. In this cross-section study, we aimed to investigate the characteristics of sleep status and BPSD among AD patients in Eastern China and to assess the relationship among sleep disorder, BPSD, and cognition. A total of 176 participants were enrolled in the study, including 84 AD patients and 92 healthy individuals as controls. Mini-mental state examination (MMSE), cooperative study-activities of daily living (ADCS-ADL) and clinical dementia rating (CDR) were used to measure cognition, the competence in basic and instrumental activities of daily living, and severity of dementia, respectively. BPSD were evaluated by neuropsychiatric inventory (NPI). Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale were designed to assess the sleep status and daytime naps. Spearman correlation analyses were performed to determine the relations between PSQI, MMSE, ADCS-ADL, and NPI scores and CDR. Sleep disorders occurred in 55.9% of AD patients versus only 15.2% of controls. 89.2% of AD patients had BPSD while only 22.9% of controls did, with apathy (64.2%) the most common among AD patients. Among AD patients, PSQI was negatively correlated with both MMSE (r=-0.600, P<.01) and ADCS-ADL (r=-0.725, P<.01), and was positively correlated with total NPI score (r=0.608, P<.01). PSQI was closely associated with depression (r=0.653, P<.01) and apathy (r=0.604, P<.01). This study showed that AD patients have a higher prevalence of sleep disorders and BPSD than healthy elderly adults. Sleep disorders affect cognition of AD patients and increase apathy and depression. These results can help investigate new therapeutic targets in AD treatments.