Objective: Sleep disturbances were found to be associated with more behavioral and psychological symptoms (BPS) in early patients with Alzheimer's disease (AD). However, data on preclinical stages of dementia are lacking. Hence, the present study sought to investigate the association between sleep disturbances and BPS in dementia-free elderly with varying severity of cognitive impairment in an Asian sample.
Methods: Community-living elderly were recruited and administered a comprehensive cognitive battery (vascular dementia battery [VDB]) and the Neuropsychiatric Inventory to assess symptoms of sleep disturbances and BPS. Severity of cognitive impairment was diagnosed and classified as no cognitive impairment (NCI), cognitive impairment-no dementia (CIND) -mild (1-2 impaired domains on the VDB), and CIND-moderate (≥3 impaired domains on the VDB). Analysis of variance was conducted to assess the associations between the presence of sleep disturbances and BPS scores in each diagnostic group. Logistic regression was used to examine whether the coexistence of sleep disturbances and other BPS was associated with CIND-moderate, which is known to carry a higher risk of progression to AD.
Results: Among 839 elderly, 79 (9.4%) reported sleep disturbances. Participants with sleep disturbances had higher total BPS burden than those without among CIND participants but not in NCIs. Furthermore, CIND-moderate participants with sleep disturbances had more delusions, hallucinations, anxiety, depression, irritability, aberrant motor behavior, and appetite change ( P < .05). The presence of both sleep disturbances and other BPS was associated with CIND-moderate (odds ratio: 2.5, 95% confidence interval: 1.1-5.5).
Conclusions: Sleep disturbances are associated with higher total BPS burden and specific BPS among elderly patients with cognitive impairment, particularly those with CIND moderate, which carries higher risk of developing dementia.
Keywords: behavioral and psychological symptoms; cognitive impairment-no dementia; sleep disturbances.