Different profiles of sleep disturbances in early-stage neurocognitive diseases: a prospective cohort study

Background Alzheimer’sdisease (AD), behavioral variant frontotemporal dementia bvFTD, and dementia with Lewy bodies (DLB) are all associated with sleep disturbances; however, reports on the prevalence of sleep disorders or symptoms in the early stages of these diseases are limited. Our goal was to assess the prevalence of sleep disturbances and characterize different sleep disturbance profiles in early-stage AD, bvFTD and DLB. Methods A total of 111 early-stage patients including 60 AD (mean age 64.3), 35 bvFTD (mean age 62.4), and 16 DLB cases (mean age 71.1), along with 63 cognitively healthy controls (HC, mean age 59.0), were prospectively recruited from Kuopio and Oulu University Hospitals. Early-stage was determined by Clinical Dementia Rating Scale (CDR) global score 0–1. Sleep disturbances were evaluated using the Basic Nordic Sleep Questionnaire (BNSQ), focusing on characterization of prior sleep habits, sleep disorders, and sleep-related (hypnotic) drug usage. Results DLB patients showed the highest overall burden of sleep disturbances relative to other groups. When bvFTD was compared to AD, patients with bvFTD reported more apneas during sleep than AD (18% % vs. 4%, p = 0.024, OR = 0.17, 95% Cl 0.03–0.92). When compared to HC, patients with bvFTD exhibited fewer nighttime awakenings (44% vs. 71%, p = 0.003, OR = 0.22, 95% CI 0.08–0.59) and reported about one hour more sleep per day (8.46 h vs. 7.59 h, General linear model, p = 0.020, B = -0.70), similar to findings in AD (8.40 h vs. General linear model, 7.59 h, p = 0.001, B = -0.78). No significant differences in total sleep duration were observed between disease groups. Conclusions Sleep disturbance profiles differed across disease groups at an early stage, but when compared to HC differences were modest. These findings suggest sleep disturbances may be present in early disease stage.