Sleep-Wake Profile in Dementia with Lewy Bodies, Alzheimer's Disease, and Normal Aging

Alterations of the sleep-wake cycle are common features of neurodegenerative dementia.

To study differences in sleep-wake profiles in dementia with Lewy bodies (DLB), Alzheimer's disease (AD), and healthy controls.

30 DLB and 32 AD patients, and 33 healthy elderly participants were studied. Patients were evaluated for global cognitive impairment, extrapyramidal signs, fluctuations of attention, and behavioral disorders. A comprehensive sleep-wake profile was obtained including a set of questionnaires [Pittsburgh Sleep Quality Index (PSQI), REM Sleep Behavior Disorder Single-Question screen (RBD1Q), Epworth Sleepiness Scale (ESS)] and 12-day sleep diaries.

Patients were matched for age, gender, and disease severity. DLB patients showed more severe daytime somnolence/dysfunction due to somnolence, and a higher proportion of RBD-like symptoms (70%) compared to AD and controls (p < 0.001), regardless of the presence of psychoactive drug treatment. As for sleep timing, DLB patients had a greater number of daytime naps and longer night sleep, with the latter being associated with use of clonazepam. The severity of fluctuations was associated with the presence of RBD (Clinician Assessment of Fluctuation score = RBD+: 5.2±3.7; RBD-: 2.1±3.2, p = 0.04). AD patients reported the best sleep-wake profile, while healthy controls declared the poorest sleep quality, although sleep timing and the quality of wakefulness were comparable between AD and controls.

RBD and daytime fluctuations of attention may coexist in DLB and even reciprocally potentiate each other. Self-reports of sleep quality may lead to an underestimation of sleep disturbances in AD, possibly influenced by anosognosia, compared to normal elderly individuals who complain mainly of insomnia.