Higher Frequency and Complexity of Sleep Disturbances in Dementia with Lewy Bodies as Compared to Alzheimer's Disease

Background: Sleep disturbances (SDs) are common in patients with all forms of dementia. However, most studies focus on Alzheimer's disease (AD) and less is known about the prevalence and characteristics of SD in dementia with Lewy bodies (DLB). Objective: The aims of this cross-sectional study were: (1) to examine the frequency of SD in DLB versus AD; (2) to compare patients with and without SD with regard to relevant clinical variables, and (3) to investigate the associations between SD and medication use. Methods: Patients with a first-time diagnosis of probable or possible DLB or AD were selected from the Dementia Study of Western Norway and recruited from clinics for old age psychiatry from 2010 until the end of 2013. Results: In all, 123 (55.7%) subjects with dementia suffered from at least one SD. Insomnia was present in 77 (34.8%), and 34 (20.7%) patients had probable REM-sleep behaviour disorder (RBD). All SDs were also significantly more frequent in patients with DLB than in AD, and DLB patients also more often had several co-occurring SDs. The presence of any SD was associated with more neuropsychiatric symptoms, higher morbidity, more parkinsonian symptoms and excessive daytime sleepiness. Antiparkinsonian medication was used more often in RBD, restless leg syndrome (RLS) and periodic limb movements, and benzodiazepines were also common in RLS. Conclusions: Sleep problems are more common in DLB patients compared to AD, and are associated with more clinical impairment. DLB patients frequently have several sleep problems occurring simultaneously, which suggests a need for screening and accurate assessment of sleep in DLB.