Prevalence of sleep disturbances in mild cognitive impairment and dementing disorders: a multicenter Italian clinical cross-sectional study on 431 patients

Abstract

Background/aims: Sleep disturbances are common in the elderly and in persons with cognitive decline. The aim of this study was to describe frequency and characteristics of insomnia, excessive daytime sleepiness, sleep-disordered breathing, REM behavior disorder and restless legs syndrome in a large cohort of persons with mild cognitive impairment or dementia.

Methods: 431 consecutive patients were enrolled in 10 Italian neurological centers: 204 had Alzheimer's disease, 138 mild cognitive impairment, 43 vascular dementia, 25 frontotemporal dementia and 21 Lewy body dementia or Parkinson's disease dementia. Sleep disorders were investigated with a battery of standardized questions and questionnaires.

Results: Over 60% of persons had one or more sleep disturbances almost invariably associated one to another without any evident and specific pattern of co-occurrence. Persons with Alzheimer's disease and those with mild cognitive impairment had the same frequency of any sleep disorder. Sleep-disordered breathing was more frequent in vascular dementia. REM behavior disorder was more represented in Lewy body or Parkinson's disease dementia.

Conclusion: A careful clinical evaluation of sleep disorders should be performed routinely in the clinical setting of persons with cognitive decline. Instrumental supports should be used only in selected patients.

Fig. 1

Mean age (years), education (years) and mean scores at MMSE, PSMS, BDI-II and PSQI by MCI and different types of dementia. Vertical lines represent standard deviations. MMSE = Mini-Mental State Examination; PSMS = Physical Self-Maintenance Scale; BDI-II = Beck Depression Inventory-II; PSQI = Pittsburgh Sleep Quality Index; MCI = mild cognitive impairment; AD = Alzheimer's disease; VaD = vascular dementia; FTD = frontotemporal dementia; LBD = Lewy Body dementia; PDD = Parkinson's disease dementia.

Fig. 2

Severity of depressive symptoms (BDI-II), of cognitive (MMSE) and functional (PSMS) impairment and sleep quality (PSQI) by sleep disturbance. MMSE = Mini-Mental State Examination; PSMS = Physical Self-Maintenance Scale; BDI-II = Beck Depression Inventory-II; PSQI = Pittsburgh Sleep Quality Index. Vertical lines represent standard deviations. * p < 0.05.

Fig. 3

Prevalence of insomnia and other sleep disturbances by type of dementia. MCI = Mild cognitive impairment; AD = Alzheimer's disease; VaD = vascular dementia; FTD = frontotemporal dementia; LBD = Lewy Body dementia; PDD = Parkinson's disease dementia; SDB = sleep-disordered breathing; RBD = REM behavior disorder; RLS = restless legs syndrome; EDS = excessive daytime sleepiness.