Sleep disturbance in mild cognitive impairment: a systematic review of objective measures

Abstract

Sleep disturbance frequently occurs in patients with mild cognitive impairment (MCI) and appears to be involved in the cellular and molecular mechanisms of cognitive decline. The aim of this systematic review is to clarify whether patients with MCI demonstrate alterations in certain sleep parameters: total sleep time (TST), sleep efficiency (SE), sleep latency (SL), rapid eye movement latency (REML), percent of rapid eye movement (REM%), arousal index (AI), wake after sleep onset (WASO), slow-wave sleep (SWS), periodic leg movement in sleep (PLMS), and cyclic alternating pattern (CAP) through polysomnography (PSG) and actigraphy. Databases including PubMed, Web of Science, Embase, ScienceDirect, Cochrane, CBM, CNKI, Wanfang Data, and VIP were searched up to January 2016 to collect literature on the correlation between sleep disturbance and MCI as assessed by objective measures. Meta-analysis was conducted using the Review Manager 5.3 software. A total of ten case-control studies involving 225 MCI patients and 235 healthy elders (HE) were deemed eligible and included in our meta-analysis. Every type of sleep disturbance was present in our studies with significant differences in the MCI subtypes. Compared with HE, overall MCI patients as a group expressed more SL and less SE; MCI patients showed less TST and SE and more SL and CAP; patients with amnestic mild cognitive impairment (aMCI) had less AI; patients with non-amnestic mild cognitive impairment (naMCI) had more TST and less AI. Patients with naMCI expressed more AI than those with aMCI. The results indicate that MCI patients might experience more serious sleep disturbance and that different MCI subtypes have different patterns of sleep disturbance.

A longitudinal study of polysomnographic variables in patients with mild cognitive impairment converting to Alzheimer's disease

“…Peculiar macrostructural sleep alterations have already been reported in MCI, particularly involving whole sleep parameters, such as total sleep time, whereas REM and N3 sleep reduction appear less consistent (for review, see Hu et al., ). In our study, total sleep time was decreased in both subgroups of patients with aMCI as compared with HE, but inter‐individual variability did not allow reaching statistical significance.…”

Rapid Eye Movement Sleep, Sleep Continuity and Slow Wave Sleep as Predictors of Cognition, Mood, and Subjective Sleep Quality in Healthy Men and Women, Aged 20–84 Years

“…Although experiments demonstrating an impact of insufficient sleep on brain function have been primarily conducted in healthy young participants, studies of sleep in older people indicate that sleep also contributes to brain functioning in the later stages of the life span ( 10 , 17 ). Some studies have reported correlations between sleep and cognition in particular age groups [e.g., ( 18 )] and patient groups such as those with mild cognitive impairment ( 19 ). In these studies age has rarely been treated as a continuous variable and in very few studies has sleep been assessed by polysomnography (PSG) ( 20 , 21 ).…”

Alzheimer's disease and sleep disturbances: a review

“…A meta-analysis of studies comparing objective sleep measures of patients with MCI with those of the healthy elderly showed that the former had shorter total sleep time, sleep efficiency, cycling alternating pattern (a measure of sleep instability) and longer sleep latency. Patients with nonamnestic MCI, on the other hand, had a greater total sleep time compared with the healthy elderly 12 . Other parameters, such as the wake time after sleep onset, slow-wave sleep, REM latency and REM (%), and periodic limb movement syndrome did not differ between the groups 12 .…”

“…Some of its advantages are the low cost for an objective method, the convenience of execution, the low rate of interference in sleep quality and the possibility of mapping the total motor activity of the participant for longer periods, thus being suitable for circadian cycle studies. Also it is appropriate for diagnosing periodic limb movement syndrome 12 .…”

“…They are generated by the thalamus reticularis nucleus neurons and have an association especially with sensorimotor learning, but also with visuospatial and memory functions 20 . Populational EEG studies have revealed that the spectral power in the frequency range of sleep spindles (12)(13)(14)(15)(16) is also reduced in the elderly 13 . Spindle density and amplitude reductions occur mainly in the frontal lobe regions.…”