Sleep disturbance in mild cognitive impairment: a systematic
review of objective measures
Yo ngfe i Ta n
Received: 21 November 2016 /Accepted: 19 April 2017 /Published online: 28 April 2017
Springer-Verlag Italia 2017
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 move-
ment in sleep (PLMS), and cyclic alternating pattern (CAP)
through polysomnography (PSG) and actigraphy. Databases
including PubMed, Web of Science, Embase, ScienceDirect,
searched up to January 2016 to collect literature on the corre-
lation between sleep disturbance and MCI as assessed by ob-
jective 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 impair-
ment (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 sub-
types have different patterns of sleep disturbance.
Keywords Mild cognitive impairment
In the World Alzheimer Report 2015, it is said that there are
over 9.9 million new cases of dementia each year worldwide,
implying one new case every 3.2 s . Mild cognitive impair-
ment (MCI) is viewed as a transitional stage from normal
health to dementia [2, 3], with a conversion rate of
60.5~100% to dementia in 5~10 years . Given the limita-
tions of therapeutic methods for dementia, an understanding
of the clinical features of MCI is crucial for the development
of preventive projects and early interventions.
Previous and recent studies all show that sleep disturbance
is one of the major causes of MCI [3, 4]. Researchers are also
investigating early predictors of MCI and have identified all
kinds of markers [5–8], and plenty of findings have suggested
that sleep disturbance is a risk factor of MCI or that MCI
patients experienced a more serious degree of sleep distur-
bance than healthy elders (HE) [2, 7, 8].
Sleep disturbance can be evaluated by subjective and ob-
jective measures . For objective measures, medical detect-
ing and monitoring equipment has been widely used.
Actigraphy is highly correlated with polysomnography
(PSG) for detecting sleep states [8, 9]. The present review
includes a variety of results regarding the use of PSG and
actigraphy methods to evaluate sleep disturbance [10–12].
Mingyue Hu and Ping Zhang contributed equally to this work.
* Li Chen
College of Nursing, Jilin University, 965 Xinjiang Road,
Changchun 130021, China
Department of Pharmacology, College of Basic Medical Sciences,
Jilin University, Changchun, China
Neurol Sci (2017) 38:1363–1371