Sleep-Wake Patterns and Cognition of Older Adults with Amnestic Mild Cognitive Impairment (aMCI): A Comparison with Cognitively Healthy Adults and Moderate Alzheimer’s Disease Patients

Abstract

This investigation is of clinical importance, because major confounding variables were excluded. The lack of comorbidities might be responsible for the absence of sundown syndrome and sleep disturbances commonly reported in AD patients. Whether there is interdependence between progressive decline in cognition and long sleep duration remains elusive. Future studies should address whether prolonged sleep at night and decreased day-time activity can be altered to delay the progression of cognitive decline.

24-h Activity Rhythms and Health in Older Adults

“…Research increasingly focuses on the pre-diagnostic phase of dementia to investigate the potential etiological or predictive role that 24-h activity rhythm disturbances may have in dementia. Two recent studies investigated persons with potential prodromal symptoms of dementia, but no evidence was found for an association of phase with subjective cognitive complaints [35] or of amplitude with mild cognitive impairment [30]. This was even though the latter was found to be disturbed in those with Alzheimer's disease [30].…”

“…These disruptions predominantly include fragmentation and a reduced amplitude of the 24-h activity rhythm, and behaviors such as "sun-downing" [27] and frequent daytime napping [28]. Recent cross-sectional studies report a lower amplitude [28][29][30], a lower stability [29,31], and more fragmentation [29] in patients with dementia. More fragmented 24-h activity rhythms were also found in persons with earlyonset dementia [32].…”

“…Two recent studies investigated persons with potential prodromal symptoms of dementia, but no evidence was found for an association of phase with subjective cognitive complaints [35] or of amplitude with mild cognitive impairment [30]. This was even though the latter was found to be disturbed in those with Alzheimer's disease [30]. In contrast, some earlier studies have reported a phase advance in persons with mild cognitive impairment compared with healthy controls [36,37] and a higher fragmentation and lower mesor in those with preclinical AD [16].…”

Characteristics of Sleep Structure Assessed by Objective Measurements in Patients With Amnestic Mild Cognitive Impairment: A Meta-Analysis

“…TST Six (22,24,(26)(27)(28)(29) included studies showed that there was no significant difference between the aMCI and NC groups (SMD = −0.51, 95%CI (−2.10∼1.08), P = 0.53) ( Figure 2).…”

“…Information of the eight included studies (22)(23)(24)(25)(26)(27)(28)(29), such as publication time, countries, major criteria of aMCI, and characteristics of the aMCI and control samples are listed ( Table 2).…”