The impact of APOE-ε4 status on sleep, rest-activity patterns and spatial navigation in healthy adults

Michalak, Adriana (2022) The impact of APOE-ε4 status on sleep, rest-activity patterns and spatial navigation in healthy adults. Doctoral thesis, University of East Anglia.

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Abstract

INTRODUCTION
Alzheimer's disease(AD) is the most common type of dementia manifesting mainly over the age of 65 with no curative treatment available. The risk of AD is increased in APOE-ɛ4 allele carriers and those with sleep and circadian disturbances. APOE-ε4 polymorphism was also shown to be associated with spatial navigation impairment, which has been proposed to serve as a potential early marker of AD. Yet, the interrelationships between APOE-ɛ4 carriership, sleep, rest-activity patterns and spatial navigation in healthy older adults are still unclear. The presented PhD project addresses this research gap.

METHODS
One-hundred-sixty-one healthy participants took part in extensive screening sessions (51 APOE-ε4+, age(M+SD)=63.18+7.84; 110 APOE-ε4-, age(M+SD)=65.66+9.98) of which fifty-eight (28 APOE-ε4+, age(M+SD)=64.45+7.36; 30 APOE-ε4-, age(M+SD)=65.23+10.34) participated in a 14-days-long actigraphy session supplemented by sleep diary. Thirty-five individuals (18 APOE-ε4+, age(M+SD)=64.21+8.58; 17 APOE-ε4-, age(M+SD)=65.00+9.54) underwent a 2.5-days-long laboratory session in dim light condition(<10lux) and followed a modified constant routine protocol in the Sleep and Brain Research Unit. After a baseline night, participants were randomly assigned to either a 40-h sleep deprivation(SD) or a multi-nap(MN) experimental condition followed by a recovery night. Cognitive assessments were administered every 4-hours. Nine 80-minute-long naps were scheduled every 160 minutes(MN condition).

RESULTS and DISCUSSION
Our results suggest that APOE-ɛ4 carriership in healthy elderly adults has a limited impact on subjective and objective sleep quality, daytime sleepiness and circadian rhythmicity measures besides a decrease in circadian rest-activity amplitude and a marginal decrease in the percentage of Total-Sleep-Time spent in N2 at baseline night. Yet, recovery sleep revealed an altered physiological recovery process in APOE-ɛ4 allele carriers that was reflected as a low percentage of deep sleep following SD protocol. Further, the outcomes suggest that spatial navigation performance is modulated neither by time-of-a-day nor is affected by increasing sleep pressure or by their associations with APOE-ɛ4 carriership.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Medicine and Health Sciences > School of Health Sciences
Depositing User:	Chris White
Date Deposited:	26 Apr 2023 08:49
Last Modified:	26 Apr 2023 08:49
URI:	https://ueaeprints.uea.ac.uk/id/eprint/91885
DOI:

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