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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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.

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).

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


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