Overnight declarative memory consolidation and non-rapid eye movement sleep electroencephalographic oscillations in older adults with obstructive sleep apnea

Jun Z Teh; Lucinda Grummitt; Carla Haroutonian; Nathan E Cross; Bradley Skinner; Delwyn J Bartlett; Brendon Yee; Ronald R Grunstein; Sharon L Naismith; Angela L D'Rozario

doi:10.1093/sleep/zsad087

Overnight declarative memory consolidation and non-rapid eye movement sleep electroencephalographic oscillations in older adults with obstructive sleep apnea

Sleep. 2023 Jun 13;46(6):zsad087. doi: 10.1093/sleep/zsad087.

Authors

Jun Z Teh^{1

2

3}, Lucinda Grummitt¹, Carla Haroutonian^{1

2}, Nathan E Cross², Bradley Skinner², Delwyn J Bartlett^{2

3}, Brendon Yee^{2

4

5}, Ronald R Grunstein^{2

3

4

5}, Sharon L Naismith^{1

3}, Angela L D'Rozario^{1

2

3

6}

Affiliations

¹ School of Psychology, Faculty of Science, Brain and Mind Centre and Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia.
² CIRUS Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, Macquarie University, Sydney, NSW, Australia.
³ NHMRC Centre of Research Excellence to Optimise Sleep in Brain Ageing and Neurodegeneration (CogSleep CRE), Sydney, NSW, Australia.
⁴ Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.
⁵ Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, Camperdown, Sydney, NSW, Australia.
⁶ School of Psychological Sciences, Macquarie University, Sydney, NSW, Australia.

Abstract

Study objectives: To compare overnight declarative memory consolidation and non-rapid eye movement (NREM) sleep electroencephalogram (EEG) oscillations in older adults with obstructive sleep apnea (OSA) to a control group and assess slow-wave activity (SWA) and sleep spindles as correlates of memory consolidation.

Methods: Forty-six older adults (24 without OSA and 22 with OSA) completed a word-pair associate's declarative memory task before and after polysomnography. Recall and recognition were expressed as a percentage of the morning relative to evening scores. Power spectral analysis was performed on EEG recorded at frontal (F3-M2, F4-M1) and central (C3-M2, C4-M1) sites. We calculated NREM absolute slow oscillation (0.25-1 Hz) and delta (0.5-4.5 Hz) EEG power, and slow (11-13 Hz) spindle density (number of events per minute of N2 sleep) and fast (13-16 Hz) spindle density.

Results: There were no significant differences in overnight recall and recognition between OSA (mean age 58.7 ± 7.1 years, apnea-hypopnea index (AHI) 41.9 ± 29.7 events/hour) and non-OSA (age 61.1 ± 10.3 years, AHI 6.6 ± 4.2 events/hour) groups. The OSA group had lower fast spindle density in the frontal region (p = 0.007). No between-group differences in SWA were observed. In the Control group, overnight recognition positively correlated with slow spindle density in frontal (rho = 0.555, p = 0.020) and central regions (rho = 0.490, p = 0.046). Overnight recall was not related to SWA or spindle measures in either group.

Conclusions: Older adults with OSA had deficits in fast sleep spindles but showed preserved overnight declarative memory consolidation. It is possible that compensatory mechanisms are being recruited by OSA patients to preserve declarative memory consolidation despite the presence of sleep spindle deficits.

Keywords: EEG power spectra; Sleep-disordered breathing; cognition; electroencephalography; learning.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Electroencephalography
Eye Movements
Humans
Memory Consolidation*
Middle Aged
Sleep
Sleep Apnea, Obstructive*