Effects of cholinergic medication on EEG delta and theta activity during REM sleep in old age: implications for sleep-related memory consolidation

Abstract

Research suggests that REM sleep theta and delta oscillations as well as phasic components may play an important role in memory consolidation. REM sleep increases following administration of an AChE-I were found to be associated with improved memory consolidation in older adults. Whether such benefits may also be associated with higher EEG theta and delta activity during REM sleep was investigated. Forty-two participants (mean age=65.4±4.6, 57% female) received 5mg of the AChE-I donepezil in a placebo-controlled, double-blind design. Mean root mean square (RMS) voltages in EEG delta (1–4 Hz) and theta (4–8 Hz) frequency bands were calculated for total and phasic REM sleep as well as total sleep time. As reported earlier, participants of the medication group showed significant benefits in sleep-related memory consolidation (p<.05). A trend for higher mean delta RMS voltages in the medication group was found for total REM sleep (p<.10), this effect being more pronounced for phasic REM sleep (p<.05). The groups did not differ in mean delta RMS voltages of total sleep time. No significant effects were found for mean theta RMS voltages. Hence, the AChE-I donepezil seems to enhance EEG delta activity during phasic REM sleep in old age, which may partly explain its beneficial effects on sleep-related memory consolidation in older adults.