0094 The Effect of Zolpidem on Sleep-Dependent Declarative Memory Consolidation

Abstract

Abstract Introduction Sleep plays a critical role in memory consolidation. At the same time, about 20% of population in the U.S. suffer from sleep disorders or deprivation, and about 16% of them reported using sleep aids (CDC, 2015). However, the effect of sleep aids on sleep-dependent memory consolidation remains unclear. Previous studies have observed an improvement in sleep-dependent declarative memory consolidation with zolpidem over a daytime nap (Mednick et al., 2013). The current study investigates the effect of zolpidem on declarative memory consolidation over a night of sleep and over 24 hours. Methods This study employed a double-blind, placebo-controlled, within-subject design, in which every subject (N=26, 12 females) experienced both zolpidem and placebo. All subjects were healthy, college-aged adults without sleep disorder. A 32-channel electroencephalogram cap was used to record brain activity during sleep. Word paired-associates task was used to evaluate memory performance. Participants reported to the laboratory in the evening, performed word paired-associates task (test1), then ingested either zolpidem or placebo before sleep. They were tested on the task in the following morning (test2) as well as in the following evening (test3). Paired-sample t-tests for retrieval difference scores between placebo and zolpidem conditions were conducted. Results Participants showed similar baseline performance on the word paired-associates task (test 1, p=0.45). Zolpidem condition showed higher memory retention compared to placebo 24hr after drug ingestion (test3-test1, t₂ 5=2.09, p<0.05). The improvement in performance for zolpidem condition occurred across the following day (test3-test2, t₂ 5=2.22, p<0.05), as no difference was observed between conditions after sleep (test2-test1, t₂ 5=0.34, p=0.74) Conclusion Consistent with previous studies, participants showed better memory performance after taking zolpidem compared to placebo. However, the current study showed that the improvement in memory occurred across a day of wakefulness after nighttime drug ingestion, while other studies observed improvements shortly after sleep, indicating a potential delayed benefit of zolpidem on memory consolidation. Support This work was supported by the Office of Naval Research grant N00014-14-1-0513