Impaired sleep-dependent memory consolidation in pediatric narcolepsy type 1

Abstract

Study Objectives: Disrupted nighttime sleep is common in pediatric narcolepsy type 1, yet its cognitive impact is unknown. As N2 sleep spindles are necessary for sleep-dependent memory consolidation, we hypothesized that narcolepsy type 1 impairs memory consolidation via N2 sleep fragmentation and N2 sleep spindle alterations. Methods: We trained 28 pediatric narcolepsy type 1 participants and 27 healthy controls (HCs) on a spatial declarative memory task before a nocturnal in-lab polysomnogram and then gave them a cued recall test upon awakening in the morning. We extracted wake and sleep stage bout numbers and N2 spindle characteristics from the polysomnogram and conducted mixed model analysis of sleep-dependent memory consolidation to identify group differences. Results: Narcolepsy type 1 participants had shorter N2 bout durations and associated shorter N2 spindles versus HC, but other N2 spindle features were similar. Narcolepsy type 1 participants had worse memory performance postsleep than HCs after adjusting for age and gender (mean memory consolidation HC: −3.1% ± 18.7, NT1: −15.6 ± 24.8, main effect group × time of testing F = 5.3, p = .03). We did not find significant relationships between sleep-dependent memory consolidation and N2 spindle characteristics. Notably, increased N1% was associated with worse sleep-dependent memory consolidation with results driven by the narcolepsy type 1 group. Conclusions: Sleep-dependent memory consolidation is mildly impaired in youth with narcolepsy type 1 and findings may be attributed to increases in N1 sleep. Further studies are needed to determine if these findings are generalizable and reversible with sleep-based therapies.