Integrity of Multiple Memory Systems in Individuals With Untreated Obstructive Sleep Apnea

Chris Tailby,Genevieve Rayner,Fergal J. O’Donoghue,Melinda L. Jackson,Graeme D. Jackson,Lucy Sommers,Rachel Schembri,Sarah Wilson

doi:10.3389/fnins.2020.00580

Abstract

Obstructive sleep apnea (OSA) is associated with working- and autobiographical-memory impairments, and high rates of mood disorder. This study aimed to examine (i) behavioral responses and (ii) neural activation patterns elicited by autobiographical and working memory tasks in moderate-severe untreated OSA patients and healthy controls, and (iii) whether variability in autobiographical and working memory activation are associated with task performance, OSA severity and psychological symptomatology (depression, anxiety). In order to control for the potential confounding effect of elevated rates of clinical depression in OSA, we excluded individuals with a current psychiatric condition. Seventeen untreated OSA participants and 16 healthy controls were comparable with regards to both activation and behavioral performance. OSA was associated with worse subclinical mood symptoms and poorer personal semantic memory. Higher levels of nocturnal hypoxia were associated with increased activation in the occipital cortex and right cerebellum during the working memory task in OSA participants, however, no significant relationships between activation and task performance or depressive/anxiety symptomatology were observed. The neurocognitive substrates supporting autobiographical recall of recent events and working memory in younger, recently diagnosed individuals with OSA appear to be indistinguishable from healthy age-matched individuals. These findings point to the importance of early diagnosis and treatment of OSA in order to preserve cognitive function.

Highlights

Obstructive Sleep Apnea (OSA) is a common sleep disorder, caused by collapse of the pharyngeal airway during sleep producing intermittent hypoxia, frequent arousals from sleep, and fragmented sleep patterns (Young et al, 2002)
Healthy control participants were recruited through (1) advertising flyers posted at Austin Health, and (2) healthy family members recruited from an fMRI study of autobiographic memory in epilepsy (Tailby et al, 2017)
While the groups overlapped in age, there was a significantly greater proportion of males in the Obstructive sleep apnea (OSA) group

Summary

Introduction

Obstructive Sleep Apnea (OSA) is a common sleep disorder, caused by collapse of the pharyngeal airway during sleep producing intermittent hypoxia, frequent arousals from sleep, and fragmented sleep patterns (Young et al, 2002). OSA is associated with changes in brain morphology (Morrell et al, 2010) and brain network activity, both of which are associated with cognitive impairments (Canessa et al, 2011) Impairments of both the working memory and autobiographical memory systems have been reported in OSA. We recently reported significant impairments in the ability of OSA patients to recall specific autobiographical events (Lee et al, 2016), and to retrieve personal semantic information (Delhikar et al, 2019) compared to healthy controls. Such impairments are linked to significant reductions in productivity, mood, and quality of life (Sumner et al, 2010)

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