Procedural learning worsens with OSA severity in older adults and is insensitive to short exposure supplemental oxygen therapy

Abstract

Study objectives: Obstructive sleep apnea (OSA) has been associated with cognitive deficiencies in young and middle aged adults but the impact on cognition in older adults, who are at greater risk of age-related cognitive decline, is less well understood. We investigated how OSA severity impacts cognitive performance in older adults and whether short exposure to supplemental oxygen can modify this relationship, whilst also leveraging pathophysiology to identify oxygen treatment candidates.

Methods: 65 participants (65+ years) not currently receiving OSA treatment were recruited from the San Diego community, most of whom presented with moderate or severe OSA. Participants undertook two nights of in-laboratory polysomnography under room air or nocturnal oxygen supplementation (NOS) conditions in randomized order. Participants performed sleep-dependent cognitive tests both before and after sleep.

Results: Nocturnal hypoxemia was reduced with NOS treatment. There was no reduction in the frequency of apnea-hypopnea events (AHI) in the full sample, however we found a significant treatment effect on AHI among participants with OSA severity >15 events/hour or among those with below-median pharyngeal collapsibility. Motor sequence task improvement was negatively correlated with AHI within a night but NOS treatment did not improve performance between nights in either the full sample or a responsive sub-group.

Conclusions: As in younger adults, more severe sleep apnea is associated with worse motor procedural learning in older adults. However, a single night of NOS treatment had no effect on procedural learning, suggesting that OSA-related cognitive deficits result from chronic impacts of sleep disruption and hypoxia.

Keywords: Cognition; Endotypes; Learning; Sleep apnea; Supplemental oxygen.

Fig. 1.

Generalized estimation equation model estimated at apnea-hypopnea index value in the range 0–90. Shading depicts linear regression 95 % confidence intervals. MST = motor sequence task. AHI = apnea-hypopnea index in non-rapid eye movement sleep. Ox = nocturnal oxygen supplementation.