Sleep disorders after cardiac arrest: Prevalence and relation with cognitive function

Abstract

Background

Long term cognitive impairment affects about half of cardiac arrest survivors, typically attributed to postanoxic encephalopathy. Sleep disorders are common after acute brain injuries and may also impair cognition. We investigated the prevalence of sleep disorders in cardiac arrest survivors and their relation with cognitive function.

Method

Thirty survivors completed neuropsychological examination and questionnaires on mood (Hospital anxiety and depression scale), daytime sleepiness (Epworth sleepiness scale), and sleep quality (Pittsburgh sleep quality index), and underwent polysomnography one year after cardiac arrest. Questionnaire outcomes and objective sleep parameters (sleep-apnea, leg movements, cyclicity) were correlated with performance on neuropsychological tests using Pearson R, Kruskal-Wallis, or Mann-Whitney U tests.

Results

Thirty-six percent of participants had moderate to severe obstructive sleep apnea, and 43% moderate to severe periodic limb movements during sleep according to polysomnography. Obstructive sleep apnea was correlated with poorer executive functioning (R = −0.38; p < 0.05) and memory (R = −0.50; p < 0.05). Fewer sleep cycles were correlated with poorer attention (R = 0.36, p = 0.05). Questionnaire outcomes (mood, daytime sleepiness, sleep quality) were not related to cognition. Participants with moderate/severe obstructive sleep apnea had worse executive functioning than those with no/mild obstructive sleep apnea (p = 0.02).

Conclusion

This explorative study shows moderate to severe sleep disorders are common in cardiac arrest survivors and that moderate to severe obstructive sleep apnea relates to poorer cognitive function. This implies that diagnosis and treatment of obstructive sleep apnea may offer a treatment target for cardiac arrest survivors with cognitive impairment.