Among patients with minor ischemic stroke, obstructive sleep apnea (OSA) has a significant negative effect on comprehension and perception, according to study findings published recently in Sleep and Breathing.
Worldwide, stroke is a leading causes of death and long-term disability. Not much is known about the connection between cognitive impairment and OSA, which is often seen in patients with stroke. Researchers therefore sought to investigate the relationship between OSA and cognitive impairment in patients with minor ischemic stroke.
To achieve this goal, they conducted a cross-sectional study of 94 patients (aged 18 to 75 years) admitted to the Neural Psychiatric Disorders and Mental Health Center of Anhui Province, China, within 7 days of onset of their first ischemia stroke, between January 2020 and May 2021. All patients were tested overnight for OSA with polysomnography, assessed for severity using the apnea hypopnea index (AHI), and divided into the following categories: no OSA (AHI <5; 35 patients representing the control group; 57.6±10.3 years of age; 74% male); mild OSA (AHI 5 to 14; 32 patients; 55.9±6.8 years of age; 69% male), and moderate-to-severe OSA (AHI ≥15; 27 patients; 55.8±8.0 years of age; 67% male).
Self-evaluation questionnaires revealed no noticeable differences between cohorts for daytime sleepiness. Multiple tests were administered to assess cognitive function, and researchers examined the correlation between cognitive function and OSA. More than three-fourths of the moderate to severe OSA cohort had been previously diagnosed with hypertension, half again as many patients as in each of the other 2 cohorts.
Of the 3 groups, the moderate to severe OSA cohort performed the worst on classical tests: the Chinese version of the Auditory Verbal Learning Test (CAVLT)-Recognition, Digital Span Test (DST)-Backward, Montreal Cognitive Assessment (MoCA), and Stroop Color and Word Test (SCWT)-Interference (all P <.001). The MoCA (most comprehensive of the tests administered) measured the severity of cognitive impairment, which was found to be negatively related to the AHI (P =.041) and to lowest oxygen saturation (P =.048).
“Findings of this study suggest that OSA contributes to the cognitive impairment in patients with minor ischemic stroke. The data further suggest that hypoxemia may underline pathological and OSA-triggered cognition impairment,” the researchers concluded. Study limitations included the cross-sectional research design which prevents causal inference, the small sample size, and the deviations in the number of patients reporting hypertension and smoking which may have affected cohort comparisons.
Zhu RL, Ouyang C, Ma RL, Wang K. Obstructive sleep apnea is associated with cognitive impairment in minor ischemic stroke. Sleep Breath. Published online March 19, 2022. doi:10.1007/s11325-022-02575-5