Sleep Apnea Impacts Cognition in Patients Recovering From Traumatic Brain Injury

During the early stages of recovery from a traumatic brain injury (TBI), obstructive sleep apnea (OSA) is highly common, with mild cases of the disorder associated with poorer cognitive performance, according to study findings published in the journal Sleep Medicine.

The current cross-sectional, secondary analysis leveraged data from a clinical trial, Comparison of Sleep Apnea Assessment Strategies to Maximize TBI Rehabilitation Participation and Outcome (C-SAS; ClinicalTrials.gov Identifier: NCT03033901) and TBI Model Systems. Researchers sought to explore the relationship between polysomnography-classified OSA severity and cognitive performance in participants who had experienced an acute moderate to severe TBI.

A total of 60 participants were enrolled in the study. The mean age for patients was 50.0±18.1 years. Overall, 71.7% of the patients were men and 66.7% were White. In all, 76.7% (46 of 60) of the participants fulfilled the criteria for OSA (19 with mild OSA, 11 with moderate OSA, and 16 with severe OSA). All of the participants with TBI from 1 of 5 different civilian rehabilitation hospitals were evaluated at 1 month post-TBI.

The patients all underwent Level 1 polysomnography. The Apnea-Hypopnea Index (AHI) was used to classify OSA as mild, moderate, or severe. Additionally, associations between OSA metrics of hypoxemia (ie, nadir and total time spent with oxygen saturation below 90%) and AHI with cognition were assessed. The Brief Test of Adult Cognition by Telephone (BTACT) was utilized to evaluate cognition, which included 6 subtests.

The researchers found that AHI had a statistically significant and negative relationship with Immediate Word Recall (P =.036) and Number Series (P =.028). Further, nadir had a statistically significant relationship with Number Series (P =.044). Participants with mild OSA exhibited worse working memory and executive function than those with moderate or severe OSA.

The total sleep time spent with oxygen saturation below 90% was not statistically significantly associated with any cognitive outcome. Although other significant predictors emerged, including age, education, and time since injury, the results were inconsistent across the subtests.

Several study limitations should be noted, including the small convenience sample and the dichotomization of OSA without any regard for disease severity. The wide variability in the time following TBI was a limitation as well — 94.3±152.1 months postinjury —which can significantly affect an individual’s cognitive performance.

According to the researchers, “Our results support the incorporation of OSA diagnostic tools and interventions into routine clinical care in rehabilitation settings. . . . OSA as a treatable disease represents a treatment target that has the potential to modify cognitive morbidity after TBI.”

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.