Research Letter: Impact of Obstructive Sleep Apnea Disease Duration on Neuropsychological Functioning After Traumatic Brain Injury: A Veterans Affairs TBI Model Systems Study

Obstructive sleep apnea and polysomnographic predictors of neuropsychological performance two years after injury in a prospective cohort of adults with traumatic brain injury

Objective: Obstructive sleep apnea (OSA) has been associated with structural and functional brain changes and cognitive impairment in sleep clinic samples. Persons with traumatic brain injury (TBI) are at increased risk of OSA compared to community samples, and many experience chronic cognitive disability. However, the impact of OSA on cognitive outcome after TBI is unknown. The purpose of this study was to examine the relationship between polysomnographic sleep parameters on neuropsychological performance 2 years following TBI. We hypothesized that oxygen desaturation, sleep fragmentation, and sleep depth would predict neuropsychological performance. Method: Participants (N = 123) were persons with moderate-to-severe TBI who underwent Type 1 Polysomnography during acute neurorehabilitation. At 2 years post-TBI, participants completed telephone-based neuropsychological testing (the Brief Test of Adult Cognition by Telephone). General linear models were fit to investigate the relationship between sleep parameters and neuropsychological performance, controlling for demographics and posttraumatic amnesia. Results: When controlling for demographics, injury characteristics, and other sleep parameters, greater percent of Stage 1 sleep time predicted poorer cognitive performance (Overall BTACT composite, p = 0.0078, ηp2 = 6.6%; Verbal Memory composite, p = 0.0407, ηp2 = 3.9%; Executive Function composite, p = 0.0215, ηp2 = 4.9%). Oxygen desaturation, cortical arousals, Stage 3 sleep, and the obstructive apnea-hypopnea index were not significantly associated with cognitive outcome. Conclusions: Reduced sleep depth was associated with cognitive outcome in persons with TBI; these findings require replication. Future research should examine whether improving sleep (e.g. increasing deep sleep) during acute recovery can improve cognitive recovery following TBI.

Cost-Effectiveness of Sleep Apnea Diagnosis and Treatment in Hospitalized Persons With Moderate to Severe Traumatic Brain Injury

OBJECTIVE

To assess the cost-effectiveness of alternative approaches to diagnose and treat obstructive sleep apnea (OSA) in patients with traumatic brain injury (TBI) during inpatient rehabilitation.

SETTING

Data collected during the Comparison of Sleep Apnea Assessment Strategies to Maximize TBI Rehabilitation Participation and Outcome (C-SAS) clinical trial (NCT03033901) on an inpatient rehabilitation TBI cohort were used in this study.

STUDY DESIGN

Decision tree analysis was used to determine the cost-effectiveness of approaches to diagnosing and treating sleep apnea. Costs were determined using 2021 Centers for Medicare and Medicaid Services reimbursement codes. Effectiveness was defined in terms of the appropriateness of treatment. Costs averted were extracted from the literature. A sensitivity analysis was performed to account for uncertainty. Analyses were performed for all severity levels of OSA and a subgroup of those with moderate to severe OSA. Six inpatient approaches using various phases of screening, testing, and treatment that conform to usual care or guideline-endorsed interventions were evaluated: (1) usual care; (2) portable diagnostic testing followed by laboratory-quality testing; (3) screening with the snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender (STOP-Bang) questionnaire; (4) Multivariable Apnea Prediction Index (MAPI) followed by portable diagnostic testing and laboratory-quality testing; (5) laboratory-quality testing for all; and (6) treatment for all patients.

MAIN MEASURES

Cost, Effectiveness, and Incremental Cost-Effectiveness Ratio (ICER).

RESULTS

Phased approaches utilizing screening and diagnostic tools were more effective in diagnosing and allocating treatment for OSA than all alternatives in patients with mild to severe and moderate to severe OSA. Usual care was more costly and less effective than all other approaches for mild to severe and moderate to severe OSA.

CONCLUSIONS

Diagnosing and treating OSA in patients with TBI is a cost-effective strategy when compared with usual care.

Detecting and Predicting Cognitive Decline in Individuals with Traumatic Brain Injury: A Longitudinal Telephone-Based Study

Traumatic brain injuries (TBIs) can lead to long-lasting cognitive impairments, and some survivors experience cognitive decline post-recovery. Early detection of decline is important for care planning, and understanding risk factors for decline can elucidate targets for prevention. While neuropsychological testing is the gold standard approach to characterizing cognitive function, there is a need for brief, scalable tools that are capable of detecting clinically significant changes in post-TBI cognition. This study examines whether a clinically significant change can be detected using the Brief Test of Adult Cognition by Telephone (BTACT) in a sample of individuals with chronic TBI and investigates whether potentially modifiable factors are associated with cognitive decline. Ninety participants aged 40 or older with complicated mild-to-severe TBI participated in two telephone-based study visits ∼1 year apart. Demographic, head trauma exposure, comorbid medical conditions, physical, and psychosocial functioning data were collected via self-report. The BTACT, a brief measure of global cognitive function, was used to assess cognitive performance across six domains. A reliable change index for quantifying clinically significant changes in BTACT performance was calculated. Results revealed cognitive decline in 10-27% of participants across various cognitive domains. More specifically, only depressive symptoms, including depressed affect and anhedonia, were significantly associated with cognitive decline after correcting for multiple comparisons using false discovery rate (FDR). Other factors such as the number of blows to the head, male gender, dyspnea, increased anxiety symptoms, seizures, illicit drug use, and fewer cardiovascular comorbidities should be considered hypothesis generating. Importantly, age was not a significant predictor of cognitive decline, which challenges the assumption that cognitive decline is solely related to the natural aging process. It suggests that there are unique factors associated with TBI that impact cognitive function, and these factors can affect individuals across the lifespan. The BTACT is a brief and sensitive tool for identifying clinically meaningful changes in cognitive function over a relatively brief period (i.e., 1 year) in a sample of individuals in the chronic stages of TBI (i.e., x̄ = 6.7 years post-TBI). Thus, the BTACT may be useful in surveillance efforts aimed at understanding and detecting decline, particularly in situations where in-person cognitive screening is impractical or unfeasible. We also identified potentially modifiable targets for the prevention of post-TBI cognitive decline. These findings can offer insights into treatment goals and preventive strategies for individuals at risk for cognitive decline, as well as help to facilitate early identification efforts.

Altered functional connectivity of cerebellar subregions in male patients with obstructive sleep apnea: A resting-state fMRI study

PURPOSE

Previous studies have demonstrated impaired cerebellar function in patients with obstructive sleep apnea (OSA), which is associated with impaired cognition. However, the effects of OSA on resting-state functional connectivity (FC) in the cerebellum has not been determined. The purpose of this study was to investigate resting-state FC of the cerebellar subregions and its relevance to clinical symptoms in patients with OSA.

METHODS

Sixty-eight patients with OSA and seventy-two healthy controls (HCs) were included in the study. Eight subregions of the cerebellum were selected as regions of interest, and the FC values were calculated for each subregion with other voxels. A correlation analysis was performed to examine the relationship between clinical and cognitive data.

RESULTS

Patients with OSA showed higher FC in specific regions, including the right lobule VI with the right posterior middle temporal gyrus and right angular gyrus, the right Crus I with the bilateral precuneus/left superior parietal lobule, and the right Crus II with the precuneus/right posterior cingulate cortex. Furthermore, the oxygen depletion index was negatively correlated with aberrant FC between the right Crus II and the bilateral precuneus / right posterior cingulate cortex in OSA patients (p = 0.004).

CONCLUSION

The cerebellum is functionally lateralized and closely linked to the posterior default mode network. Higher FC is related to cognition, emotion, language, and sleep in OSA. Abnormal FC may offer new neuroimaging evidence and insights for a deeper comprehension of OSA-related alterations.

Traumatic brain injury and sleep in military and veteran populations: A literature review

BACKGROUND

Traumatic brain injury (TBI) is a hallmark of wartime injury and is related to numerous sleep wake disorders (SWD), which persist long term in veterans. Current knowledge gaps in pathophysiology have hindered advances in diagnosis and treatment.

OBJECTIVE

We reviewed TBI SWD pathophysiology, comorbidities, diagnosis and treatment that have emerged over the past two decades.

METHODS

We conducted a literature review of English language publications evaluating sleep disorders (obstructive sleep apnea, insomnia, hypersomnia, parasomnias, restless legs syndrome and periodic limb movement disorder) and TBI published since 2000. We excluded studies that were not specifically evaluating TBI populations.

RESULTS

Highlighted areas of interest and knowledge gaps were identified in TBI pathophysiology and mechanisms of sleep disruption, a comparison of TBI SWD and post-traumatic stress disorder SWD. The role of TBI and glymphatic biomarkers and management strategies for TBI SWD will also be discussed.

CONCLUSION

Our understanding of the pathophysiologic underpinnings of TBI and sleep health, particularly at the basic science level, is limited. Developing an understanding of biomarkers, neuroimaging, and mixed-methods research in comorbid TBI SWD holds the greatest promise to advance our ability to diagnose and monitor response to therapy in this vulnerable population.

Obstructive sleep apnea is associated with worse cognitive outcomes in acute moderate-to-severe traumatic brain injury: A TBI Model Systems study

OBJECTIVE

To examine the relationship between polysomnography-classified obstructive sleep apnea (OSA) severity and cognitive performance in acute moderate-to-severe traumatic brain injury (TBI).

METHOD

This was a cross-sectional, secondary analysis leveraging data from a clinical trial (NCT03033901) and TBI Model Systems. Sixty participants (mean age = 50 ± 18y, 72% male, 67% white) with moderate-to-severe TBI from five civilian rehabilitation hospitals were assessed at one-month post-injury. Participants underwent Level 1 polysomnography. OSA severity was classified as mild, moderate, and severe using the Apnea-Hypopnea Index (AHI). Associations between OSA metrics of hypoxemia (nadir and total time spent below 90%) and AHI with cognition were examined. Cognition was assessed with the Brief Test of Adult Cognition by Telephone (BTACT), which is comprised of six subtests assessing verbal memory, attention/working memory, processing speed, language, and executive function.

RESULTS

Over three-quarters of this acute TBI sample (76.7%) were diagnosed with OSA (no OSA n = 14; mild OSA n = 19; moderate/severe OSA n = 27). After adjustment for age, gender, and education, those with OSA had worse processing speed, working memory, and executive functioning compared to those without OSA. Compared to those with moderate/severe OSA, those with mild OSA had worse working memory and executive function.

CONCLUSIONS

OSA is highly prevalent during acute stages of TBI recovery, and even in mild cases is related to poorer cognitive performance, particularly in the domains of attention/working memory and executive functioning. Our results support the incorporation of OSA diagnostic tools and interventions into routine clinical care in rehabilitation settings.