Obstructive Sleep Apnea among Players in the National Football League: A Scoping Review

Clinical Outcomes and Tau Pathology in Retired Football Players: Associations With Diagnosed and Witnessed Sleep Apnea

Background and Objectives

Obstructive sleep apnea (SA) is common in older men and a contributor to negative cognitive, psychiatric, and brain health outcomes. Little is known about SA in those who played contact sports and are at increased risk of neurodegenerative disease(s) and other neuropathologies associated with repetitive head impacts (RHI). In this study, we investigated the frequency of diagnosed and witnessed SA and its contribution to clinical symptoms and tau pathology using PET imaging among male former college and former professional American football players.

Methods

The sample included 120 former National Football League (NFL) players, 60 former college players, and 60 asymptomatic men without exposure to RHI (i.e., controls). Diagnosed SA was self-reported, and all participants completed the Mayo Sleep Questionnaire (MSQ, informant version), the Epworth Sleepiness Scale (ESS), neuropsychological testing, and tau (flortaucipir) PET imaging. Associations between sleep indices (diagnosed SA, MSQ items, and the ESS) and derived neuropsychological factor scores, self-reported depression (Beck Depression Inventory-II [BDI-II]), informant-reported neurobehavioral dysregulation (Behavior Rating Inventory of Executive Function-Adult Version [BRIEF-A] Behavioral Regulation Index [BRI]), and tau PET uptake, were tested.

Results

Approximately 36.7% of NFL players had diagnosed SA compared with 30% of the former college football players and 16.7% of the controls. Former NFL players and college football players also had higher ESS scores compared with the controls. Years of football play was not associated with any of the sleep metrics. Among the former NFL players, diagnosed SA was associated with worse Executive Function and Psychomotor Speed factor scores, greater BDI-II scores, and higher flortaucipir PET standard uptake value ratios, independent of age, race, body mass index, and APOE ε4 gene carrier status. Higher ESS scores correlated with higher BDI-II and BRIEF-A BRI scores. Continuous positive airway pressure use mitigated all of the abovementioned associations. Among the former college football players, witnessed apnea and higher ESS scores were associated with higher BRIEF-A BRI and BDI-II scores, respectively. No other associations were observed in this subgroup.

Discussion

Former elite American football players are at risk of SA. Our findings suggest that SA might contribute to cognitive, neuropsychiatric, and tau outcomes in this population. Like all neurodegenerative diseases, this study emphasizes the multifactorial contributions to negative brain health outcomes and the importance of sleep for optimal brain health.

Association of Vascular Risk Factors and CSF and Imaging Biomarkers With White Matter Hyperintensities in Former American Football Players

BACKGROUND AND OBJECTIVES

Recent data link exposure to repetitive head impacts (RHIs) from American football with increased white matter hyperintensity (WMH) burden. WMH might have unique characteristics in the context of RHI beyond vascular risk and normal aging processes. We evaluated biological correlates of WMH in former American football players, including markers of amyloid, tau, inflammation, axonal injury, neurodegeneration, and vascular health.

METHODS

Participants underwent clinical interviews, MRI, and lumbar puncture as part of the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Structural equation modeling tested direct and indirect effects between log-transformed total fluid-attenuated inversion recovery (FLAIR) lesion volumes (TLV) and the revised Framingham stroke risk profile (rFSRP), MRI-derived global metrics of cortical thickness and fractional anisotropy (FA), and CSF levels of amyloid β1-42, p-tau181, soluble triggering receptor expressed on myeloid cells 2 (sTREM2), and neurofilament light. Covariates included age, race, education, body mass index, APOE ε4 carrier status, and evaluation site. Models were performed separately for former football players and a control group of asymptomatic men unexposed to RHI.

RESULTS

In 180 former football players (mean age = 57.2, 36% Black), higher log(TLV) had direct associations with the following: higher rFSRP score (B = 0.26, 95% CI 0.07-0.40), higher p-tau181 (B = 0.17, 95% CI 0.01-0.43), lower FA (B = -0.28, 95% CI -0.42 to -0.13), and reduced cortical thickness (B = -0.25, 95% CI -0.45 to -0.08). In 60 asymptomatic unexposed men (mean age = 59.3, 40% Black), there were no direct effects on log(TLV) (rFSRP: B = -0.03, 95% CI -0.48 to 0.57; p-tau181: B = -0.30, 95% CI -1.14 to 0.37; FA: B = -0.07, 95% CI -0.48 to 0.42; or cortical thickness: B = -0.28, 95% CI -0.64 to 0.10). The former football players showed stronger associations between log(TLV) and rFSRP (1,069% difference in estimates), p-tau181 (158%), and FA (287%) than the unexposed men.

DISCUSSION

Risk factors and biological correlates of WMH differed between former American football players and asymptomatic unexposed men. In addition to vascular health, p-tau181 and diffusion tensor imaging indices of white matter integrity showed stronger associations with WMH in the former football players. FLAIR WMH may have specific risk factors and pathologic underpinnings in RHI-exposed individuals.

Sleep and cardiovascular disease

This review centres around the recent evidence in examining the intersection of sleep and cardiovascular disease (CVD). Sleep in this review will be further subdivided to consider both sleep quantity and quality along and will also consider some of the more common sleep disorders, such as insomnia and obstructive sleep apnoea, in the context of CVD. Sleep disorders have been further explored in several specific populations which are both at risk of sleep disorders and CVD. Secondly, the review will present some of the risk factors for CVD that are affected by sleep and sleep disorders which include hypertension, diabetes, and obesity. It will also examine the potential underlying mechanisms including inflammation, appetite control, endocrine, and genetic processes that are affected by sleep and sleep disorders leading to increased risk of CVD development. In addition, we will consider the observed bi-directional relationships between sleep and cardiovascular risk factors. For example, obesity, a risk factor for CVD can be affected by sleep, but in turn can increase the risk of certain sleep disorder development which disrupts sleep, leading to further risk of obesity development and increased CVD risk. Finally, the review will explore emerging evidence around lifestyle interventions that have included a sleep component and how it impacts the management of CVD risk factor. The need for increased awareness of the health effects of poor sleep and sleep disorders will be discussed alongside the need for policy intervention to improve sleep to facilitate better health and well-being.

Chronic Traumatic Encephalopathy: A Comparison with Alzheimer's Disease and Frontotemporal Dementia

The clinical diagnosis of chronic traumatic encephalopathy (CTE) is challenging due to heterogeneous clinical presentations and overlap with other neurodegenerative dementias. Depending on the clinical presentation, the differential diagnosis of CTE includes Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), Parkinson's disease, amyotrophic lateral sclerosis, primary mood disorders, posttraumatic stress disorder, and psychotic disorders. The aim of this article is to compare the clinical aspects, genetics, fluid biomarkers, imaging, treatment, and pathology of CTE to those of AD and bvFTD. A detailed clinical evaluation, neurocognitive assessment, and structural brain imaging can inform the differential diagnosis, while molecular biomarkers can help exclude underlying AD pathology. Prospective studies that include clinicopathological correlations are needed to establish tools that can more accurately determine the cause of neuropsychiatric decline in patients at risk for CTE.

Premortem Chronic Traumatic Encephalopathy Diagnoses in Professional Football

OBJECTIVE

American-style football (ASF) has gained attention because of possible links between repetitive head injury and neurodegenerative diseases. Although postmortem pathologic changes consistent with chronic traumatic encephalopathy (CTE) have been reported in ASF players, there are currently no established premortem diagnostic criteria for CTE. Nevertheless, presented with symptoms of cognitive impairment, clinicians treating former players may be inclined to suggest CTE without a thorough exploration of comorbid factors that demonstrate similar clinical phenotypes to putative CTE.

METHODS

A survey of 3,913 former ASF players aged 24 to 89 was conducted for those who responded by March 2019.

RESULTS

Despite being a postmortem diagnosis, 108 players (2.8%) self-reported clinician-diagnosed CTE. The percentage of players under age 60 years reporting a CTE diagnosis was 2.3% versus 3.7% in participants age 60 or older. Comorbidities in participants self-reporting CTE were significantly more common, including sleep apnea, hypercholesterolemia, obesity, indicators of past or current depression, hypertension, prescription pain medication use, heart conditions, and low testosterone when compared to non-CTE respondents. Patterns of reporting for obesity, hypertension, heart conditions, or hypercholesterolemia differed between older and younger participants. Cognitive impairment symptoms were significantly higher in participants self-reporting CTE.

INTERPRETATION

Some former professional football players have been clinically diagnosed with CTE, a postmortem condition. Comorbidities that can affect cognition were associated with CTE diagnoses in both older and younger players. Although underlying neuropathology cannot be ruled out, treatable conditions should be explored in former athletes demonstrating CTE-linked clinical phenotypes or symptoms as a means of improving cognitive health in these patients. ANN NEUROL 2020 ANN NEUROL 2020;88:106-112.

Obstructive Sleep Apnea Risk and Stroke among Blacks with Metabolic Syndrome: Results from Metabolic Syndrome Outcome (MetSO) Registry

INTRODUCTION

The American Stroke Association estimates that stroke is the fifth leading cause of death in the United States. According to the Center for Disease Control and Prevention someone in the United States has a stoke every 40 seconds, affecting more than 795,000 people of which 140,000 result in death [1]. Emerging evidence suggests that obstructive sleep apnea (OSA) is a strong risk factor for stroke. This study using The Metabolic Syndrome Outcome (MetSO) registry explored whether blacks at risk for obstructive sleep apnea (OSA) are at greater risk for a stroke.

METHOD

The present study utilized data from the MetSO study, an NIH-funded cohort study of blacks with metabolic syndrome (MetS). Patients were diagnosed with MetS using standard criteria articulated in the joint interim statement for harmonizing the MetS. The study assessed OSA risk using the Apnea Risk Evaluation System (ARES); defining high risk as a total ARES score ≥6. Data was coded and analyzed by an experienced statistician using SPSS 20.0.

RESULTS

A total of 1035 participants were screened for MetS in the MetSO registry. During the data collection period 875 participants were enrolled during the time of analysis. The average age of the sample was 62±14 years (range: 20-97); 71% were female, and all were of black race/ethnicity. Seventy-one percent reported finishing high school, and 43% reported annual income <10K. Descriptive analyses showed 93% of the participants were diagnosed with hypertension; 61%, diabetes; 72%, dyslipidemia; 90% were overweight/obese; 33% had a history of heart disease and 10% had a stroke history. Using the ARES screener, we estimated that 48% were at high risk for OSA. Logistic regression analysis, adjusting for age and gender, showed that patients at high risk for OSA had a nearly three-fold increase in the odds of having a stroke (OR = 2.79, 95% CI: 1.64-4.73).

CONCLUSION

In the MetSO registry, a cohort of blacks with MetS, the prevalence of stroke is greater than in the general US population. Blacks at risk for OSA are particularly vulnerable to experiencing a stroke.

Interactive Effects of Racial Identity and Repetitive Head Impacts on Cognitive Function, Structural MRI-Derived Volumetric Measures, and Cerebrospinal Fluid Tau and Aβ

BACKGROUND

Factors of increased prevalence among individuals with Black racial identity (e.g., cardiovascular disease, CVD) may influence the association between exposure to repetitive head impacts (RHI) from American football and later-life neurological outcomes. Here, we tested the interaction between racial identity and RHI on neurobehavioral outcomes, brain volumetric measures, and cerebrospinal fluid (CSF) total tau (t-tau), phosphorylated tau (p-tau181), and Aβ1 - 42 in symptomatic former National Football League (NFL) players.

METHODS

68 symptomatic male former NFL players (ages 40-69; n = 27 Black, n = 41 White) underwent neuropsychological testing, structural MRI, and lumbar puncture. FreeSurfer derived estimated intracranial volume (eICV), gray matter volume (GMV), white matter volume (WMV), subcortical GMV, hippocampal volume, and white matter (WM) hypointensities. Multivariate generalized linear models examined the main effects of racial identity and its interaction with a cumulative head impact index (CHII) on all outcomes. Age, years of education, Wide Range Achievement Test, Fourth Edition (WRAT-4) scores, CVD risk factors, and APOEε4 were included as covariates; eICV was included for MRI models. P-values were false discovery rate adjusted.

RESULTS

Compared to White former NFL players, Black participants were 4 years younger (p = 0.04), had lower WRAT-4 scores (mean difference = 8.03, p = 0.002), and a higher BMI (mean difference = 3.09, p = 0.01) and systolic blood pressure (mean difference = 8.15, p = 0.03). With regards to group differences on the basis of racial identity, compared to White former NFL players, Black participants had lower GMV (mean adjusted difference = 45649.00, p = 0.001), lower right hippocampal volume (mean adjusted difference = 271.96, p = 0.02), and higher p-tau181/t-tau ratio (mean adjusted difference = -0.25, p = 0.01). There was not a statistically significant association between the CHII with GMV, right hippocampal volume, or p-tau181/t-tau ratio. However, there was a statistically significant Race x CHII interaction for GMV (b = 2206.29, p = 0.001), right hippocampal volume (b = 12.07, p = 0.04), and p-tau181/t-tau ratio concentrations (b = -0.01, p = 0.004).

CONCLUSION

Continued research on racial neurological disparities could provide insight into risk factors for long-term neurological disorders associated with American football play.

Mental health in elite athletes: International Olympic Committee consensus statement (2019)

Mental health symptoms and disorders are common among elite athletes, may have sport related manifestations within this population and impair performance. Mental health cannot be separated from physical health, as evidenced by mental health symptoms and disorders increasing the risk of physical injury and delaying subsequent recovery. There are no evidence or consensus based guidelines for diagnosis and management of mental health symptoms and disorders in elite athletes. Diagnosis must differentiate character traits particular to elite athletes from psychosocial maladaptations.

Management strategies should address all contributors to mental health symptoms and consider biopsychosocial factors relevant to athletes to maximise benefit and minimise harm. Management must involve both treatment of affected individual athletes and optimising environments in which all elite athletes train and compete. To advance a more standardised, evidence based approach to mental health symptoms and disorders in elite athletes, an International Olympic Committee Consensus Work Group critically evaluated the current state of science and provided recommendations.