Football safety has increased over time, in part due to improvements in equipment and body mechanics, but there are still inherent risks involved, including exposure to repetitive head impacts (RHI). Significant head impacts can result in a constellation of symptoms including nausea, vomiting, headache, dizziness, and amnesia, which typically assist in the diagnosis of concussion. However, it has been shown that subconcussive impacts may result in microstructural changes and physiological alterations in the brain. This is particularly concerning because athletes may be undergoing changes in the brain in the absence of outwardly visible symptoms. Poorer neurologic outcomes later in life have been associated with cumulative exposure rather than number of diagnosed concussions. Accelerometers installed in helmets have shown that college football players may receive up to 1,850 head impacts throughout the course of one season. The concussion rate is obviously much lower, indicating there are a high number of head impacts per diagnosed concussion. Axons are especially susceptible to damage from RHI because of their extension throughout the nervous system. The subtle changes thought to result from RHI are not easy to measure, but several modalities have been proposed. These include diffusion tensor imaging (DTI), plasma tau protein, and King-Devick testing. The proposed study will look to quantify cumulative head impact exposure in college football players prior to the start of a season and see if this has any impact on the variables. They will then participate in one season of football wearing helmet accelerometers to measure the number of head impacts sustained. Changes in the variables will be compared to non-contact sport college athletes. Data will be analyzed to determine if number of head impacts correlates with changes in variables and if prior head impact exposure has any effect on these changes. Data obtained from this study will have significant implications in the field of head injury. It may strengthen the use of several markers of brain injury that could be utilized in the future. Additionally, the effects of cumulative head impact exposure and one season of head impacts will be thoroughly examined. This information can be provided to trainers, coaches, and athletes to further improve football safety.

Contact and collision sports (CCS) expose athletes to countless repetitive head impacts (RHI) across a single season, potentially leading to increased risk of long-term difficulties in cognition and the development of neurodegenerative disease. There is mixed literature on whether RHI from CCS result in changes to white matter and long-term neurobehavioral outcomes, therefore this research project seeks to provide supporting evidence by comparing the total volume of fluid-attenuated inversion recovery (FLAIR) white matter lesions in individuals with a history of RHI from CCS to those without a history of RHI from the Boston University Alzheimer’s Disease Research Center (BU ADRC). The RHI participants were matched to a group of non-RHI participants based on age (+/- 5 years). Effects of RHI on white matter hyperintensities (WMHs) are evaluated, while considering hippocampal volume across RHI and non-RHI groups. When controlling for age, sex, education, and total hippocampal volume, those with a history of football were found to have a significantly greater WMH volume (p=.02) compared to those without a history of football play. Compared to the non-RHI group, the RHI group including all athletes (n=42) had a greater WMH volume, although it did not reach a level of significance (p=.91). This investigation provided preliminary evidence for a link between high RHI exposure and WMHs in football players, and a non-significant relationship between RHI and increased WMHs in those with a history of CCS compared to individuals in the non-RHI group. Future research should expand upon this investigation, by examining RHI exposure and WMH consequences in a diverse assortment of sports, follow athletes longitudinally for repeated in vivo MRIs and post-mortem neuropathological confirmation, and include more female athletes.

BACKGROUND: Sports-related head trauma has become a major public health concern with significant consequences including persistent post-concussion syndrome (pPCS) and chronic traumatic encephalopathy (CTE). pPCS is a condition where symptoms of single concussion persist years beyond the initial injury. CTE has been characterized as a condition with insidious onset following a latent period after substantial exposure to repetitive head impacts (RHI). Timing of symptom onset usually distinguishes these conditions, however in certain clinical situations a definitive diagnosis is not always clear. For these situations, a measurable distinguishing variable is necessary. LITERATURE REVIEW: Concussions are the most common form of traumatic brain injury (TBI) and are associated with a variety of neurological symptoms that usually resolve within weeks. Post-concussion syndrome (PCS) refers to cases where symptoms continue months beyond this window, and pPCS is defined as symptoms continuing over years. These conditions are temporally related single concussive events. CTE is the hallmark condition related to RHI and remains difficult to fully characterize as it currently can only be diagnosed post-mortem. Clinical features of CTE are similar to those of pPCS with notable behavioral/mood symptoms in its earliest stages, and progression to severe cognitive decline over time. Current research has shown executive dysfunction to be a common impairment among these conditions. The difference in level of dysfunction between them, if one exists, is yet to be measured. PROPOSED PROJECT: A cross-sectional analysis of executive function in four groups. A control without history of mTBI or football exposure (Non-Football – pPCS), a second control of asymptomatic subjects with football exposure (Football – pPCS), a group of pPCS patients with non-athletic mTBI history (Non-Football + pPCS), and a group of pPCS patients with football exposure (Football + pPCS). Executive functioning will be evaluated using the BRIEF-A assessment. Results will be compared to determine if significant differences in executive functioning exist between the groups. CONCLUSIONS: With previous studies showing a correlation between CTE pathological stage, worsening executive function, and increased RHI exposure, further investigation into using executive function as a distinguishing variable between early stage CTE and pPCS is warranted. SIGNIFICANCE: Results of this study, if significant, could be applied clinically to assess risk of early stage CTE in athletes with prolonged post-concussion symptoms. If results are not significant, they may still be utilized for a better understanding of the effects of isolated mTBIs and RHI on executive functioning, and provide valuable information for ongoing longitudinal studies.

CTE is a progressive neurodegenerative disease defined by p-tau lesions in characteristic locations of the brain, leading to cognitive impairment as well as mood and behavioral dysfunction. Exposure to repetitive head impacts is a major risk factor for developing CTE; however, additional risk factors and secondary modulating factors, which may expand available treatment and prevention options, are still being elucidated. Studies into the glymphatic system, a system of waste clearance in the brain thought to be activated during sleep, have implicated glymphatic dysfunction in the clearance of toxic proteins like amyloid-beta and hyperphosphorylated tau, as well as in cognitive decline in neurodegenerative disorders like Alzheimer’s Disease, bringing into question whether sleep, through impacting glymphatic clearance, may act as a modulating factor in the development of CTE. In the present study, we began to characterize the presence of sleep disorders and their co-morbid conditions in a cohort of former college football players to gain better insight into their prevalence and the health outcomes of those with sleep conditions. Our results found higher rates of sleep apnea in the study sample, as well as an association between diagnosis with sleep apnea and diagnosis with dementia, AD, MCI, CTE, and similar disorders. Sleep apnea was significantly associated with depression, anxiety, high cholesterol, and diabetes. Further research into whether sleep disorders exacerbate CTE pathology or clinical symptoms, and whether treatment of sleep symptoms leads to better outcomes for patients with CTE, is necessary to further elucidate a potential connection.