Cumulative Effects of Repetitive Mild Traumatic Brain Injury

Abstract

The majority of traumatic brain injuries (TBI) in the USA are mild in severity. Sports, particularly American football, and military experience are especially associated with repetitive, mild TBI (mTBI). The consequences of repetitive brain injury have garnered increasing scientific and public attention following reports of altered mood and behavior, as well as progressive neurological dysfunction many years after injury. This report provides an up-to-date review of the clinical, pathological, and pathophysiological changes associated with repetitive mTBI, and their potential for cumulative effects in certain individuals.

Evaluating glial and neuronal blood biomarkers GFAP and UCH-L1 as gradients of brain injury in concussive, subconcussive and non-concussive trauma: a prospective cohort study

“…These injuries may be irrelevant, or they may represent important trauma that is just below the level of clinical detection and referred to as subconcussive trauma. Emerging data have demonstrated that significant alterations in brain function can occur in the absence of clinically obvious symptoms following even a single head trauma 15 18 19. Given the lack of concussive symptoms acutely, biomarkers (such as GFAP and UCH-L1) could provide a more objective measure of injury and potentially identify those at risk for neurocognitive problems.…”

“…Given the lack of concussive symptoms acutely, biomarkers (such as GFAP and UCH-L1) could provide a more objective measure of injury and potentially identify those at risk for neurocognitive problems. Studies in athletes have documented that both clinically diagnosed concussion and subconcussive traumas can induce similar changes in brain structure and functions on brain imaging 15 19–21. These changes include alterations in white matter and cerebrovascular integrity, blood flow, neuroinflammation, brain activation during working memory tasks, resting-state functional connectivity and brain chemistry as measured by various forms of MRI 20 22 23.…”

“…To date, there is a paucity of studies addressing the effects of subconcussive head impacts following head trauma. The issue of subconcussive trauma has been a particular concern in military personnel13 and in athletes, as repetitive subconcussive impacts have the potential for long-term deleterious effects 14–16. Therefore, studying these biomarkers in patients with head trauma without symptoms could provide unique insights into how neuronal and glial biomarkers behave in subconcussive trauma 17…”

Mild Traumatic Brain Injury Burden Moderates the Relationship Between Cognitive Functioning and Suicidality in Iraq/Afghanistan-Era Veterans

“…In terms of the pathophysiological outcomes resulting from multiple mTBIs, research using various experimental models has demonstrated diffuse axonal injury and demyelination (Bailes, Dashnaw, Petraglia, & Turner, 2014; Fehily & Fitzgerald, 2017), as well as cumulative damage to hippocampal cells (Slemmer, Matser, De Zeeuw, & Weber, 2002). Given that myelin plays a key role in information processing speed and that hippocampal functioning is essential for memory performance, it is not surprising that observed pathophysiological changes in white matter and the hippocampus have been linked to motor and memory dysfunction following multiple mTBIs in both animal and human studies (Mouzon et al, 2012; Multani et al, 2016; Niogi et al, 2008).…”

Age and Diet Affect Genetically Separable Secondary Injuries that Cause Acute Mortality Following Traumatic Brain Injury in Drosophila

“…Once again, analogous experiments have not yet been performed in mammals. Given the potential importance of the relationship between interinjury interval and outcomes in sports where athletes can sustain multiple primary injuries in a short period of time, these data in flies suggest that effects of genotype and diet should be explored in mammalian studies of interinjury interval (Bailes et al 2014). …”