In the first part of their study, the researchers examined four postmortem brains from teenage athletes who had sustained head hits and impact injuries 1, 2, 10 and 128 days prior to death. Neuropathological analysis of these brains showed a spectrum of post-traumatic pathology, including one case of early-stage CTE and two cases with abnormal accumulation of tau protein. Brains from four age-matched athletes without recent head injury did not show the pathological changes observed in the head-injury group.
To investigate causal mechanisms underlying these changes, the researchers conducted laboratory experiments using mouse models of two different injury mechanisms—repeat head hits with impact and blast exposure—both linked to CTE. The investigators compared brain responses to the experimental injuries and relationship to CTE pathology over time.
Based on pathological findings in human cases, the researchers hypothesized that early CTE may result from damaged blood vessels in the brain that become leaky, resulting in blood proteins spilling into brain tissue and triggering brain inflammation. The researchers utilized a brain scan called dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to detect leaky blood vessels in the brains of mice subjected to head impact. The investigators also found that head impact caused persistent changes in brain electrical functions, which may explain cognitive difficulties experienced by some people after these injuries.
Content retrieved from: https://www.bumc.bu.edu/camed/2018/01/18/study-hits-not-concussions-cause-cte/.
