Abstract
Chronic traumatic encephalopathy-neuropathologic change (CTE-NC) has been studied in contact sport athletes with repetitive head impacts (RHI), but its association with isolated traumatic brain injury (iTBI) and non-sport RHI in the community remains unclear. Forty-seven consecutive donor brains from the Late Effects of TBI Project underwent comprehensive neuropathologic evaluation. Seven (14.9%; median age, seventh decade) had CTE-NC, defined as perivascular neuronal tau at the depth of sulcus. Four had 4 "low" CTE-NC burden, 1 "high," and 2 "indeterminate." Ex vivo neuroimaging in 5 facilitated histological sampling of subtle changes otherwise likely to be overlooked. Five of the 7 CTE-NC donors reportedly had substantial RHI exposure: football (n = 3), boxing (n = 1), military and interpersonal violence (n = 1), and child abuse (n = 1). One CTE-NC case had no known RHI exposure but had 2 severe iTBIs sustained 30 and 3 years prior to death. Donors without CTE-NC had variable patterns of head trauma: RHI exposure (college football, n = 4), some RHI (n = 21, 17 of whom also had ≥1 iTBI), and ≥1 iTBI but no RHI (n = 15). These findings converge with prior reports that CTE is largely associated with extensive RHI and is infrequent in a cohort with varying TBI exposures.