People who’ve had TBI [traumatic brain injuries] have brains that appear older than their chronological age. In other words, TBI appears to accelerate brain aging.
Older brains have less gray and white matter. In other words, more atrophy.
Importantly, concussion is another name for mild TBI. Think about how many concussions kids and adolescents have growing up playing sports…
From the Annals of Neurology 2015