Concussion, TBI, PTSD, PCS can lead to inflammation and cerebral ischemia (deficient supply of blood to the brain that is due to obstruction of the inflow of arterial blood). A host of negative chemical processes begin, along with mitochondrial/cell damage, oxidative damage and apoptosis (cell death). There can be a breakdown of the blood-brain-barrier and brain swelling. Numerous animal studies on concussion and blast injuries confirm that blows to the head are just not good for your brain. And not treating them can lead to severe complications over time, up to and including early onset dementia and Chronic Traumatic Encephalopathy (CTE).