Does multiple head traumas cause brain ischemia?

Post-traumatic: Repetitive head trauma results in tissue changes quite similar to alzheimers but the lesions are closer to the brain surface. This was first noted in "punch drunk syndrome" in boxing. There is likely some affect on blood flow (ischemia), as one could conceive of a local type of bruising, but this not fully clarified. Regardless the nfl and nhl are both paying a lot of attention these days.