. >> you just kind of feel like kunk, kunk it doesn't really hurt in the moment.ght see a little bit of stars, you get a little dizzy. >> reporter: falls are accidents, even with no loss of consciousness may never show up on a scan. >> some of the changes are microscopic, the impact. and you can't always pick it up. >> reporter: emerging research suggests how well you recover from blows to the head may depend on your genes. specifically genes regulating repair of brain cells. >> they have a long time in between where you can do a lot of positive things if you are armed with this knowledge. >> reporter: former nfl player now brain injury researchers tells me about one in five people have the apoefour gene. >> in a severe brain injury you can provide stem cells that regulate the system and provides a better income. >> reporter: head pain once sent him to the hospital he left without being seen. >> i actually don't have health insurance. like a lot of americans. >> reporter: cognizant trouble can develop. but treatment may save brains. >>> the venue for the oscars ha

. >> you just kind of feel like kunk, kunk it doesn't really hurt in the moment.you might see a little bit of stars, you get a little dizzy. >> reporter: falls are accidents, even with no loss of consciousness may never show up on a scan. >> some of the changes are microscopic, the impact. and you can't always pick it up. >> reporter: emerging research suggests how well you recover from blows to the head may depend on your genes. specifically genes regulating repair of brain cells. >> they have a long time in between where you can do a lot of positive things if you are armed with this knowledge. >> reporter: former nfl player now brain injury researchers tells me about one in five people have the apoefour gene. >> in a severe brain injury you can provide stem cells that regulate the system and provides a better income. >> reporter: head pain once sent him to the hospital he left without being seen. >> i actually don't have health insurance. like a lot of americans. >> reporter: cognizant trouble can develop. but treatment may save brains. >>> the venue for the osc