Concussions were essentially considered brain bruises back in the day, but we are finding out that they are a lot more than that now. They can be the impetus for early onset dementia, personality changes, mood changes, etc. Concussions can have different effects on different people. Some can become concussed and a few days later be perfectly fine in the short term. Others may have a mild concussion and have post-concussive effects for months to a yr afterward. Some symptoms ranging from headaches to memory loss, vertigo, persistent vomiting and personality changes. We have barely unlocked the majority of the brain's function, so I would be lying to you if I said that we fully understand what happens when the brain gets injured. But for the most part, you could be asymptomatic after them or you could be devastated. Only time will tell