Concussion has one hundred years without resolve it. The imbalance between ions in concussion produces a lot of sleep to try to repair brain damage. The liquid in brain is reducing because the immunologic cells need to repair more quickly and they need to be more in contact. If they have more space to move is possible the reparation will prolong in time.
Also if a reduction of liquid occurs less toxic can go inside the brain and the reparation will be quick. In children and elderly the brain blood barrier can be not so efficient so more toxics can go inside the brain, such as every day and the time to repair brain will be longer.