Question: how does brain damage happen and how long does it take to happen

Daniel Mietchen answered on 20 Jun 2010:

A stroke (i.e. the blocking of a blood vessel in the brain) can cause brain damage within seconds. Lack of oxygen does the same thing within minutes. Both basically switch of the energy supply for the cells, and both can be fatal. In contrast, diseases like Alzheimer’s (which is much less understood) develop over decades.