Is it true that when people have a fiver, and you take an aspirin could that bring to a brain damage?

Not likely : There is no expectation that Aspirin causes brain damage when used in regular doses to treat fever. In young children Aspirin was associated with reys syndrome, a very severe and potentially life threatening condition. . Acetaminophen is the recommended substitute in yoiung children.

Aspirin: Aspirin is often given for a fever and very rare to have brain damage as a result, especially in one who is otherwise healthy.