It is not that simple. In most brain studies I read there is a stroke or something like that which causes a lesion in the brain, and the changes came about afte

It is not that simple. In most brain studies I read there is a stroke or something like that which causes a lesion in the brain, and the changes came about after this. Since we already have a good idea where the change in the brain comes from, it is reasonable to assume the personality change is caused by it.