If anti-psychotics do cause brain shrinking, that is also called atrophy or encephalopathy. There is no way the brain can heal while brain cells are dying.

The research I have read says anti-psychotics should not be used for more than 6 months except in extreme circumstances such as keeping a psychotic person from becoming unable to care for themselves or a danger. My doc wanted me on Xyprexa for only 30 days. I was having a severe PTSD response and it helped me get past it.