Exorcism or mental disorder

Recently I watched a video on CNN about the shortage of preists that
could perform exorcisms. They made an interesting point about
psychology. They suggested that most mentally ill people suffering
from various disorders are actually posessed by the devil. What they
need is an exorcism and not a psychologist. This is an interesting
thought. I am not sure if it applies or not, but we certainly can't
say that psychology is an exact science.