Autism- Once thought of as extremely early-onset schizophrenia, this condition was believed to be caused by parental detachment. Professional literature recommended treating affected children with electroshock therapy and LSD well into the 1970s. It wasn't until 1989 that the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), the reference book health care professionals use to diagnose mental disorders, listed autism as a developmental disorder separate from schizophrenia.
Moral of the story: Science is continually evolving. As a result sometimes even the experts are wrong. Question everything.