PDD is a label concocted by psychiatrists to cover up the fact that they don't know what your child does have. If any parents have been distressed by this blunt, unexpected harangue on my part, I would be surprised. These parents realize that their handicapped child will in all likelihood be the central focus of their lives for the rest of their lives. They want to know the truth, insofar as the truth is known. They don't want to be misled or misinformed by sugar-coated verbiage masquerading as informed fact.
Mental retardation is a euphemism for low intelligence.
Until we know what causes these things we are stuck with using a somewhat descriptive term to characterize them. The passage of time has led to widespread usage of the terms, schizophrenia, mental retardation and autism. There is little or no likelihood that PDD will be afforded similar acceptance. Autism, they point out, rather than being a pervasive disorder, is in fact a specific one, characterized by deficits in social and cognitive functioning. There are many more children with autistic-like disorders than there are children with autism itself.