Aliceinboots
"A social communication disorder is just another term for ASD, right?"
A very debatable statement. There are many forms of communication disorders, most of which can contribute as part of the multiple issues experienced by those who are included on the Autistic Spectrum.
International researchers are still trying to unravel the issues which contribute to ASD. Some of the issues are already recognised as individual and separate conditions, which on their own would not be considered as ASD.
ASD is currently diagnosed by subjective observation of behavior, which has to meet at least 6 from 12 behavior traits and from in specific combinations of traits. As yet there is no what is called "Scientific Diagnosis" of ASD. progress is being made in providing many "Scientific Diagnosis" processes for the individual conditions which can combine ( or be co morbid, co exist) to cause the ASD behavior traits, but there is still a long way to go.
It is recommended to identify ASD traits etc as early as possible, from 2 - 3 years of age. The individual or contributory issues, can be considered part of natural development, as we all develop different cognitive skills and abilities at different ages and at different rated until the age of maturation 6 - 8 years of age. And until this stage of natural development children can still grow out of these types of issues. However if there is a family history, the genetic link, of these types of issues, siblings, parents, grand parents, aunts, uncles, cousins etc, then there is more support that these issues will not be grown out of between the ages of 3 - 8 as part of natural development, and that there may be a life long disability which requires a clinical diagnosis, and support.
So ASD is not the only route, but is the route that most are aware of.