How do researchers know that the amount of kids with autism is increasing and not just the rate of kids being diagnosed is increasing?

I wish I could give you an answer, but in the case of my son, it was not diagnosed until he was 9. Why? Because there was too much bickering between the school district, his specialist, and the insurance over who would perform the testing, who would pay, IEP stuff. It was really an exhausting experience. I think maybe the rise maybe due to more school districts knowing the signs, especially of high functioning autism spectrum, which my son is. And maybe the insurance companies being forced to pay for some treatments now, as well as testing, make it more available.

After reading an article (source to be added upon request) that linked Magnesium Deficiency and Autism, "ADHD", and Depression, I started to take it as a supplement to see if it would improve my cognition and boost my moods. It does work for that- my mind was de-fogged and I felt happier. I knew it could not be a placebo effect because the mental fog that sweeps over me is profound and almost always unshakable. When an episode started, I popped a pill and noticed a marked difference in about an hour. Clarity returned. I'm saying all this because I do believe that many, many people are magnesium deficient. It is no longer in our soil, and therefore no longer in our food. There are still so many refined products that people eat, products that in one way or another get the Magnesium inadvertently removed. Far harder to come by are truly whole-grain products that provided enough of this mineral. In summary, even if it were not Magnesium deficiency per se that is causing the rapid increase in cases of autism diagnoses, it really must be some environmental, perhaps nutritional factor that is causing a lot of the trouble.

Well, the fact is that probably rates of autism aren’t increasing. A number of people who would have been diagnosed as mentally retarded two generations ago are now diagnosed as autistic, and this was probably done eyes-wide-open by some doctors. Two generations ago there was no place for autistic people who were more than mildly affected and couldn’t function in a regular school classroom; the only place for them was a mental institution. There were, however, schools for the mentally retarded in most states. Autistic people who were capable of any learning could usually function fairly well in schools for the mentally retarded, especially autistic people who could speak.Since most lay people had not heard of autism (I’m speaking of roughly 1940–1960), it was pretty easy to label an autistic child as mentally retarded, and not have it questioned. If any of the people at schools who received these children recognized what was happening, they were probably happy to deal with each child on a case-by-case basis. They knew what was in store for a child labeled autistic, and if the school for the mentally retarded could serve the child, he might as well carry the label “retarded.”In the 1960s and early 1970s, a new label emerged, which has since been abandoned, called “childhood schizophrenia.” It was simply a way of describing a type of autism, but no one realized it then. Autistic people had mostly been observed in institutional settings, and many of the things they’d been observed doing were the result of years of institutionalization, not autism itself. So when people saw autism “in the wild,” so to speak, they weren’t quite sure what to make of it, and came up with a new diagnostic category. It was abandoned in the late 1970s, and in the 1980s and 90s, adults who had been diagnosed with “childhood schizophrenia” and were still classified as schizophrenic had their diagnoses revised to autism, so many new cases of autism in the 80s and 90s were adults whose diagnoses were revised, not children who were genuine new cases; however, they still contributed to the swelling of numbers.The numbers continue to grow as a result of the awareness campaigns in the 90s and 2000s, because now many, many more children by an order of magnitude are presented for diagnosis in the first place.In 1940–1960, a school district might see a single child presented for a diagnosis in five years. From 1960–1970, it might be five a year, and the child might end up autistic, or with “childhood schizophrenia.” Now it’s more like five per school, per year, although probably one in five doesn’t receive the diagnosis, and still, only about five per year per district are “low functioning,” and are the same children who would have been presented in 1960–70.So while many, many more people are high-functioning autistics, these are people who went undiagnosed— the weird kid in school who did OK academically— sometimes did very well— but never had any friends, and probably got picked on a lot.The number of kids who have little language and may seem bright in some ways, but function as retarded because of their communication deficits, and engage in some stimming activities, and are just generally obviously autistic, hasn’t changed much. There’re more of them, because the population as a whole has grown, but as a percentage of the population, they have not really increased. Their numbers may go through fluxes— they probably rose along with the rubella epidemic in the late 1960s when there was also a rise in the number of people born deaf, and they may be rising slightly now along with CP and ADHD, which appear to be linked to prematurity. There are lots of changes in society that may account for small fluctuations. Statistically, autism is slightly associated with elderly fathers (not middle-aged fathers, but men over fifty-six who father children); so drugs like Viagra may contribute to a minor spike in autism.There are a great number of variables. But as a percentage of the population, the number of kids with autism in the severe-profound range probably has not changed significantly. Most of the growth in the population has been in children with mild-moderate autism, and adults newly diagnosed, even if they had a revision of some other diagnosis, and were already in the system.