Are you suggesting the autism epidemic is a product of better diagnosis? If so, where are all the autistic 50 year olds?
The autism "epidemic" is largely being caused by an expansion of the definition of autism. Hence, lots of young people with Asperger's, and other mild autisms, but not many 50-year-olds. They're not being diagnosed. (Whether Asperger's is an actual syndrome or just a product of upbringing and personality type: that's a different argument. I tend toward the latter -- I am skeptical about its existence at all.)
Asperger's is a syndrome - that is, a condition defined and diagnosed only by reference to its symptoms. Doubting that there is a single underlying cause is valid, and not even terribly controversial - one of the two psychs who diagnosed me (earlier this year; I'm in my mid-30s) told me that she could buy that as a label it could apply to half a dozen or more underlying causes. But doubting that it's a syndrome is... well, a bit silly. :)
Not quite, a syndrome is a set of correlated symptoms.
Basically, consider the sumptoms of deafness, impotence and tingling in the hands and feet (D, I and T). Suppose that deafness, impotence and tingling are all independent of each other (P(D | I) = P(D)). In this case, there is no syndrome. If, however, they are strongly correlated(P(D | I) >> P(D)), we have a syndrome.
Basically, "deaf and impotent provides no information about tingling" == no syndrome.
"Deaf and impotent implies a high probability of tingling" == syndrome.
As described in the article, autistic people are almost completely dysfunctional. Have you ever met one? It's a bit ridiculous to suggest full blown autism was occurring at current rates, which are having serious public school budget impacts, in the past and nobody noticed. And even more ridiculous to suggest that nobody has bothered to look for all these previously undiagnosed adult autism sufferers, who would have to still be living with their parents or institutionalized.
I don't think it is inconceivable that the adult autism sufferers remain undetected. Presumably, their lives are already arranged. Either they survived somehow, or they didn't. If they survived, there probably is some kind of routine that keeps them alive (maybe an institution, or they live as beggars on the street, or whatever). In that case, why should somebody check up on them again? Sure, it would be nice if somebody would, but why should it happen? When was the last time you learned about some new medical breakthrough and thought "hey, let's go out on the street and check all homeless people to see if they have this condition"? (Not saying older autistic people are homeless, I have no idea how they survive once their parents are dead). Also, there is no cure for autism (or is there?), so simply correcting the diagnosis might not help the older autistic people much (at least not "help" in terms of making it easier for the people they live with - might be easier for themselves, though). Maybe now they are simply sedated with powerful drugs most of the time and don't do much.
Anyway, the main point remains: be careful with "common sense" conclusions.
If they're suggesting that the rise of full-blown autism has somehow risen to epic proportions, they're statistically incorrect. I think they're including milder forms and pretending they're all the same.
The autism "epidemic" is largely being caused by an expansion of the definition of autism. Hence, lots of young people with Asperger's, and other mild autisms, but not many 50-year-olds. They're not being diagnosed. (Whether Asperger's is an actual syndrome or just a product of upbringing and personality type: that's a different argument. I tend toward the latter -- I am skeptical about its existence at all.)