MMR-- => measles++ and autism??

So one thing occurred to me reading the chapter in Bad Science on the MMR fiasco.

We can thank Wakefield for causing the UK to do one experiment no
ethics committee would have let us do - which is to massively decrease
the level of vaccination against measles, mumps and rubella, and see
how long it takes for the diseases to pick up abgain in the
population. This must be a source of invaluble data for
epidemiologists.

But (I didn't see this in the book, maybe its there and I was
laughing at the funny bits too much to spot it) we also ought to be
able to detect any other changes - crucially for example, if the
MMR-gang were a tiny tiny tiny bit right, then the drop in MMR levels
(proved by the current measles outbreak) would lead to a drop (or
slowdown in increase) in Autistic spectrum kids....has anyone done
this study? [I know I know it shouldn't be necessary) - hey though, what if autism went up even more and it appeard MMR protected people slightly from autism or else the people that worry about things like MMR are more likely to have autistic kids and some element of the way the kids are treated or the spectrum is diagnosed or whatever other effect) could be fascinating to find nothing or something!