Tuesday, May 10, 2011

Autism is NOT an epidemic

ARRRGGHHHH... There are relatively few things outside of religion which get on my nerves more than the anti-vaccine movement.  The fallacies abound in this crowd where the entirety of the beliefs are based on logical failures and incomplete information.

One major aspect that comes up in the argument is that the rate of autism is many times higher now than before.  Even around the time I was born, the rate of autism diagnoses was something like 1 in 8,000, and now it's 1 in 110 or so.  What happened?  It must either be a new epidemic of some sort or something has poisoned the well.  It's 'dem dere evil pharmaceutical companies!!!

The key word nobody notices here is that it's the rate of diagnoses which has increased.  Not the rate of incidence.

Ars reported on a recent paper in the Archives of General Psychiatry which tried to collect data on the epidemiology of autism spectrum disorders.  Till date, there has been no such collection of data.  The basic approach of the study was to take the current established rate of diagnoses for children and compare it to a sampling of the current adult population where they attempted a diagnosis according to the same criteria used in modern conditions.  Result?  Roughly the same rate of diagnosis.  Yes, I know it's only a preliminary study, and it has a fairly small sample size which makes the confidence interval really wide (funny, though, how the sample size of 12 in Wakefield's paper is considered conclusive proof for anti-vaxxers, but real science considers a sample size of 850 too small to make final conclusions).

Well, the main point is that it strongly indicates that there is no epidemic.  We're just being more proactive in diagnosing it.  Also, there's the fact that back when the rate of diagnosis was around 1 in 8,000, there were a variety of conditions all considered disparate...  now, some 20 or 30 previously different conditions are all categorized under the umbrella of "autism spectrum disorders."  It gets from the very extreme "Rain Man"-esque kinds of autism to the extremely mild higher functioning forms like Asperger's Syndrome, which is pretty much the level of the weird kid in class who keeps to himself (it's generally nowhere near the severity portrayed in My Name is Khan).

We're just better at finding it...  as well as a having a certain increased chance of finding it when it isn't actually there.  But then, if you, the reader are not an anti-vaxxer, I don't expect you to have any real doubts on that...  and if you are, well, then...  get your damn facts straight, already.