MARK COLVIN: Many aspects of what's now called autism spectrum disorder remain mysterious, but a new study from the University of Queensland says the number of people with the disorder is neither rising nor falling.

The university team crunched the numbers on a wide range of research data from 1990 to 2010. They say that around the world one person in 132 has some level of autism spectrum disorder. They say their analysis of the figures shows that that hasn't changed since 1990.

But not everyone agrees with the findings. Some autism support groups say they're struggling to keep up with demand.

Simon Santow reports.

SIMON SANTOW: Epidemiologists led by researcher Amanda Baxter used data from the landmark Global Burden of Disease initiative to come up with their findings on autism.

AMANDA BAXTER: There is no evidence of prevalence increasing over time.

SIMON SANTOW: She says while there's some evidence growing obesity, the use of pesticides and the advanced age for pregnancy can increase the risk of autism, her research blows a large hole in other arguments commonly put forward. 

AMANDA BAXTER: It is an organic disorder and so it really reinforces the research that's been done over the past 14, 15 years that shows that there is no link in those populations between children being vaccinated and rates of autism. So where vaccinations do occur we're not seeing a higher rate of autistic spectrum disorder.

So it really reinforces a huge body of research out there that disputes those earlier, very sensationalised claims.

SIMON SANTOW: Dr Baxter's based at the Queensland Centre for Mental Health Research at UQ's School of Population Health.

AMANDA BAXTER: This is certainly the largest study that has ever been conducted. We captured, I think, 37 different studies from around the world which did look at several million people in all types of circumstances. But there was definitely a lack of studies from the developing countries.

Autism spectrum disorders have not been prioritised very highly in research or in mental health.

SIMON SANTOW: For Steve Drakoulis, the results don't tally with his experiences.

STEVE DRAKOULIS: I'm a father of a child on the autism spectrum.

SIMON SANTOW: Four years ago, he started out with one support group to help other parents cope.

STEVE DRAKOULIS: And it just kept growing and eventually I created a not-for-profit and it just kept going and going. And at the start of 2013 we had 270 members. We're now over 550 families and that's just in the Sydney metropolitan area. It just keeps growing.

SIMON SANTOW: What goes through your mind when you hear me say and others say, well, the research says that in fact there's no more prevalence of autism than there was, say, 20 years ago?

STEVE DRAKOULIS: I'm absolutely stunned. That's just totally against every experience I've had and all the rest of the parents that I've ever dealt with. We see it all around us, every day.

SIMON SANTOW: As the operations manager for the Autism Community Network in Sydney, he's angry when he sees research that he says will encourage governments to underestimate the problem.

STEVE DRAKOULIS: People are ringing me in tears, almost on a daily basis, saying, "My child's been diagnosed. I don't know what to do." The fact that we were never meant to become what we have become, both through the need out there - we just keep growing - that in itself shows me how much need there is out there.

SIMON SANTOW: Is it possible, do you think, Steve, that there's just more knowledge of it than there ever was before, but it's still the same amount in the community?

STEVE DRAKOULIS: Well, there's greater awareness these days, absolutely, and that's a good thing. But the awareness doesn't mean you're going to get the diagnosis.

The fact that the behaviours are there: the children are not meeting their milestones, that they're being different, and when parents are going out to seek the solutions, well, the autism tag isn't just given for the sake of it. It's because there's reason for it.

SIMON SANTOW: But researcher Dr Amanda Baxter says she has an explanation for the apparent discrepancy between her findings and common perceptions.

AMANDA BAXTER: In fact, when I started looking at the research I realised that very little of the research actually reported that prevalence had increased. A lot of those reports that we hear about are simply anecdotal or in the media. But the research has certainly supported our findings.

MARK COLVIN: Dr Amanda Baxter from University of Queensland's Centre for Mental Health Research ending Simon Santow's report.

from http://www.abc.net.au/pm/content/2014/s4067291.htm 

There are also reports here, here and here. The PubMed link is here.