This was based on a misunderstanding of autism, and a misunderstanding of which IQ tests work for us.
An average person has an IQ of about 85 to 115. Very few have an IQ below 70 or above 130. If we make a chart of any big group of random people, it may look like this. Along the bottom, their IQ scores. Along the side, how many have that IQ score.
So, normally only about 2 out of every 100 people will have an IQ low enough to be classed as an intellectual disability. (2% means 2 people out of every 100 people, for those who don't speak a lot of maths)
What was our belief about IQ and autism? Here's some typical older research:
1988. Smalley, Asarnow and Spence decided that only a quarter of autistic people had an IQ over 70. The rest, three quarters of autistic people, were believed to have a learning disability/intellectual disability. I'll call this a LD. Not 2 out of every 100. 75 out of every 100. That's a huge huge number who were believed to have a LD, eh.
By 2010, Fernell and team had written research suggesting about 40 out of every 100 autistic young people had a LD. So, the number was dropping.
For 2012, the USA did major research on autistic children and young people. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237390/
It has some interesting stuff in it.
Among all 3,353 autistic children they looked at, on average about 31 out of every 100 had a LD. So that's lower, again.
But varied, a lot. In some States, like Utah, it was only about 20 out of every 100. In others, nearly half the autistic children were said to have a LD.
And it varied by gender, too. 37 out of 100 autistic girls had a LD. Only 30 out of 100 boys.
Fast forward to 2019, and we have a very useful brand new study from Scotland, who looked at nearly all their children in the 2011 Census. This is the link to their work:https://bmjopen.bmj.com/content/9/8/e029040.full
So...when they crunched the numbers for the whole of Scotland, for autistic children, only 15 out of every 100 autistic children also had a LD.
What's going on here, then? Why all these different numbers?
Well, it depends what we're measuring, and how.
First, we need to find all the autistic people. That's not been easy. We had those myths that autism looked like an antisocial young white lad with a low IQ or a total focus on trains (or both...), and of course no speech and deeply unusual behaviour. So we missed the females, People of Colour, extraverts, older people...in fact nearly everyone.
Some countries, and some States, were better at finding the missing people.
Some countries, and some States, were still assuming autism looks like a low IQ and definitely male.
The only way some females got diagnosed is if they also had a LD, and also had some pretty unusual behaviour. The rest weren't discovered, weren't measured.
Then, there's how we measure IQ for autistic people. We'd often been using the wrong tests. Using a Raven's test, the IQ results for autistic people are way higher than we'd realised, for many. Here's a chart where people realised the error. Bit technical, so feel free to skip this explanation: Four sets of bars. Each shows a different IQ test. First two bars in each group of four is the results of female and male autistic people. Second two bars in each group of four is the results of female and male non-autistic people ('controls').
The first three IQ tests showed a whacking great difference between autistic people and the non-autistic ones. But look at that Raven's test. Hardly any difference at all.
It's all quite a challenge, eh?
So....as far as we can tell from the Scottish data, about 15 out of every 100 autistic people also have a LD. And the rest do not. But if you're older, it's become clear from wider research that there's more chance of you being missed from diagnosis, because of the myths. Maybe, if we used the right IQ test, it would be even less than that 15%. I suspect it'll be no different to the rest of the population, to be honest. About 2%. But I can't prove it....yet...
A lot of what we thought we knew about autism has been wrong. A lot of the alleged costs of autistic people was based on the old data about low IQs. A lot of the assumptions about our abilities and employability was based on those old myths, too.
We need to get a grip of what autism is, and is not. It's not a learning disability. And we need to move firmly into 2019. A 2019 where autistic people of all kinds are valued, whatever their IQ. Not seen as burdens and costs, but as marvellous people with so much to offer. My other blogs talk about the honesty, integrity and full humanity of this wonderful population.
We need to stop scaremongering about autism. If you have an autistic child, it's very likely they can lead a lovely life - of varying sorts, if found, evaluated correctly, and enabled and supported properly. I've seen too many parents brought to absolute hysteria about 'all autistic people are dribbling wrecks incapable of doing more than crayoning, who will live in nappies forever!!'. Not a pleasant way to describe anyone, let alone with such inaccuracy. Just rude, really.
That scaremongering is costing a lot of lives, in missed vaccinations, in forcing autistic people to live under-employed and undervalued lives in the margins instead of as welcome and loved people. In forcing people to be less than they can be.
Let's do better, eh? We can. And we will, together.
PS - further research on how many autistic people may have a lower IQ? Only feel comfortable hearing statistics supported by non-autistic-led charities? The National Autistic Society's preferred journal, Autism, wrote about this study
https://journals.sagepub.com/doi/abs/10.1177/1362361316682621?journalCode=auta which shows about a quarter of the autistic people had an IQ lower than 70. Not half. A quarter. Does an IQ lower than 70 mean people can't live independently or communicate? Nope. Most can do so just fine with a small amount of support, according to Government and charity data.