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)
So, about 2% have an intellectual disability. There's a lot of difference in skills, in that group. Normally professionals divide that 2% into four groups. The standard groups are mild and moderate, which is nearly all of those with intellectual disabilities. And then severe & profound, which is a very small number of people indeed. Every one of them worth care, consideration, being heard, being safe, and having a full set of human rights and proper support. We learn, then, that most people with an intellectual disability can read and write. But we're routinely told that people with intellectual disabilities cannot possible understand or respond to simple questions. Odd.
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. 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. (40%) So, the percentage 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 it 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 an intellectual disability. We can assume that most of those are able to read and write, because we already know that most people with intellectual disabilities fall into the mild/moderate band.
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. Or were routinely told they couldn't possibly be autistic, and turned away by the first professional they saw.
Then, there's how we measure IQ for autistic people. We'd often been using the wrong tests, it seems. 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. Have we been accidentally putting a lot of autistic people into the 'intellectual disability' group when in fact their IQ is pretty normal?
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 young 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. 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. Autistic people who can read and write are routinely told that there is a mythical 30-50% of autistic people who cannot communicate at all. And, on that basis, anything we say is only representing one of two more-or-less equally big groups of people. Mmm. Every person needs enabling to communicate, and the needs of each person matter. But we don't need to invent huge numbers of profoundly intellectual disabled autistic people, do we.
We need to get a grip of what autism is, and is not. It's not a learning disability, although some also have a learning disability. And we need to move firmly into 2021. A 2021 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. Incidentally, autistic people are no more likely to be incontinent than anyone else, and an awful lot of adult women in the general population have degrees of incontinence, for example. Are they leading awful lives? Generally not. Though it would be great if science could do more to assist, of course.
That scaremongering is costing a lot of lives, 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. In routinely underestimating what many can do. In routinely ignoring any of us who are able to communicate, in a quest to believe that 'real autistic people' cannot do so.
Every autistic life is a life of full worth.
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.