Is autism a category or a dimension?

Since publishing this blog two days ago there has been a very large response on twitter with a lot of autistic people kindly taking the time to feed back on the content. A lot of this has been very positive and all of it has been fascinating, but some people have also fed back to me that they felt the topic of the blog and the specific language used is dehumanising.

I want to take this opportunity to offer a full and unreserved apology to those people and anyone else negatively affected by the blog.  I did offer to take it down but have been encouraged (by the same autistic people, and others) to keep it up and I certainly don’t want to hide my mistake. So I’m posting this here, at the start, not only to apologise but also as a content warning to future readers.

I think it is best to keep this apology relatively short so as not to recapitulate the mistakes and assumptions made in the original post but I think it is worth mentioning a couple of specific things. First, the original question posed by the blog was motivated very much by the fact that I’ve seen so many autistic people angered by measures such as the Autism Quotient (which are used to argue for a dimensional continuum that connects autistic and neurotypical people by varying degrees of “traits”) and also by comments such as “everyone is a little bit autistic”.  Also, how the clinical definition of autism is conceived of by psychologists, psychiatrists and other disciplines involved in diagnosis has a big impact on how autistic people are understood in clinical services and I wanted to inform that debate a little. My intention was never to make autistic people feel “alien” though I can see why that happened and I am sorry for it. Second, I want to apologise for some of the use of language in the blog which increased the negative impression.  I talked a bit about “autism” in an abstracted way which de-centered autistic people and their experiences. I also used metaphors which had unintended negative consequences. I spent a long time selecting between metaphors in an effort not to have this effect and I’m just very sorry that I didn’t find a better way to express what I was trying to say. For example I considered using the metaphor of ice and water – the same things just in different states of being – but was worried about the possibiity that this might evoke the idea that neurotypical people could become autistic or autistic people could become neurotypical by a (metaphorical) process of melting / freezing. I rejected this metaphor and settled on coffee and tea (both hot drinks, both caffeinated) and it simply didn’t occur to me that their lack of a common ancestor would increase the sense of alienation for autistic readers. I am very sorry for this.

I hope all my readers know that I never mean to do harm and work hard to understand better when I make mistakes. I am grateful to all the autistic people who take the time to set me straight.  If you are still curious about the blog please do read on. 

For some incomprehensible reason I offered on twitter to write a blog post about this topic, months ago, and the June Blogs series means I guess I can’t avoid it any longer.

The reason I might want to avoid it is that I don’t think there is a good answer to this question and I also think that trying to discuss it is potentially a minefield.  But I do also think it is a truly fascinating question, as well as one with practical importance.

Before I explain that though, let’s just quickly summarise the distinction between a category and a dimension – at least as I think it applies to autism.

If autism is a category that means autistic people are quite fundamentally different from neurotypical people º. Perhaps a good metaphor would be coffee and tea.  They’re both hot drinks, but they’re fundamentally different from each other – you can’t make such a strong cup of tea that it actually becomes a cup of coffee.  Both of them might taste better with milk and worse with sugar, but that similarity doesn’t mean the underlying drinks are the same.

If autism is a dimension then the appropriate beverage metaphor might be more like different kinds of coffee.  The ingredients are the same and the difference is really just the degree to which each ingredient is expressed.  Perhaps autistic people are flat whites and neurotypical people are cappucinos. If you add enough hot air to an autistic person, they become neurotypical.*

Why should we care about this question?

Well, lots of reasons.  One is that understanding whether autism is a category or a dimension is relevant to debates about whether people can claim to be “a little bit autistic”. This is not only tiresome for autistic people but makes a big difference when it comes to autism research – and specifically to the question of whether research that examines trait distributions in the general population (non-autistic and presumably majority neurotypical) can tell us anything about autism.  If being autistic is dimensionally, and not categorically, different from being neurotypical then understanding how – for example – response to a mindfulness intervention relates to autism trait scores in the general population would have implications for autistic people too.  If neurotypical people with high levels of autism-traits (there’s more on this concept of “traits” below) really benefit from a mindfulness intervention, then it might be something good to recommend to an autistic person too. But if autism is categorically different from neurotypicality, then that recommendation would have a flimsy basis at best.

Another reason why this matters is that whether we understand autism as a dimension or as a category could shape how we think we – as a society – should respond to the existence of autistic people. If we think autistic people are only separated from neurotypical people by a matter of degree, we might be tempted to try to make autistic people more neurotypical, by working away at specific “traits”.  We might allow ourselves to believe not only that it is possible to train someone to be, for example, “more socially skilled” but also that it is desirable.

A simplistic, but hopefully instructive, parallel might be to consider how a physiotherapist would approach a patient who wasn’t able to walk. If the lack of walking results from a dimensional difference – perhaps very weak muscles – they would work on that dimensional difference, strengthening the muscles until walking was possible. If the lack of walking results from a categorical difference – like amputation  – they wouldn’t focus on incremental change, they would focus on environmental adaptations, like a wheelchair or artifical legs, to facilitate a step change in opportunity.^  Similarly in the case of autism, dimensional versus categorical models of understanding might lead us down very different pathways in education, healthcare and social services.

I should emphasise now that I know many excellent people who I think believe autism is only dimensionally distinct from neurotypicality, and have absolutely no hint of using this framing as a justification for some sort of therapeutic approach like I’ve just described. But I do think that considering how we conceptualise neurotypicality and autism in relation to each other has implications for practitioners.

Evidence for a dimensional difference

Probably the single biggest bit of evidence that autism and neurotypicality are distinguished dimensionally comes from the diagnostic process.  There is no categorical marker of autism – no blood test, no brain scan, no hormone profile, no shoe size – and as such the diagnostic process is more of a quest for signs and clues that this ultimately socially-constructed label “autistic” is the right fit for the person in front of you.

In research, there are a whole host of measures on which autistic people reliably score high (or low, depending on the measure, but we’ll just go with high for the purposes of this blog) and neurotypical people score low or medium. The most famous of these is the Autism Quotient – a measure explicitly created to capture autistic-like traits in the general population. Studies using the AQ frequently show that autistic people score about about 32, but also that their close relatives (parents, siblings) score in the moderately-high range, even if they themselves are not autistic. We definitely know that autism runs in families – not entirely predictably but reliably nonetheless – and so this finding suggests that there is such a thing as being “almost autistic”. The idea is that being “almost autistic” might happen when you have some of the genetic ingredients that tend to lead to autism, but not all of them, so you don’t quite tip over into the clinical category – but you do have a lot of “autistic traits”.

The problem with this thinking is that it assumes that the measures we use are giving us insight into some ground truth, rather than merely dictating the conceptual models we have available. There’s a recursive logic that comes from creation of a dimensional measure of “autistic traits” which is then used – regardless of whether the originators intended or not – as evidence of the dimensional status of autism in relation to neurotypicality.

Evidence for a categorical difference

I find myself having a huge number of questions about dimensional conceptualisations of autism.  One concerns the existence of a sort of opposite autism, let’s call it “nautism”.  If autistic people are the people with the highest levels of autistic traits, at the right-hand-most tail end of the normal distribution of AQ scores – dark blue in this figure – then shouldn’t there also be people at the extreme left of the distribution who are not merely “very not autistic” but actually something else all together? At the moment, it seems to me that we characterise the whole distribution – red, yellow, green, turquoise – as far as the line in the sand that separates off the dark blue autistic section, as neurotypical. But surely the folk in the red zone are just as different from the neurotypical majority as the autistic folk in the blue zone.  You’d expect them also to be struggling by virtue of being different from the norm.  I don’t think we really know anything about who these people are, and that fact makes me doubt that autistic people are only separated from neurotypicals by a matter of degree.

Another issue concernes which measure we are using when we attempt to make this dimensional split between autistic and neurotypical people. After all, autism is defined by a constellation of features – we tell autistic and neurotypical people apart by their sensory responses, their communication preferences, and the intensity of their interests. For many of these features there are dimensional measures – mostly self-report questionnaires – on which autistic people score highly and neurotypical people score in the middle or low range. But it doesn’t make sense, does it? – or not to me – that autism and neurotypicality would be dimensionally separated on so many different, orthogonal metrics.

Let me put it another way.  As a neurotypical person, I might score moderately high on sensory sensitivity, very low on a communication profile measure, and in the middle on intensity of interests. My neurotypical colleague might score moderately high on both sensory and communication measures, but very low on intensity of interests.  My neurotypical neighbour might have a different profile again – but we’re all neurotypical.  Meanwhile every autistic person scores high on all these things, despite being as different from each other in personality, preference, looks and life experiences as myself, my colleague and my neighbour?

The final counterpoint to arguments about dimensionality comes from the lived experience of autistic people. I have never met an autistic person who characterises their experience of the world as being like a neurotypical person but just…. more so. Quite to the contrary.  Although attempts to find common ground are often well meant on the part of the neurotypical person, I think it drives a lot of autistic folk up the wall. My dislike of hand driers is not merely a watered down version of an autistic person’s hyperacusis. My tiredness after a zoom meeting might help me empathise a little better with autistic burnout after social occasions, but it doesn’t mean I have experienced something truly akin to the autistic experience.

Reconciling these accounts?

I do wonder though if there’s a way to reconcile these two accounts somewhat.  I mentioned above that it seems remarkable that all autistic people would differ dimensionally from neurotypical people in so many different domains – sensory, communication, interest etc. Perhaps the category of autism is defined by the intersection of these dimensions.

For this, I think we need a different metaphor. What if each dimension on which we try to plot out the continuum from neurotypical to autistic is like an ingredient in a cake. I might have some eggs and some cocoa. My neighbour has some flour. My colleague has butter and sugar. But none of us have everything – only autistic people have the whole cake. Autism isn’t measured by a score on this or that measure – or by how many eggs or how much sugar someone has – autism requires the presence of the whole cake. It’s a pattern of dimensions that create a category of autism.

 

º I ought to be using autistic and non-autistic in this blog post as opposed to autistic / neurotypical but I’m afraid I really dislike the term non-autistic, not least because I think it impedes reading using two such similar terms that are differentiated only by a prefix. Like saying girl and non-girl which is entirely more inclusive of the gender spectrum, but also not nice to write.  Solutions to this problem (including telling me to get over myself) are very welcome.

* In case it isn’t completely clear, this is intended to be a joke at the expense of neurotypical people, since we are often a bit full of hot air.

^ please forgive me, anyone reading this, for my vast oversimplification of physical therapy here.  I hope the metaphor is helpful even if it is also clunky.