A series of programmes on BBC looked into the huge rise in diagnoses of autism in the UK [1]. The programmes gave space for various academics (as well as other professionals) to explain this ‘autism curve’ and speculate as to its consequences. All spoke in a balanced and open manner and you ended up feeling you knew more than you started. So, what were the key points?
Well, the dramatic rise in autism diagnoses seems an established fact. For example, Russell et al found, using data from 9 million users of health services, that there was a near 800 percent increase in autism diagnoses in the UK from 1998 – 2018 [2]. Similarly large increases have been found in other developed countries and in the USA today as many as 1 in 36 have been diagnosed as autistic.
The question then becomes what explains this large increase? The most obvious explanation is that the concept of autism has changed. In the past autism was largely associated with non-verbal or limited speech, profound intellectual disability and repetitive, sometimes erratic behaviour. However, over time the term has expanded, including people who struggle when interacting with others, for example do not follow turn-taking in conversation, or experience stimulation anxiety [3]. These are traits that may lead to persistent difficulties in participating in social life, though much depends on circumstance. For example, autism may particularly affect children in school as they have less agency over their time and activity while in a suitable workplace autistic people could be functioning or even highly functioning. Whatever the case, it is now much more common to think of autism as a spectrum and it is at the lower and middle end of this spectrum that diagnoses have grown rather than at the severe end. Indeed, autism seems to have become de-stigmatised, at least to a degree, and even embraced as a label often through the work of support groups and celebrity endorsement.
A second ways of understanding why the number of diagnoses has gone up lies in the underreporting of autism in the past. In other words, there is not more autism about, we simply did not recognise it before. This seems particularly the case with females. Autism was strongly associated with males, largely because the pioneering work of Kanner and Asperger was carried out with male children. This shaped the discourse and the link between males and autism became almost self-fulfilling. Consequently, females were often undiagnosed or diagnosed wrongly. One aspect of this underreporting is that older people are often diagnosed as having dementia or ‘memory problems’ when it is their autism that has come to fore as they lose supportive partners. Further, there has also been underreporting of autism among ethnic minority children both because behaviour was stereotyped as ‘typical of children of their background’ but also because of a sense of shame in some cultures surrounding disability.
At this point we can ask what causes autism? Experts were clear that that the most probable explanation was genetic. However, it was important to realise that they were talking about probabilities not certainties, in other words children with autistic parents are more likely to be autistic but you cannot say that autism will necessarily be passed on. Other, less scientific, explanations have been put forward. Indeed, one contributor had found over 100 suggested causes including complications during pregnancy and during birth, toxins in the environment, ultra processed food, chemicals and general pollution and so on. These explanations were weak but could not be dismissed out of hand, and in particular experiences of pregnancy and childbirth may play a role. Experts were agreed that Wakefield offered one of the most damaging explanations when in 1998 he linked autism to the measles, mumps, and rubella (MMR) vaccine [4]. One possible reason why this quite erroneous connection gained traction was that autistic traits were more likely to be identifiable at around 18 months and this was the age at which the MMR vaccine was given.
So we are left with the question, if diagnoses have been rising is this a good or bad thing? Well, here medical science can give less secure answers, though cases studies and ethnography can report on the experience of those with autism and the value, or otherwise, of getting a diagnosis. However, we can at least say that the de-stigmatising of autism has helped us understand the extent of neurodiversity in the population. Indeed, in some schools the number of children seen as neurodiverse outnumber those who are neurotypical. You could say here that this broadening of the concept is imposing extra demands on already hard-pressed teachers but you could also argue that schools were wrong to focus for many years on neurotypical students and might have been making life unnecessarily difficult for those who were neurodiverse. In a wider context, broadening the definition of autism may have created an environment in which some are better able to understand their behaviour, including ‘masking’ – the covering up to yourself and others that you are not experiencing events in a neurotypical fashion but only pretending you are. Here, the social influencer, Ellie Middleton, was presented as an example of someone who had understood her behaviour more. She came over as confident, articulate and proactive but she explained she had only become so by understanding the autistic traits that made her earlier life so anxiety-ridden [5].
The programme makers were relaxed about the ‘autism curve’ but they did hint at a danger of losing the focus on the most severely autistic children, i.e. children who are non-verbal, or at least with severe communication difficulties, coupled with intellectual disability. In other words, if autism has become a much looser concept do we now need a different word to capture the most severe end of the spectrum?
References
[1] These were five episodes in the series and they are available until 5 May 2026:
BBC (2005) The Autism Curve [Online] https://www.bbc.co.uk/sounds/play/m002bszl
[2] Russell, G. et al. (2022) Time trends in autism diagnoses over 20 years: a UK population-based cohort study. The Journal of Child Psychology and Psychiatry, 63, 6, 674-682 [Online] https://acamh.onlinelibrary.wiley.com/doi/10.1111/jcpp.13505
Russell’s (2021) book ‘The Rise of Autism Risk and Resistance in the Age of Diagnosis’ London Routledge takes a more general look at the rise in diagnoses.
[3] Successive handbooks of Diagnostic and Statistical Manual of Mental Disorders provide practitioners with classifications of syndromes and DSM-5 in 2022 removed Asperger’s syndrome from a distinct disorder to an autism spectrum disorder.
See also NHS advice for a popular guide to ‘What is autism’ [online] https://www.nhs.uk/conditions/autism/what-is-autism/
[4] The sorry tale of Wakefield’s research is told in many articles including Editorial (2011) Wakefield’s article linking MMR vaccine and autism was fraudulent, BMJ, 342 [Online] https://doi.org/10.1136/bmj.c7452
[5] A previous interview with the BBC explored Ellie’s experiences:
BBC (2023) Ellie Middleton: ‘Learning the way my brain works has changed everything for me’ 17 December 2023 https://www.bbc.co.uk/news/disability-67406374
Michael Hammond 