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expert reaction to meta-analysis of studies comparing individuals with and without autism over time

Research, published in JAMA Psychiatry, reports that the differences between individuals with autism and those without autism have decreased over time, which may be associated with changes in diagnostic practices. 


Prof Uta Frith FRS FMedSci, Emeritus Professor of Cognitive Development, Institute of Cognitive Neuroscience, University College London (UCL), said:

“Mottron and colleagues have provided strong evidence and put into words what autism researchers, especially those studying cognitive mechanisms, have been feeling for some time: belief in an autism spectrum has led to a dilution of what we mean by autism. It is particularly interesting that this dilution has not happened for schizophrenia. One reason might be that here, some of the symptoms were defined in such a way that they could be seen as far away from normal experience. The effort in autism has gone into the opposite direction, possibly a side effect of a well-meaning attempt to eradicate stigma. If you think that you can be ‘a little bit autistic’, then it is hard to hold on to the idea that autism is a natural entity, with a genetic basis that leads to abnormalities in brain development.

“But people can’t be ‘a little bit autistic’ and not everything is on a continuum. Scores you get on tests that tap a particular ability are on a continuum, but that does not mean that the reason for getting the scores is the same. An example is weight, a continuous measure, but being overweight can have many different reasons. Some people are overweight because of an endocrine disease, but you can’t say that somebody, who is overweight is having a little bit of, say, Cushing’s syndrome.

“It is now vital to study subgroups of the autism spectrum for progress to be made. Big data is not the solution.”


Dr Punit Shah, Psychology Lecturer, University of Bath, said:

“This is a critically important piece of research, which brings together many decades of research on autism. The authors use a robust methodological approach often lacking in autism research, with a sharp focus on the research and medical implications of their findings.

“I support many of the authors’ conclusions and recommendations for the diagnosis of autism in future. In particular, there is growing confusion around diagnostic terminology – moving away from autism, towards “autism spectrum conditions”, and a growing failure to use the terms laid out in diagnostic manuals. Similarly, there is a strong agenda to remove mention of “disorder”, “impairments” and even “difficulties” when researching autism, with a view of reducing societal stigma. Unfortunately, this watering down of language pertaining to autism generates serious confusion among clinicians and the general public, often resulting in the ‘trivialization’ of autism that the authors describe. We need to be mindful of terminology such that it isn’t offensive and causing stigma, but not at the cost of scientific rigour or confusion in clinical practice.

“With that said, I disagree with Dr Mottron’s final statement that “No major discoveries have been made in this field in the last 10 years.” We have a long way to go, but there is some remarkably good autism research in progress, showing which psychological abilities are impaired, intact, and even enhanced in autism. And the suggestions from the study by Rødgaard et al. will hopefully improve this research.”


‘Temporal Changes in Effect Sizes of Studies Comparing Individuals With and Without Autism’ by Eya-Mist Rødgaard et al. was published in JAMA Psychiatry at 16:00 UK time on Wednesday 21st August. 

DOI: 10.1001/jamapsychiatry.2019.1956


Declared interests

Prof Uta Frith: I have no conflict of interest to declare. I have not been involved in the study.

Dr Punit Shah: No declarations of interest.

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