• Question: I had a conversation with a teacher friend today, and she said that among her friends more than 50% have a child that's autistic. That differs greatly from my experience, as I know only 1 person with an autistic child. Are there regional differences in the rates, and where can these kind of statistics be accessed? Have there been any advances in understanding (even possible) causes of autism?

    Asked by Abena to modkathryn on 24 Apr 2018.
    • Photo: Kathryn Bates

      Kathryn Bates answered on 24 Apr 2018:


      Hi there, these are both really interesting questions!
      The National Autistic Society UK website is a great resource for all things autism. See link here: http://www.autism.org.uk/about/what-is/myths-facts-stats.aspx
      On their facts and history page they state that in the UK around 700,000 are currently diagnosed with autism which about 1 in 100.
      In terms of prevalence, studies tend to be carried out per region, e.g. Cambridgeshire, which is usually because a national study would be very costly. And even in the large scale studies, these samples quite often don’t include those living in residential care or those with learning disabilities too severe to allow them to participate (see here for more info: http://www.autism.org.uk/get-involved/media-centre/news/2016-09-29-prevalence-figures.aspx)
      However, these prevalence studies can still be very useful even though their cohorts may seem restricted. The findings can be compared to other regional studies and can be used to estimate overall prevalence – after all, its impossible to get everyone in the country to participate in any given study!
      As far as I can see, comparisons between prevalence studies carried out in different areas show there are minimal regional differences (see here for more info: https://s3.amazonaws.com/academia.edu.documents/42643623/500.full.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1524490729&Signature=wXZ%2Bl9Q8NYyfNIg75A%2BLio3J2zk%3D&response-content-disposition=inline%3B%20filename%3DPrevalence_of_autism-spectrum_conditions.pdf)
      Others have found some variation in regional rates but have found that this is stable over time (see more information here:
      http://bmjopen.bmj.com/content/3/10/e003219
      This study is quite interesting because in the discussion section they consider the differences in rates in relation to events happening at the time, such as the whole MMR vaccine/autism scandal that has since been proved to be completely false (see here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136032/).

      As is the case in most developmental disorders (apart from genetic disorders such as Downs syndrome), there is no single cause of autism and this is a very complex question. Research trying to identify the causes of these disorders tends to start by identifying risk factors, for example what are the risk factors that are associated with a diagnosis of autism? Some research has identified genetic risk factors; however this tends to include multiple genes (there is no single gene for autism) (see reference here: https://www.nature.com/articles/nrn.2016.184.pdf?origin=ppub )

      There may also be environmental triggers, for example as birth complications involving trauma and/or advanced parental age have been associated with increased risk (see reference here: https://molecularautism.biomedcentral.com/articles/10.1186/s13229-017-0121-4 ) “Associated” is the keyword here because it cannot be concluded any one of these factors is the single cause, and “risk” is also important because some individuals may experience these complications but will not develop the disorder. However, what this does tell us is that being exposed to an identified risk factor is associated with higher likelihood of developing this disorder.

      Identifying both genetic and environmental risk factors is really useful in this research as it can inform diagnosis and may allow for intervening early. There is currently a large-scale study called the British Autism Study of Infant Siblings being conducted looking at identifying early signs of autism in infants which can reveal more about when and how to intervene. Here is the link to the website:
      http://basisnetwork.org/

      I hope this is useful and somewhat answers your questions! – if any of the links don’t work please let me know and I’d be happy to send a pdf. Feel free to ask any follow up questions to anything I’ve outlined.

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