What is Autism? The Basics of Autism Spectrum Condition

Autism spectrum condition (ASC) is a neurodevelopmental condition that means that autistic people have different brains than allistic people.

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Feb 21, 2019

Tiimo member

February 21, 2019
Anna Fay Hermandson
Writer, Lead on partnerships & Community outreach

Quick facts ⬇️

  • ASC is a brain difference that impacts brain anatomy, functioning, and connectivity, which taken together, inform how autistic people experience the world. It is not an illness.
  • People on the autistic spectrum have the same range of intellectual functioning and language abilities as allistic people.
  • It is estimated that 1 out of 160 children has an autistic spectrum disorder, though recent studies report a significantly higher number.
  • At least a quarter of autitic children go undiagnosed. New research actually suggests that this number is much higher and many people go undiagnosed through adulthood.

What is autism?

Autism spectrum condition (ASC) is a neurodevelopmental condition. ASC affects brain anatomy, functioning, and connectivity throughout the life of autitsic people. Autistic people have different brains than neurotypical people, meaning that they experience the world differently.

The presentation of ASC is extremely diverse and, despite stereotyped and oversimplified media representations, individuals along the spectrum have the same range of intellectual functioning and language abilities as allistic (non-autistic) people. Autistic people often have differences from allistic people in terms of communication, sensory processing, executive function, motor skills and coordination, and differences in social interactions.

Often, autistic traits first present during the developmental period, typically in early childhood (1). It is estimated that 1 out of 160 children is on the autistic spectrum, though recent studies suggest a higher number (4). Boys are four times more likely to be diagnosed with ASC than girls (2). This imbalance is likely related to both biological differences, as well as under- or mis-recognition of autism in women and girls, due to gendered social norms and biases in autism research.

Until recently, experts talked about different types of autism, such as Aspergers, Pervasive developmental disorder (PDD-NOS) and autistic condition. With the new ICD-11, the different types have been gathered under the term “autism spectrum disorders”. Many people in the autistic community prefer using autistic spectrum condition or Autistic, to communicate the reality that autism is not an illness; but instead a difference in brain structure and thus, identity and experience. This is why we’ve also chosen to use ASC and identity-first language here.

'Autism is a developmental disability that affects how we experience the world around us. Autistic people are an important part of the world. Autism is a normal part of life, and makes us who we are.’

Causes of autism

ASC is a heritable condition. Genes inherited from one or both parents can impact the development of an autistic brain. The particular way that genetics impact the development of an autistic brain is not well understood (3) and certain environmental conditions probably impact the formation of an autistic brain. Diversity has always been important to human survival, and neurodiversity - the diversity in people’s neurotypes and the consequent diverse ways of seeing the world - is a key part of this. As the Autistic Self Advocacy Network writes ‘Autism is a developmental disability that affects how we experience the world around us. Autistic people are an important part of the world. Autism is a normal part of life, and makes us who we are.’

How is Autism diagnosed?

It isn’t easy to diagnose ASC, though the diagnosis process varies significantly depending on age and healthcare system. However, the process is usually based on a combination of observations and clinical interviews that assess different factors like communication, social interaction, and repetitive behaviours and/or interests. Due to long waits for diagnosis, as well as systemic racist, sexist and ageist bias in diagnostic processes, more and more autistic people are choosing to self-diagnosis and then find online and in-person communities and seek out peer support and other support strategies that way.

Support for Autistic people

Though autism is diagnosed, ASC is a brain difference not an illness. Autism acceptance - of oneself and by one’s community - is so important that it has been shown to be a significant protective factor in mental health, particular depression (7).

Some studies showing improvements of autistic traits that impact quality of life through diet, routines, and certain therapies like Cognitive Behavioral Therapy and Music therapy (6). Alternative communication methodologies (like PECS and/or sign language) have been shown to improve quality of life for some autistic people. Routines play an important role in the daily lives of many autistic people.

It is increasingly accepted that challenges that many autistic people face are caused and/or exacerbated by the conditions of our society that is not built around the needs of autistic people - like the lack of understanding (both interpersonally and institutionally) about the needs of autistic people and the problematic (and sometimes downright harmful) therapy. Accommodations are changes in an autistic persons’ environment that mean a person's access needs are met.

Autistic people are an incredibly diverse group (remember the spectrum is more like a pentagonal colour wheel than a spectrum - see this incredible comic that tries to illustrate how multi-faceted the spectrum really is!), so if you’re supporting someone who’s autistic, ask them!, or if you’re autistic and looking for different support tools or therapies, check out the Autistic Self Advocacy Network or Spectrum News.


  1. ICD-11 for Mortality and Morbidity Statistics, World Health Organization. Retrieved from https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/437815624.
  2. Baron-Cohen, S. (2017). The Genetics of Autism, Autism Research Centre. Retrieved from http://docs.autismresearchcentre.com/papers/2017_Warrier_The-Genetics-of-Autism.pdf.
  3. Ecker, C., Bookheimer, S.Y. and Murphy, D.G.M., (2015). Neuroimaging in autism spectrum disorder: brain structure and function across the lifespan. The Lancet Neurology, 14(11), 1121-1134. https://doi.org/10.1016/s1474-4422(15)00050-2.
  4. Questions and answers about autism spectrum disorders (ASD), World Health Organization. Retrieved from https://www.who.int/features/qa/85/en/. Symptoms Autism, nhs.uk, https://www.nhs.uk/conditions/autism/symptoms/.
  5. Soke G.N. et al. J. Autism Dev. Disord. 48, 2663-2676 (2018)
  6. Jaarsma, P. (2014). Reflections on Autism: Ethical Perspectives on Autism Spectrum Disorder in Health Care and Education. Linköping Studies in Arts and Science no. 606. Retrieved from https://www.diva-portal.org/smash/get/diva2:696956/FULLTEXT01.pdf.
  7. Cage E, Di Monaco J, Newell V. Experiences of Autism Acceptance and Mental Health in Autistic Adults. J Autism Dev Disord. 2018;48(2):473‐484. doi:10.1007/s10803-017-3342-7

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