What is autism?
How to make sense of autism beyond the stereotypes.
Published 23 June 2025. Written by Leeds Autism Practice Staff.
What exactly is autism? It’s a more complex question than it might first appear — and one that’s still evolving. In this article, we will explore how autism is defined, both medically and from a neuroaffirmative perspective.
Our definition
We work from a neuroaffirmative perspective, which means we don't believe there is something "wrong" with autistic people. Where others see deficits, we see differences, to be welcomed, celebrated, and accommodated.
Key features we look for:
- Differences in social communication such as the way we express emotion, engage in conversation, and build and maintain friendships.
- Differences in behaviour and interests such as a preference for routines, repetitive movements (stimming), and an intense focus on specific passions.
- Differences in sensory processing, such as being unusually sensitive or less responsive to things like light, sound, taste, or internal sensations.
For a breakdown of what these differences might look like in real life and how you might recognise them, see our article "How do I know if I am autistic?"
Fundamentally, then, autistic individuals process information differently from neurotypical people.
This can cause challenges in understanding neurotypical people's emotions, reactions and unwritten social rules. The same applies to neurotypical individuals trying to understand autistic people, but as most people are neurotypical, this places more of a burden on autistic individuals.
As a result, autism has historically been seen as a disorder or a medical condition, and we will explore these definitions below.
ICD-11
The International Classification of Diseases (ICD) is one of the two main textbooks used to classify medical conditions and is published by the World Health Organisation. It uses the following definition:
"Autism spectrum disorder is characterised by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication, and by a range of restricted, repetitive, and inflexible patterns of behaviour, interests or activities that are clearly atypical or excessive for the individual’s age and sociocultural context."
In simpler terms, this means difficulties with social connection and communication, along with repetitive behaviours or routines that are noticeably different from what’s typical for someone’s age or background.
The ICD goes on to say these must be lifelong issues and that they cause significant impairment in the individual's life. It also makes references to sensory differences.
DSM-5-TR
The Diagnostic and Statistical Manual of Mental Disorders (DSM) is published by the American Psychiatric Association and is the other main textbook used for classifying psychological mental health conditions.
The DSM requires difficulties in two areas:
- Persistent deficits in social communication and social interaction
- Restricted, repetitive patterns of behaviour, interests, or activities
Again, it says they must be lifelong and cause significant impairment in an individual's life.
It also says that the issues are not better explained by a learning difficulty (intellectual disability). An autistic individual can have a learning difficulty as well, but most autistic individuals do not.
Lifelong nature
Everyone agrees that autism is a lifelong condition. Or, to put that in neuroaffirmative language, it is a neurotype and is part of who a person is. It is not something that can be "cured" in the same way an anxiety disorder might be.
Autism can sometimes be detected in early childhood. But not always. Many children find they can fit in (known as masking) and signs of autism only emerge at high school, or later in life, as social demands become more complex and their coping strategies become overwhelmed.
Is autism a disability?
Most people regard autism as a disability.
For some, this is because autism presents as a set of objective deficits. But even from a neuroaffirmative approach, autistic individuals have to live in a world predominantly designed for, and populated by, neurotypical people. Thus creating significant additional challenges for autistic individuals.
We use a neuroaffirmative approach when assessing for autism. However, we still we compare your experiences to the medical criteria. This ensures that your identification (diagnosis) is recognised by services and professionals who rely on clinical definitions.
Is autism a boy thing?
No. Previously, some researchers have described autism as an "extreme male brain" and even today, the myth remains that autism is much more prevalent in boys than it is in girls.
There are multiple reasons for this. See our article "Autism in women and girls" for a full breakdown.
You may also want to read our article "Myths about autism" where we tackle other myths including autistic people lack empathy, autistic people are unsociable, and many other mistaken ideas.
Summary
Autism is a difference in the way individuals process information. Autistic individuals show differences in social communication, patterns of behaviour and sensory profiles. These differences are lifelong and can create challenges in a world designed for neurotypical people.
Understanding autism as a difference — not a defect — helps create a more inclusive world where all neurotypes are recognised and valued.