What is Autism Spectrum Disorder?
Autism spectrum disorder (autism) is a neurological (brain-based) condition that influences the development of social and communication abilities, as well as other aspects of behaviour, in characteristic ways. The term “autism spectrum disorder” (ASD) reflects the current view that how autism affects learning and behaviour ranges from relatively mild to more significant in these areas of development. For example, the pattern of social and behavioural differences that defines autism co-exists with all levels of intellectual ability, although a substantial minority of autistic people have an intellectual disability.
Autistic people face challenges in understanding and relating to other people in typical reciprocal ways. For example, someone with autism may lack a natural grasp of interpersonal skills such as the ability to take another person’s point of view even when interested in social interactions and relationships. Non-autistic people may also find it hard to relate to the perspectives of autistic people. For some autistic people, language difficulties may make it harder to express their ideas. Even when language skills are strong, other differences in communication may affect social situations. An autistic person might have difficulty beginning a conversation or keeping one going in a fluent, two-sided manner. Autism may also be associated with reduced flexibility in thinking and behaviour. Their interests and activities may be intense or focused, which can be either a strength or a liability. For some autistic individuals, differences in sensory responsivity may include over- and/or under-reaction to lights, sounds, touch, tastes, odours, or pain.
Research shows that autism is a complex condition in which genetic, environmental, and societal factors interact; the specific causes are not yet known. The likelihood of developing autism is increased for children born to families who already have a diagnosed family member, and more boys/men than girls/women are affected by autism (although autism is also less often diagnosed accurately in girls and women). In its more severe form, autism is usually recognized by about age 2 years – often because the child is not yet speaking and shows limited interest in people. However, more subtle signs of autism may not be recognized until much later, often during the school years as differences from peers are noticed.
How is Autism Diagnosed?
Autism is diagnosed by an experienced clinician (usually a clinical child psychologist or a specialist physician) based on observed and reported patterns of behaviour. There is no medical test for autism. The diagnosis is made using in-depth information from parents and others about specific aspects of the individual’s development and behaviour, and the clinician’s systematic direct observations of behaviour. These observations cover both what the person does that may be characteristic of autism and doesn’t do that would be expected of a typically developing individual at that age or level of development. A comprehensive evaluation also considers the possibility of other conditions, such as intellectual disability, attention deficit hyperactivity disorder, or social anxiety disorder, that often lead to a suspicion of autism or co-occur with autism.
With earlier recognition in young children and a better understanding of both milder and more severe forms in people of all ages, the diagnosis of autism is becoming far more common. A recent Canadian estimate suggests that at least 1 in every 50 children is affected (Public Health Agency of Canada, 2022). The impact of autism varies, but autistic individuals and their families require health, education, and community services and supports. Many communities are trying to keep pace with the increasing need for autism-related services.
What Do We Do About ASD? Can Psychology Help?
Outcomes for many autistic people are far more positive than in past decades. Factors such as an individual’s levels of ability, presence of other health or mental health conditions, and importantly challenges accessing appropriate supports all contribute to highly variable long-term outcomes for autistic people. Some autistic individuals attain social, academic, and vocational success, as well as independent living, especially as communities become more accepting of neurodivergence.
Advances in psychological research have improved our understanding of the fundamental developmental differences as well as the strengths and challenges of autistic people. Psychologists have contributed to improved methods of recognizing, assessing, and intervening to support those with autism. Psychological assessment of children’s ability profiles – areas of relative strength and weakness – as well as evaluation of both autism characteristics and symptoms of co-occurring conditions can guide the development of appropriate education and therapies for autistic children. Treatments based on psychological principles are at the leading edge of autism intervention.
Early intervention can improve the quality of many young autistic children’s lives when strategies are used that capitalize on natural teaching opportunities in the home and community. Strategies based on the principles of learning can be used within the child’s daily routines with parents as partners in supporting their children’s development. Key areas for intervention usually include language/communication and social skills, daily living skills, self-regulation or coping skills, and family support. Peer-mediated interventions, in which autistic children and their nonautistic peers learn to play and communicate effectively, can promote more positive social opportunities. For older, able autistic individuals, cognitive-behavioural therapy (CBT) strategies can help manage common difficulties with anxiety or self-regulation.
Better access to evidence-based treatment for the mental health needs of autistic adults is needed in most communities. Psychologists and other mental health professionals are increasingly able to customize mental health care for autistic and other neurodivergent people. Community-based supports such as job coaching, recreational opportunities, and supported housing services are beneficial for many autistic people.
Where Can I Go for More Information?
- Autism Alliance of Canada: https://autismalliance.ca/
- National Autistic Society (UK): http://www.autism.org.uk
- Provincial associations of psychology: https://cpa.ca/public/whatisapsychologist/PTassociations
- Psychology Foundation of Canada: http://www.psychologyfoundation.org
- American Psychological Association (APA): http://www.apa.org/helpcenter
You can consult with a registered psychologist to find out if psychological interventions might be of help to you. Provincial, territorial, and some municipal associations of psychology may make available a referral list of practicing psychologists that can be searched for appropriate services. For the names and coordinates of provincial and territorial associations of psychology, go to https://cpa.ca/public/whatisapsychologist/PTassociations/.
This fact sheet has been prepared for the Canadian Psychological Association by Isabel M. Smith, PhD. Dr. Smith is a registered Clinical Psychologist, Professor and former Joan and Jack Craig Chair in Autism Research, Departments of Pediatrics and Psychology & Neuroscience, Dalhousie University. Dr. Smith’s work at the Autism Research Centre at the IWK Health Centre in Halifax NS is focused on children and adolescents with ASD and their families.
Revised: October 2025
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