Overview
Autism spectrum disorder (ASD) is a neurodevelopmental condition affecting how a person communicates, interacts with others, and experiences the world. The word 'spectrum' reflects the wide range of abilities and challenges. Autism is not an illness to be cured; it is a different way the brain develops and processes information.
How common is it?
Autistic people have a wide range of strengths and support needs. Autism may be recognised in childhood or later in life, and can be harder to recognise in women and girls.
Causes and risk factors
Autism involves differences in early brain development. Genetic factors play an important role, and the causes are not fully understood. It is not caused by vaccines or parenting style. Certain prenatal exposures, including valproate, can increase neurodevelopmental risks; discuss medicines with a specialist before pregnancy and never stop prescribed treatment on your own.
Common risk factors
- Genetic factors (strong heritable component)
- Advanced parental age
- Premature birth
- Genetic conditions such as Fragile X syndrome
- Certain medications taken during pregnancy (e.g. valproate)
- Autism can run in families; having an autistic relative can increase likelihood
Symptoms
- Difficulty understanding or using non-verbal communication (facial expressions, gestures)
- Preferring routine and becoming distressed by unexpected changes
- Intense, highly focused interests in specific topics
- Difficulty reading social situations or understanding unspoken rules
- Sensory sensitivities: over- or under-reaction to sounds, lights, textures, tastes
- Taking language very literally
- Repetitive movements such as rocking or hand-flapping
When to see a doctor
Ask your GP for an assessment referral if you are concerned about social communication, repetitive behaviour, or sensory differences in a child or in yourself as an adult. Early support makes a significant difference.
Diagnosis
Diagnosis involves structured observations and interviews with specialists (often a child psychiatrist, psychologist, and speech therapist working as a team). In adults, a detailed developmental history is taken. There is no blood test or brain scan for autism.
Treatments
Speech and language therapy
Supports communication skills, including understanding and using spoken language, non-verbal communication, and social interaction.
Occupational therapy
Helps with sensory processing, daily living skills, and adapting environments to reduce overwhelm and support independence.
Educational and behavioural support
Structured teaching approaches, support in mainstream or specialist school, and strategies for managing anxiety and change help autistic people thrive.
Self-care and lifestyle
- Predictable routines and visual schedules reduce anxiety
- Reduce sensory overload by adapting environments (noise-cancelling headphones, dimmer lighting)
- Connect with the autistic community for peer support and practical strategies
- Look for autism-friendly employers, social groups, and services
Prevention
There is no proven way to prevent autism. The focus is on understanding each person's needs and providing appropriate support. Before or during pregnancy, review medicines with a clinician to reduce avoidable harms; do not stop prescribed medicines yourself.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to causes, risk factors, prevention, frequency. This update covers the named sections; a full review of the remaining guide is pending.