Autism

A neurodevelopmental difference in social communication, sensory experience and patterns of interest: history from Kanner and Asperger, prevalence, genetics, the debunked vaccine myth, brain research and neurodiversity.

What autism is

Autism spectrum disorder (as diagnostic manuals call it) involves differences in social communication and interaction and restricted or repetitive patterns of behaviour, interests or activities, present from early development. It includes sensory differences — being over- or under-sensitive to sounds, lights, textures — which many autistic people describe as central. Support needs vary enormously: some people have intellectual disability and little spoken language; others have average or high intellectual ability.

History

In 1943 the Austrian-American psychiatrist Leo Kanner described 11 children with "autistic disturbances of affective contact". In 1944 the Viennese paediatrician Hans Asperger described boys with social difficulties and intense interests (later research documented his collaboration with the Nazi regime's child "euthanasia" programme). From the 1950s, the false and harmful "refrigerator mother" theory blamed cold parenting. Lorna Wing's work in the 1980s helped establish the idea of a spectrum, and DSM-5 (2013) merged previous categories, including Asperger syndrome, into autism spectrum disorder.

Prevalence

Diagnoses have risen greatly, largely due to broader criteria, greater awareness and better identification of girls, women and adults. The US CDC reported in 2025 that about 1 in 31 eight-year-olds were identified as autistic in 2022 data. More boys than girls are diagnosed, though girls may be under-identified.

Causes

Autism is highly heritable — twin studies estimate around 80%. Hundreds of genes are involved, many affecting synapse formation and brain development, some via new (de novo) mutations. Prenatal factors such as advanced parental age and some prenatal exposures modestly raise risk. Vaccines do not cause autism: the 1998 paper by Andrew Wakefield claiming a link to the MMR vaccine was found to be fraudulent and retracted in 2010, and Wakefield was struck off the UK medical register; large studies of millions of children have found no link.

The brain and neurodiversity

Research has found differences in early brain growth, connectivity, sensory processing and prediction, but no single "autism brain" signature. The neurodiversity movement, led largely by autistic people, frames autism as a natural variation of human neurology that deserves acceptance and accommodation, while recognising real disabilities and support needs. Support focuses on communication, reducing distress, accommodating sensory needs and building on strengths.