Autism is a developmental difference, not a disease — and the support that helps is well-established.

Autism spectrum disorder (ASD) is a neurodevelopmental difference characterised by persistent challenges in social communication and the presence of restricted, repetitive patterns of behaviour, interests, or activities. Both features must be present from early childhood and must cause meaningful functional difficulty for the diagnosis to apply. The current diagnostic frameworks — the DSM-5-TR and ICD-11 — treat autism as a single spectrum, recognising that presentation varies enormously from one autistic child to another.

What “spectrum” actually means

The shift from older sub-categories (autistic disorder, Asperger’s syndrome, PDD-NOS) to a single “spectrum” was a deliberate clinical decision in the 2013 DSM-5. It reflected the strong research evidence that drawing sharp lines between sub-types was not clinically useful — the underlying mechanisms appear continuous, not categorical. In practice, this means that two children who both have autism may look quite different from each other. One may be highly verbal and academically advanced, with social difficulties most visible in nuanced peer relationships. Another may have minimal verbal communication and need substantial support across daily activities. Both meet the diagnostic criteria; both belong on the same spectrum.

How common is autism

Global prevalence estimates have risen substantially over the past two decades, primarily reflecting better identification rather than a true increase in incidence. The CDC’s ADDM Network places US prevalence at about 1 in 36 children. Indian community-based studies have produced lower estimates — typically in the range of 1 in 100 to 1 in 125 — though these likely under-identify autistic children, particularly girls, children with co-occurring intellectual disability, and children in non-metro settings where screening reach is limited.

What causes autism

The current scientific consensus is that autism is predominantly genetic, with heritability estimates from twin studies typically falling between 60 and 90 percent. Hundreds of genes have been linked to autism risk; in most cases, no single genetic cause is identifiable. A small number of environmental contributors — notably advanced parental age and certain prenatal exposures — appear to add modest risk.

Vaccines do not cause autism. The 1998 paper proposing this link was fraudulent, was retracted in 2010, and has been disproven by every replication attempt at scale.

How autism is diagnosed

Diagnosis is clinical — not based on a blood test, brain scan, or genetic test. A developmental paediatrician or child psychiatrist combines (1) developmental history from parents and caregivers, (2) direct observation of the child using standardised tools (most commonly ADOS-2), and (3) review of the child’s functional level across communication, social interaction, and behavioural domains. Where appropriate, formal cognitive testing and adaptive-functioning assessment (Vineland-3) are added.

The AAP recommends universal autism-specific screening of all children at the 18 and 24-month well-child visit, using the M-CHAT-R/F. This catches a meaningful proportion of autistic children at an age when intervention is most plastic. Children who screen positive are referred for diagnostic assessment.

What good support looks like

The strongest evidence supports comprehensive, multi-modal early intervention — typically combining speech-and-language therapy, naturalistic behaviour-analytic intervention (ABA done well), occupational therapy where sensory-motor needs are present, and structured parent coaching. The intensity, mix, and duration of intervention should be calibrated to the child’s profile and recalibrated regularly as the child develops.

Support that is not well-supported — and in some cases is actively harmful — includes nutritional or biomedical “cures”, chelation, and intervention models built on the goal of making a child appear non-autistic at the cost of suppressing the child’s own communication or self-regulation strategies. These are widely available in India and elsewhere; we recommend caution.