Methods to Diagnose Autism in Children

An accurate, timely autism diagnosis is one of the most important things a child's family can have — not a label, but a key that opens the door to appropriate support, therapy, and genuine understanding of the child's inner world.

Early Warning Signs by Age

The earliest signs of autism can appear in infancy, though they are often subtle enough to be missed or attributed to individual variation. Understanding the developmental milestones at different ages helps parents and paediatricians know when to investigate further.

In the first 12 months, signs that warrant attention include limited or absent eye contact, not smiling in response to a smile by 6 months, not responding to their own name by 10–12 months, absence of babbling by 12 months, and limited use of gesture such as pointing or waving. It is important to note that these signs are not diagnostic on their own — but the presence of several together is a strong reason to pursue evaluation.

Between 12 and 24 months, the key milestones to watch are the emergence of single words by 16 months and two-word phrases by 24 months. Loss of previously acquired language skills at any point — known as regression — is always a red flag and requires immediate investigation. Other signs in this age group include limited pretend or imaginative play, unusual attachment to specific objects, and distress at changes in routine.

From age 2 to 5, the picture often becomes clearer. Autistic children in this age group may show rigid adherence to routines, repetitive behaviours (hand-flapping, rocking, lining up objects), intense and narrowly focused interests, sensory sensitivities (to sound, light, texture, or smell), and difficulty with social interactions with peers. Language, when present, may be scripted, echolalic (repeating phrases heard elsewhere), or unusually formal for the child's age.

Who Makes the Diagnosis

Autism diagnosis in India is most reliably made by a developmental paediatrician, a child and adolescent psychiatrist, or a clinical psychologist with specific training and experience in autism assessment. General practitioners and paediatricians can and should screen for autism and make appropriate referrals — but formal diagnosis requires specialist evaluation.

Major public centres in India with established autism assessment services include NIMHANS in Bangalore, KEM Hospital in Mumbai, and the Child Development Centre at AIIMS Delhi. In Pune, several private developmental paediatricians and child psychiatry services offer comprehensive assessment. For families in Kharadi and surrounding areas, we can provide specific referral guidance at consultation.

It is worth being aware that waiting times for assessment can be long in the public sector. If you have concerns, begin the referral process early rather than waiting to see if the child "grows out of it." Private assessment, while costly, can reduce waiting time significantly in urgent cases where delay would affect intervention timing.

Diagnostic Tools Used in Assessment

Autism diagnosis is not made by a single test. It relies on clinical observation, developmental history, and standardised assessment tools used in combination. Each tool contributes a different piece of the picture.

The M-CHAT-R/F (Modified Checklist for Autism in Toddlers, Revised with Follow-Up) is a parent-report screening tool used at 18 months. It is not diagnostic but identifies children who require further assessment. The Childhood Autism Rating Scale (CARS) is a 15-item clinician-administered scale that rates the severity of autistic traits across domains including social interaction, communication, and adaptive behaviour.

The gold standard for autism diagnosis is the ADOS-2 (Autism Diagnostic Observation Schedule, Second Edition) — a structured, play-based observation by a trained clinician that directly assesses social communication and restricted/repetitive behaviour across five modules calibrated for different language and developmental levels. It is typically used alongside the ADI-R (Autism Diagnostic Interview, Revised), a detailed parent interview covering the child's developmental history. Together, these two instruments provide the most reliable basis for diagnosis currently available.

The DSM-5 Diagnostic Criteria

The current international standard for autism diagnosis is the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition). It defines autism spectrum disorder across two core domains: persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behaviour, interests, or activities. Both domains must be present from early development, though they may not become fully apparent until social demands exceed the child's capacities.

The DSM-5 also defines three severity levels based on the degree of support required: Level 1 (requiring support), Level 2 (requiring substantial support), and Level 3 (requiring very substantial support). These levels are not fixed — a child's functional level can change significantly with appropriate intervention, and many children initially assessed at Level 2 or 3 move to Level 1 with early, intensive therapy. The severity level is a description of current need, not a prediction of lifelong outcome.

Co-occurring Conditions to Assess

Autism rarely presents in isolation. A comprehensive assessment should also evaluate for co-occurring conditions that are common in this population and that significantly affect functioning and quality of life. ADHD is present in 50–70% of autistic individuals; anxiety disorders are extremely common, particularly in children with higher cognitive ability who are more aware of their social difficulties. Intellectual disability co-occurs in approximately 30–40% of autistic children, though this figure has been revised downward in recent years as assessment tools have improved.

Epilepsy affects approximately 25% of autistic individuals, with a bimodal peak of onset in early childhood and adolescence — an EEG may be warranted particularly in children with regression or unusual episodes. Gastrointestinal disorders (constipation, food intolerances, inflammatory gut conditions) are present in 70–90% of autistic children and contribute significantly to behavioural distress. Sleep disorders affect 50–80% and warrant specific attention, as chronic sleep deprivation worsens every other symptom.

After the Diagnosis: Next Steps

Receiving an autism diagnosis for your child is the beginning of a process, not an endpoint. The immediate practical steps include building the multi-disciplinary support team described in our companion article (speech therapy, OT, behavioural therapy), connecting with parent support networks, and informing the child's school to activate educational support provisions.

From a homeopathic perspective, the post-diagnosis period is an appropriate time for a constitutional assessment. We take a comprehensive developmental, medical, and constitutional history — covering prenatal factors, birth history, the child's characteristic sensory sensitivities, emotional state, sleep and digestive patterns, and physical constitution. This informs the constitutional remedy selection, which addresses the underlying state rather than the diagnostic label.