Autism Test: How to Diagnose Autism Early

Autism Spectrum Disorder: Screening, Tests and Diagnosis

The screening and diagnosis of autism spectrum disorder (ASD) can be a little difficult. This is due to the nature of the disorder as well as the fact that there are no medical tests available for it.

For example, unlike blood tests, where an ailment can be detected in the blood cells, autism cannot be tested easily.

Healthcare professionals look through and analyse an individual's development history and behaviour to screen and diagnose autism.

In addition to looking at the development history, interviews of the caregivers and the individuals are taken, and screening and diagnostic tools are used to make a diagnosis.

The article below lists tools and assessments that have been designed to help identify children and adults who have autism spectrum disorder. One should keep in mind that getting a positive score on these assessments and tools does not confirm a diagnosis of the disorder.

Instead, it is preferred to seek out a professional in the field who can validate the screening and provide appropriate guidance and support.

Screening for Autism Spectrum Disorder

The diagnostic process of autism spectrum disorder consists of many steps. Autism screening is done to identify the common signs of autism at an early age.

The screenings indicate that a child might pose a risk of having autism. The results of the screenings can further influence the decision of whether a formal is needed.

Early autism screening can help provide early intervention. Early intervention for autism is known to have long-term effectiveness and a positive impact on the prognosis of the autistic individual.

Developmental Monitoring

Developmental monitoring can be considered a process that encourages parents and caregivers to carefully monitor a child's growth. It is a continuous and proactive process in which a child’s skills and abilities are observed. Emphasis is laid on monitoring whether the child can meet the developmental milestones typical of their age.

If the child is not meeting the developmental milestones and exhibiting behaviour not typical of children in the same age group, it is advised to visit the doctor who can exercise developmental monitoring of their own.

The next would then lead to developmental screening.

Developmental Screening

According to the Centers for Disease Control and Prevention (CDC), a reliable diagnosis of autism is possible by a healthcare professional by the age of 2.

The American Academy of Pediatrics (AAP) advises that healthcare providers assess a child's development at 9, 18, and 30 months, during which autism screenings can be conducted as part of these evaluations.

Autism screening is a formal process which involves the use of autism checklists or assessment questionnaires which are completed by the healthcare professional as well as people who possess information about the autistic individual's daily life.

According to the Indian Academy of Pediatrics (IAP), for autism screening, children between the ages groups of 16 to 30 months should be screened with The Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-R/F) along with a clinical evaluation.

After the screening test that ensures that the child’s development in relationship to their skills and abilities is on track, it can indicate if further evaluation by a specialist is warranted.

If any concerns are raised after the screening, then a formal developmental diagnosis is recommended.

Developmental Diagnosis

The diagnosis of autism is made by a trained professional, such as a clinical psychologist, occupational therapist or developmental paediatrician.

The diagnosis will result in determining whether intervention services are needed for the child and what kind of intervention will suit the child the best. Along with this, the healthcare professional might suggest genetic counselling and testing.

During the formal evaluation, the specialist may observe the child, administer structured tests, ask questions to the parents or caregivers, or have them complete questionnaires. These assessments aim to identify the child's strengths and challenges and determine whether they meet the criteria for a developmental diagnosis.

In India, the DSM-5-TR criteria for autism spectrum disorder is used to base one's diagnosis. The criteria focus on two core characteristics—deficits in verbal and non-verbal communication and restricted and repetitive patterns of behaviour.

Standardised tools are used for assessment and to evaluate a child's patterns of behaviour, skills, and abilities. Several screening tools are used in India. Some of the most common ones in use are discussed below in this article.

Autism Screening Tools and Assessments

The tools for assessment can vary in terms of measures that rely on the report of parents or caregivers, measures that are based on direct observation of the individual, as well as other tests that assess development abilities like cognitive tests, evaluation of speech, sensorimotor evaluation, communication assessment, etc. 

The Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-R/F):

This checklist is a test that consists of 23 questions. It is used for children between the ages of 16 to 30 months. A positive score on this test leads to a follow interview which determines whether the child requires a referral. 

INCLEN-INDT (Indian Network for Developmental and Behavioral Pediatrics—Indian Diagnostic Tool for ASD:

Specially designed for use in India, this diagnostic tool assesses the social, behavioural and developmental skills of an individual. This helps in determining whether they meet the criteria for Autism Spectrum Disorder (ASD). 

Childhood Autism Screening Instrument:

This is a questionnaire which is answered by the parents or caregivers of the children. It is effective in identifying young children who are at risk of Autism Spectrum Disorder (ASD).

Social Communication Questionnaire (SCQ): 

This is another questionnaire consisting of 40 items that is completed by the parents and caregivers of children who are 4 years of age or older. 

Many more measures rely on parent/caregiver reports such as  

  • The Autism Behavior Checklist (ABC), Gilliam Autism 
  • Rating Scale, 3rd edition (GARS-3), and 
  • Autism Diagnostic Interview-Revised (ADI-R). 
Autism Spectrum Quotient (AQ) Test:

This test is suitable for people who are 16 years of age or older.  The questionnaire consists of 50 self-report items and it is suitable for teens and adults who have an IQ above 80. 

Autism Diagnostic Observation Schedule (ADOS):

The ADOS is used to evaluate the presence and severity of Autism Spectrum Disorder (ASD) in both children and adults. It provides a standardised way to identify common traits of autism by assessing an individual's behaviour and communication skills in various social scenarios. This tool helps caregivers and professionals pinpoint where a person falls on the autism spectrum and determine the most effective interventions and support they need.

Childhood Autism Rating Scale (CARS):

This is a 15-item questionnaire that is completed by a trained healthcare professional based on direct observation. The child’s growth is evaluated against the growth of a typical child of that particular age group. 

Indian Scale for Assessment of Autism (ISAA):

Consisting of 40 items, this assessment is comprehensive and developed specifically for the Indian population. There are both observational and interview-based questions in this assessment. The 40 items in ISAA are divided into six important domains: speech—language and communication, behavioural patterns, sensory aspects, cognitive aspect, emotional responsiveness, and social relationships and reciprocity. 

Aside from these aforementioned tools used for screening and diagnosis of autism, development and intelligence tests are also used for estimating verbal and non-verbal skills. They also use these types of tests to measure adaptive skills and evaluate if an individual also suffers from certain intellectual disabilities (that can co-occur with autism).

Once the signs of autism have been interpreted, it is advised to seek expert consultation from a paediatrician, psychiatrist, clinical psychologist, speech pathologist, or a speech, language and occupational therapist. 

The diagnosis of Autism Spectrum Disorder (ASD) is made by these experts only after going over the developmental history, clinical history, observed behaviour, scores received on tests of cognitive functioning, as well as other related symptoms. 


The screening and diagnosis of Autism Spectrum Disorder (ASD) is a complex process that involves multiple steps and the use of various standardised tools and assessments.

Early identification and intervention are crucial for maximising the potential and quality of life for individuals with ASD. Although there are no definitive medical tests for autism, healthcare professionals rely on developmental history, behavioural observations, caregiver interviews, and specific diagnostic tools to identify ASD.

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