Diagnosis of Autism Spectrum Disorder

Diagnosis of Autism spectrum Disorder (ASD) requires a differential determination as to whether the child is on the spectrum or whether the observed behaviours are the result of a medical or other condition. In the clinic, we use a structured procedure as described below. Often families are referred to us after a diagnosis has been made by another health professionals. In which case we will use the information already gathered by these professionals and conduct other tests if necessary. Autism Spectrum Disorder is not diagnosed using empirical biological tests, such as a blood test or brain scans. A diagnosis of autism is made by an expert Psychologist after gathering and considering the following information:

  • A developmental and clinical history to help differentiate ASD from other disorders
  • The Childhood Autism Raring Scale (CARS)
  • The Autism Diagnostic Interview (ADI-R) (administered to parents for history and current behavioural functioning)
  • Autism Diagnostic Observation Schedule (ADOS): Observations of behaviours through a structured assessment of the child in a play-like setting.
  • Testing of cognitive functioning WPPSI-III or WISC-V (not required for ASD Dignosis, but required by Education Department and other funding sources DHSS, NDIS etc.
  • Receptive and expressive language assessment. to differentiate between Pragmatic language disorder and
  • A VINELAND 3, adaptive behaviours scale to determine the child's day to day deficits in functioning, dressing, eating etc.

Developmental and clinical history

The Autism Diagnostic Interview-Revised (ADI-R)

ADIR The Autism Diagnostic Interview-Revised (ADI-R) is a structured interview conducted by a Psychologist with the parents of individuals who have been referred for the evaluation of possible autism or autism spectrum disorders. The interview, used by researchers and clinicians for decades, can be used for diagnostic purposes for anyone with a mental age of at least 18 months and measures behaviour in the areas of reciprocal social interaction, communication and language, and patterns of behavior.

The interview covers the referred individual’s full developmental history, is usually conducted in the clinic by a trained Psychologist, and generally takes one to two hours. The caregivers are asked 93 questions, spanning the three main behavioral areas, about either the individual’s current behaviours.

The interview is divided into five sections: opening questions, communication questions, social development and play questions, repetitive and restricted behaviour questions, and questions about general behavioural issues. Because the ADI-R is an investigator-based interview, the questions are very open-ended and the investigator is able to obtain all of the information required to determine a valid rating for each behaviour. For this reason, parents and caretakers usually feel very comfortable when taking part in this interview because what they have to say about their children is valued by the interviewer. Also, taking part in this interview helps parents obtain a better understanding of Autism Spectrum Disorder and the factors that lead to a diagnosis.


Our ability to learn depends on our cognitive skills. A psychologist at the clinic can assess your child's cognitive abilities. It is essential that the psychologist be experienced with Autism Spectrum Disorders, so he/she can make appropriate interpretations of your child's behaviours. The psychological assessment will provide valuable information for the formulation of your child's treatment program and management strategies.

Receptive and expressive language

A number of tests are used to form a picture of your child's expressive and receptive communication skills. Both, verbal (spoken) and non-verbal communication (use of gesture and reading of body language) skills will be tested. Many children will also have their pragmatic language skills assessed. Pragmatic language skills refer to how effectively children use words and gesture to communicate with others. Evaluation of the child's communication skills should include a comprehensive assessment of the oral motor and speech motor systems. This may include:

  • Non-speech motor functions posture and gait, gross and fine movement coordination; oral movement coordination, mouth posture, drooling, swallowing, chewing, oral structures, symmetry, volitional vs. spontaneous movement
  • Speech motor functions: struggle and strain during speech attempts, visible groping of mouth, deviations in prosody (rate, volume, intonation, etc.), fluency of speech, hyper/hyponasality, speech diodochokinesis involving alternative and sequential speed on consecutive repetitive attempts at utterance, volitional vs. spontaneous attempts.
  • Articulation and phonological performance: amount of verbal output, sound repertoire, reluctance to speak, interactive ability, intelligibility and type of errors, effects of performance load and increasing complexity; connected speech sampling.
  • Language performance: comprehension and expression, type of utterances, semantic and syntactic ability, effect of increased length of input, conversational abilities.
  • Others: ability to sustain and shift attention, reaction to speech, distractibility.


Childhood Autism Rating Scale 2Childhood Autism Rating Scale (CARS).

Information is obtained about the child's behaviour using standardised rating scales such as the Childhood Autism Rating Scale (CARS). The CARS is a15-item behaviour rating scale which helps to identify children with autism and to distinguish them from developmentally handicapped children who do not have autism. In addition, it distinguishes mild or moderate from severe autism.

Developed over a 15-year period and with more than 1,500 cases, the CARS includes items drawn from five prominent systems for diagnosing autism. Each item covers a particular characteristic, ability, or behaviour. After observing the child and examining relevant information from parent reports and other records, A senior Psychologist at the Clinic rates the child on each item. Using a 7-point scale, he or she indicates the degree to which the child¹s behaviours deviate from those of a normal child of the same age.

Autism Diagnostic Observation Schedule

ADOS-2 The ADOS can be used to evaluate almost anyone suspected of having autism: from toddlers to adults, from children with no speech to adults who are verbally fluent. This semi-structured assessment consists of various activities that allow a specially trained Psychologist to observe social and communication behaviours related to the diagnosis of pervasive developmental disorders. These activities provide interesting, standard contexts in which interaction can occur.
The ADOS consists of four modules, each requiring 35 to 40 minutes to administer. The individual being evaluated is given just one module, depending on his or her expressive language level and chronological age. Following guidance provided in the manual, you select the appropriate module for your client.

Module 1 is used with children who do not consistently use phrase speech, Module 2 with those who use phrase speech but are not verbally fluent, Module 3 with fluent children, and Module 4 with fluent adolescents and adults. The one group within the autism spectrum that the ADOS does not address is nonverbal adolescents and adults.

Cut-off scores are provided to determine a broader diagnosis of PDD / atypical autism / or autism spectrum, as well as the traditional, narrower conceptualisation of autism.

Offering standardised materials and ratings, the ADOS gives you a measure of autism spectrum disorder that is unaffected by language. Because it can be used with a wide range of children and adults, it is a cost-effective addition to any hospital, clinic, or school that serves individuals with developmental disorders.


Medical and psychiatric conditions that may result in Autistic-like behaviours need to be excluded. For example PANDAS, Rett's Disorder or Childhood Disintegrative Disorder to name a few. The following is a brief description of the other pervasive developmental disorders

  • Pervasive Developmental Disorder, Not Otherwise Specified (PDD,NOS) is diagnosed when autistic symptoms are present but the full criteria for autistic disorder are not met. Therefore, persons diagnosed with PDD-NOS present with autistic symptoms, but typically are not as involved with the social and communication deficits as persons who meet the full criteria for autism. Generally, they are higher functioning and more responsive to treatment.
  • Rett's Disorder is a degenerative disorder which affects only girls and usually develops between the ages of six months to 18 months. Some of the characteristic behaviors may include the following: loss of speech, repetitive hand-wringing, body rocking, head banging and social withdrawal. Individuals suffering from this disorder may be severely to profoundly mentally retarded. This disorder, along with childhood disintegrative disorder, is extremely rare.
  • Childhood Disintegrative Disorder (CDD) is included among the PDDs because these children apparently develop normally for two or more years before suffering a distinct regression in their abilities. Affected children lose previously acquired functional skills in expressive or receptive language, social skills or adaptive behavior including bowel or bladder control, play, or motor skills. CDD occurs much less frequently than autism or one of the other PDDs. Children with CDD exhibit the social, communicative and behavioral deficits observed in autism, including the loss of desire for social contact, diminished eye contact, and loss of non-verbal communication.
  • Global Developmental Delay


Information is gathered with regards to whether there are any genetic anomalies that may account for some of the observed behaviours. This is done through a Paediatrician, either the child's own or a specialist on our recommendation. We also carry out a screening of Genetic Polymorphisms to look for gene variations that can contribute to cellular malfunctions.


It is important to ensure that the child is able to hear normally. One of the behaviours noticed by many parents is their child's unusual auditory response of "acting as though deaf". An auditory assessment will exclude the possibility of a hearing impairment. If necessary a hearing test may be arranged by the clinic.