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Diagnosis of Autism Spectrum Disorders

The signs and symptoms of Autism Spectrum Disorders become apparent in early childhood, and early detection of these conditions is essential so that treatments can begin as soon as possible. The earlier that treatments are started, the better are the chances that individuals with these conditions will be able to overcome some of their symptoms [ref].

Screening for Autism Spectrum Disorders

Screening is the process of identifying individuals - in this case children - who may have certain signs or symptoms suggesting that they could have an Autism Spectrum Disorder. Those children who have been identified by this screening process as potentially being at risk for the condition should then be sent for a thorough diagnostic assessment.

It is recommended that the screening process be done by pediatricians at children's regular check-ups between ages 9-30 months [ref]. It is also helpful for parents to be aware of certain early warning signs of Autism Spectrum Disorders and to report these to their pediatricians.

Even within the first year of life, the following signs and symptoms should alert clinicians or parents to the possibility that a child should be assessed for an Autism Spectrum Disorder, especially when several of them are present [ref]:

  • Being at an extreme of temperament and behavior, where the child is either highly irritable at most times, or tends to be alarmingly passive and oblivious to what's going on around them.
  • Poor eye contact with parents.
  • Poor response to parents' voices, especially to one's name being called, while being keenly aware of other environmental sounds.
  • Lack of recognition of parent's voice.
  • Poor attempts at interactive play with parents.
  • More interested in looking at objects than at people.
  • A delay in using pointing as a way to communicate, share, or draw someone's attention to something of interest.
  • A delay past age 9 months in starting to babble.
  • Little or no to-and-fro babbling with parent (usually begins around 6 months)
  • Lack of warm, joyful, reciprocating facial expressions
  • Lack of response to any kind of neutral statements ("oh no, it's raining!")

Later on in childhood, some of these other signs and symptoms should also serve as clues that a child could have an Autism Spectrum Disorder [ref]:

  • Doesn't seem to notice when the parent is in the room.
  • Acts as if they are in their own world. Prefers to play alone and seems to "tune others out."
  • Doesn't seem interested in playing with toys but likes to play with objects in the house.
  • Shows a strange attachment to hard objects (would rather carry around a flashlight or ballpoint pen than a stuffed animal or favorite blanket).
  • Can say the ABCs, numbers, or words to TV jingles but can't ask for things he/she wants.
  • Doesn't seem to have any fear.
  • Doesn't seem to feel pain.
  • Laughs for no clear reason.
  • Uses words or phrases that are inappropriate for the situation.
  • Doesn't try to look to see what someone else is pointing to.

The following signs and symptoms are considered "red flags," meaning that if any are present the child should be sent for an immediate evaluation for an Autism Spectrum Disorder [ref]:

  • No babbling by 12 months.
  • No pointing or other communicative gestures by 12 months.
  • No single words by 16 months.
  • No 2-word spontaneous (not parroted) phrases by 24 months.
  • Any loss of any previously acquired language or social skills at any age.

There are some screening tools that can be used to get a better sense if a child is at risk for an Autism Spectrum Disorder and if they should be sent for a diagnostic assessment. These screening tools are generally used for children who have already been identified as having some of the signs and symptoms described above, or who have a sibling with an Autism Spectrum Disorder:

The CSBS DPâ„¢ Infant-Toddler Checklist is completed by parents of children ages 6-24 months.

The Modified Checklist of Autism in Toddlers (M-CHAT) is completed by parents of children ages 16-30 months.

For more in-depth knowledge on proper screening practices for Autism Spectrum Disorder, pediatric health care professionals can refer to the following resources:

Diagnosing Autism Spectrum Disorders

The actual diagnosis of Autism Spectrum Disorders is based on a clinical assessment done by a psychiatrist, psychologist or pediatrician, and includes observations of the individual in question, and obtaining information from family members and teachers. The goal of this assessment is to determine whether the individual meets the diagnostic criteria for one of the principle Autism Spectrum Disorders, namely, Autism Disorder, Asperger's Disorder, or Atypical Autism.

There are various scales and structured assessment tools that are frequently used to aid clinicians in making a diagnosis of an Autism Spectrum Disorder and to determine the severity of an individual's symptoms. For a comprehensive listing and description of these instruments, see here. Some of the more commonly used instruments include:

The Autism Diagnostic Observation Schedule (ADOS) allows a trained interviewer to observe first-hand the various signs and behaviors characteristic of Autism Spectrum Disorders through the use of various short games and tasks that the interviewer performs with patients above age 2.

The Childhood Autism Rating Scale is an observational assessment tool used by a trained professional to identify children above age 2 with an Autism Spectrum Disorder and determine the severity of their condition. A score of 30-36 on 60 suggests a mild-to-moderate form of the disorder, whereas a score above 36 suggests moderate-to-severe Autism.

The Vineland Adaptive Behavior Scales are a set of semi-structured interviews designed to be given to the parents to assess their child's level of functioning in different areas of everyday life. There are national norms for these scales to which a given child's level can be compared.

The Aberrant Behavior Checklist is a scale that can be completed by any caregiver familiar with the patient, and assesses the extent of various kinds of problematic behaviors that the patient may have in association with his/her Autism Spectrum Disorder. This scale is valid for both children and adults, and is also useful for measuring change in these aberrant behaviors.

Medical tests for Autism Spectrum Disorders

There are no blood tests or imaging studies (such as CT scans or MRI scans) that can be used to make a diagnosis of an Autism Spectrum Disorder. However, medical tests are often important in order to determine whether an individual may have a general medical condition that could be contributing to their Autism Spectrum Disorder.

  • Language and hearing tests should be done for all individuals.
  • Genetic testing, metabolic testing, electroencephalogram (EEG) and MRI should be done for individuals who have mental retardation, neurological signs and symptoms, or who are suspected of having certain congenital syndromes like Fragile X.


Mental Retardation