Diagnosis of Autism Spectrum Disorder

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Early diagnosis and intervention are key factors associated with a better prognosis. In the majority of Western countries, the average age of diagnosis of ASD is above four years, although it can be diagnosed before the age of two. 

There are currently no medical tests available for the diagnosis of autism. Specially trained doctors and psychologists therefore identify autism based on specific behaviours.

Parents are usually the first to realise their child has some strange habits, such as almost never looking into their eyes (eye contact avoidance), not responding to their name or playing with toys in a repetitive or unusual manner. 

Both the detection of some strange behaviours in a child and a comparison of the skills they have acquired with respect to their siblings or other children around them can represent warning signs. So the child may be quieter or more passive than others, utter very few words, perhaps they do not babble or use gestures to communicate, do not respond to their name or hardly ever smile or express pleasure when their parents try to share activities with them. 

The presence of a warning sign does not necessarily mean the child has a developmental problem. However, it does indicate the need for a more thorough assessment. It is therefore important to discuss any concerns with a paediatrician so they may perform the necessary tests to identify the causes of any warning signs; these causes could include hearing problems or delays in language development, amongst others. 

The main objective is to confirm or rule out the presence of a problem and obtain an accurate diagnosis as early as possible in order to plan the most suitable intervention for each child and their family. 

Upon identifying the risk of a communication and social development problem, the paediatrician will refer the family to a specialist for a more comprehensive assessment. Each catchment area has their own specialised care centres where a multidisciplinary medical team will evaluate different aspects of the child’s condition.

Tests of Autism Spectrum Disorder

Notepad with a symptoms questionnaire

Questionnaires. Questionnaires adapted to different developmental ages are available to help identify any warning signs.

Family: father, mother and daughter

Observation of behaviour and psychological assessment. Diagnosis is based on observations of the individual’s behaviour and includes a psychological assessment of their language, communication and social skills as well as their cognitive development. This is done using specific diagnostic procedures, such as questionnaires, interviews, tests designed to observe the individual's behaviour and other area-specific tests. 

Blood collection tube

Complementary tests. The medical team may also request some complimentary diagnostic tests, e.g., blood analyses, neuroimaging tests, audiograms or auditory brainstem response tests, which are used to rule out certain metabolic or neurological disorders, or hearing impairments. However, these tests alone can never provide a definitive diagnosis.

DNA molecule or helix

Research into personal and family medical background and genetic study. These provide very valuable information for the diagnosis.

Occasionally, ASD is diagnosed later on and suspicions are aroused because of persistent social and emotional problems or even due to learning difficulties. As with small children, the diagnosis in adolescents and adults involves personal observation and an interview by a trained specialist. At this stage in life, the diagnosis usually provides relief and understanding for those who have, for a long time, been struggling with their difficulties to form social relationships. In addition, diagnosis can help gain access to support therapies and technologies that enhance function in other problem areas and therefore improve the individual’s overall quality of life.

Substantiated information by:

Antonia Bretones Rodríguez
Rosa Calvo Escalona

Published: 20 February 2018
Updated: 20 February 2018

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