The prevalence of autism is currently one in 86 children. Typically it affects more boys than girls and knows no socio-economic or ethnic boundaries. Twin studies show a concordance of more than 80% in identical twins and a rate of 38% in fraternal twins, similar to that of normal siblings.
According to the Center of Disease Control’s (CDC) statistics for 2010 (published in 2014), the incidence of ASD in the United States is 1in 68, with five times more boys than girls being affected.
At present there is no laboratory test that can detect the presence of autism.
The diagnosis is essentially made through clinical observation by trained professionals, unlike most of the following co-existing disorders.
Autistic Spectrum disorder can co-exist with other well-known disorders such as:
- Congenital rubella syndrome: an infectious disease acquired from the mother during pregnancy
- Down Syndrome
- Neurofibromatosis: a condition in which there are tumours of the nervous tissue
- Tuberous sclerosis: an inherited disease of the nervous system and skin
- Fragile X syndrome: an abnormality of the X-chromosome that can cause mental deficiency
- Phenylketonuria (PKU): an inherited metabolic disorder
ASD can however, exist with any disorder. Common co-morbidity also includes:
- Anxiety Disorder
- Obsessive Compulsive Disorder
- Attention Deficit Disorder
- Childhood Disintegrative Disorder: where autistic symptoms develop after the age of three years
- Rett’s Disorder: presents primarily in girls. A blood test can detect this disorder. It is characterised by a deceleration in head growth and loss of purposeful hand skills and mobility. (Girls with this disorder almost always prefer people to objects.)
Checklist for early warning signs of ASD in young children
Early diagnosis and identification of a child at risk is of the utmost importance. To do this, the emotional and social coordination/regulation needs to be evaluated in a young child, along with regular developmental assessments done by a paediatrician. In a very young child the focus would be on being aware of behaviours that are NOT present.
Can the child answer social questions? Ask the child social questions such as “What is your name?” or “How old are you?” The response should not be reliant on verbal ability, but can include a show of fingers or a partial verbal response. If the child is unable to give a positive response to at least five of these questions, further investigation by a professional trained to diagnose ASD, such as a psychologist or psychiatrist, is necessary.
- Does the child respond consistently to the calling of his/her name? Call the child by name, without giving any instruction, while he/she is engaged in an activity. Do this twice during the consultation to determine consistency. A response would be indicated if the child looks towards the caller.
Note: A stranger and not a parent must do the calling to ensure that the response is to his/her name and not to the recognition of a familiar voice.
- Does the child show shared attention and read gestures? Point to an object across the room, and observe whether the child follows your gesture, e.g. point to a toy while saying, “Look at that [toy] on the bookshelf.” Ask the child to point to something other than an object he or she may find desirable, e.g. “Show me your nose”, or “Where’s the light?” The child should be able to do both.
- Does the child show expectation/anticipation during brief pauses in play? Play a peek-a-boo-type game with the child (e.g. hide your face, reappear unexpectedly and then repeat this action). The child should show facial signs of anticipation.
- Does the child reference the parent’s face for reassurance? Pick the child up during the consultation and observe his/her reaction. The child should look at the parent for help/reassurance.
- Does the child exhibit basic imitation skills? Say, “try this” and then perform a basic action, such as clapping your hands or putting your hands on your head. The child should attempt to copy your actions immediately.
Averted gaze, absence of a social smile, resistance to social engagement, sensory problems (which may be indicated by fussy eating, sensitivity to noise, arching of the body and difficulties with potty training), and language delays are further indications of an increased risk of ASD.
What is autism?
Symptoms of autism
Reviewed by Dr Louise Lindenberg, MBChB (Stell), MFHom (UK). Integrative Medical Practitioner specialising in Disorders onthe Autism Spectrum in children, Cape Town. February 2015.
Previously reviewed by Jenny Buckle, Reach Autism SA, (November 2010)