Autism spectrum disorder (ASD) is a term used to define a complex array of neurodevelopmental disorders characterized by social communication deficits and restricted and repetitive behaviours.
Signs and Symptoms
ASD signs and symptoms are evident as early as twelve months and the diagnosis can reliably be made by experts by two years old. Early symptoms of ASD include inconsistent or lack of response to name, poor eye contact and impaired joint attention. Research in Molecular Autism has confirmed that infant neurocognitive ASD markers relate to the disease in mid-childhood, having implications for understanding the neurodevelopmental mechanisms that lead from risk to disorder and for identification of potential targets of pre-emptive intervention.
Social and language deficits
Children with ASD demonstrate significant social deficits and have limited imaginary play, less interest in other children, and significant difficulty with reciprocal play as they get older. Language deficits include delays in achieving phrase speech, or later, engaging in reciprocal conversation.
Repetitive and unusual behaviours
Repetitive behaviours are also criteria for diagnosing autism. Children with ASD may rigidly adhere to routines, have difficulty transitioning between activities or environments, and engage in repetitive movements like hand-flapping, toe-walking, or rocking.
ASD is primarily a genetic disorder; more than 100 genes that cause ASD have been identified to date and perhaps 1000 more are implicated based on large scale genetic studies, regularly showing overlap with other psychiatric diseases. Research published in Molecular Autism demonstrates that common genetic variations exert substantial additive genetic effects on ASD occurrence.
While the prevalence of ASD is increasing, the diagnostic criteria have also been changing and it is still not entirely clear exactly how common ASD is. The centre for Disease Control (CDC) does monitoring studies and the latest numbers suggest that 1 in every 68 children is affected. However, studies that use gold standard diagnostic procedures and observe children directly find rates closer to 1 in 150. ASD is prevalent in all different populations and across racial, ethnic, and socioeconomic lines. Yet boys are four to five times more likely to be affected than girls. Research in Molecular Autism investigated potential sex specific factors which may influence the high prevalence in males.
The American Academy of Paediatrics recommends that all children should be screened for ASD at 18 and 24 months using a specific screening tool like the Modified Checklist for Autism in Toddlers. If there are red flags, the next step is a gold-standard evaluation for ASD, which consists of direct observation of the child (e.g. using the Autism Diagnostic Observation Schedule) and an in-depth parent interview done by specialists. For all children suspected of having ASD, genetic testing is also now recommended. The current standard of evaluation is to use chromosomal microarray testing but soon even higher resolution genetic testing (e.g. whole exome sequencing) will be routine.
Treatment usually includes speech therapy, occupational therapy, physical therapy, and behavioural therapy. The most commonly prescribed behavioural therapy in ASD, and the one with the most evidence to support its use, is applied behavioural analysis (ABA). ABA teaches children skills using positive reinforcement. It is now well accepted that the earlier and more intensively you intervene, the more robust the gains. Medications can also be used to target associated symptoms commonly seen in children and adults with ASD, like anxiety, attention deficit, hyperactivity, irritability, and aggression.