Autism is a life-long neurodevelopmental condition, typically identified in early childhood, which interferes with the person’s ability to communicate and relate to others. Epidemiological data estimates the presence of 52 million cases of autism worldwide, affecting around 3% of children across the globe. The vast majority of autism research focuses on children with autism, a disproportionate number of interventions for autism are appropriate only for children, and most autism services available are geared primarily towards children. There has been a recent increase in interest regarding similarities and differences in the manifestations and the impact of the condition in different world regions. Despite this interest, however, evidence remains limited in low- and middle-income countries (LMICs), and it has been difficult to draw public and policy-maker attention to autism in particular and neurological and mental health conditions more generally in these countries.
- About 1 in 54 children has been identified with autism spectrum disorder (ASD)
- ASD is reported to occur in all racial, ethnic, and socioeconomic groups.
- ASD is more than 4 times more common among boys than among girls.
- Studies in Asia, Europe, and North America have identified individuals with ASD with an average prevalence of between 2% and 3%.
- About 1 in 6 (17%) children aged 3–17 years were diagnosed with a developmental disability
Symptoms must be present in early childhood but may not become fully manifest until social demands exceed capacities or may be masked by learned strategies in later life. Symptoms need to be functionally impairing and not better described by another DSM-5 diagnosis such as intellectual developmental disorder or global developmental delay. Currently, diagnosis of autism is based on observation of behavioral symptoms outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Because symptoms vary considerably from individual to individual, diagnosis can be quite challenging, and because it is a developmental disability, autism may affect an individual differently at different stages of their lifespan.
Epidemiological studies conducted over the last half-century suggest that the prevalence in ASDs is increasing around the world and that this increase is most likely due to improved awareness and reporting, expansion of diagnostic criteria, and enhancement of diagnostic tools. Additional explanations encompass changes in diagnostic practices, including expansion of developmental screening, increased diagnosis, and diagnostic substitution.
Common comorbidities associated with autism include physical symptoms such as insomnia, eating and digestive difficulties, along with intellectual disability and psychiatric symptoms of anxiety, inattention, irritability, and behaviour difficulties. One or a combination of these symptoms may significantly increase disability for the person affected.
Further priorities for research include the need for increasingly effective approaches to intervention at all life stages, empowerment of families supporting a person with autism, and training of nonspecialist health workers.
- Problems reciprocating social or emotional interaction, including abnormal social approach, difficulty establishing or maintaining back-and-forth conversations and interactions, inability to initiate or respond to an interaction, and problems with shared attention or sharing of emotions and interests with others.
- Severe problems in developing and maintaining relationships. This can range from difficulties with making friends and lack of interest in other people to difficulties in engaging in pretend play and age-appropriate social activities, and problems adjusting to different social expectations.
- Nonverbal communication problems such as abnormal eye contact, body language, posture, facial expressions, tone of voice and gestures, as well as an inability to understand these.
- Stereotyped or repetitive speech, motor movements or use of objects.
- Excessive, inflexible adherence to routines, ritualized patterns of verbal or nonverbal behavior, or insistence on sameness.
- Highly restricted, fixated interests that are abnormal in intensity or focus.
- Hyper- or hyporeactivity to sensory input or unusual interests in sensory aspects of the environment.