Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by social interaction and communication difficulties, alongside restrictive and repetitive behaviors and interests. The term “spectrum” reflects the wide range of presentations, from severe disability to cognitive strengths. Historically, terms like Asperger syndrome were used to describe individuals with higher functioning or higher IQ, but these are now considered part of ASD, as are other neurodevelopmental conditions like childhood disintegrative disorder. ASD is increasingly seen as an example of neurological and cognitive variation among people.
Core Domains of ASD
The clinical presentation of ASD varies greatly, but the two core domains affected are:
- Social Communication and Interaction: Symptoms can include delayed nodding or shaking of the head, lack of vocalization or babbling, delayed language development, fewer facial expressions, and not pointing at objects of interest. These may be due to “mind blindness” or a lack of theory of mind, where individuals with ASD struggle to imagine what others are thinking.
- Repetitive and Restricted Behavior: This includes repetitive movements like flapping, distress with changes in environment, extreme reactions to sensory inputs, not playing games like peekaboo, and not engaging with other children. Regression of language before the age of three is a red flag for possible ASD, while regression after this age warrants investigation for other causes.
Manifestations in Different Age Groups
Children: Symptoms often appear before 24 months and can include delayed speech, fewer facial expressions, and repetitive behaviors. They may also show an inability to play interactively with others and may not point at objects of interest.
Older Children and Adolescents: These individuals may struggle with making their feelings known, often expressing frustration through emotional outbursts. They might have restricted and ritualistic approaches to eating and drinking and face difficulties forming friendships.
Adults: ASD should be considered if there are difficulties with social communication or interaction, stereotyped restricted behavior, resistance to change, or restricted interests that began in childhood. Adults often present during times of stress, with issues in finding and keeping employment, previous contact with mental health services, and difficulties in sustaining social relationships.
Cognitive and Intellectual Profiles
Many individuals with ASD have an uneven cognitive profile, with strengths and weaknesses in different cognitive tasks. About 40 to 80 percent of people with ASD have an intellectual disability, and 20 to 30 percent may also have epilepsy.
Pathophysiology and Risk Factors
The exact pathophysiology of ASD is not known, but it is believed to result from a combination of genetic and environmental factors. Genetic influence accounts for 50 to 80 percent of the variation in ASD, with higher heritability rates observed in monozygotic twins. Environmental risk factors include prenatal exposure to sodium valproate, increased parental ages, and prematurity. Although vaccines were once thought to cause ASD, current evidence refutes this claim.
Diagnosis
ASD diagnosis is typically made by a specialist based on clinical history and examination. Standardized tools such as the Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview-Revised (ADI-R) may be used. The DSM-5 criteria for ASD require persistent deficits in social communication and interaction across multiple contexts, restricted repetitive patterns of behavior, interests, or activities, and these symptoms must be present in the early developmental period, cause significant impairment, and cannot be better explained by intellectual disability or global developmental delay.
Management and Treatment
The goal of treatment and management is to maximize the individual’s function and quality of life while supporting their families or caregivers. Management is generally multidisciplinary and often includes parents or caregivers. Approaches can vary greatly between individuals and over time.
Applied Behavioral Analysis (ABA): This involves analyzing behavior and matching it with appropriate strategies, tailored to the individual. Skills are taught through small, progressive changes over time, including cognition, communication, self-care, and employment support.
Speech and Language Therapy: This therapy uses a range of communication methods, including speech, pictures, and speech-generating devices.
Physiotherapy and Occupational Therapy: Useful for those with deficits in motor function planning or sensory processing.
Pharmacological Therapy: Not typically used for core features of ASD, but antipsychotics like risperidone or aripiprazole may be used when behavioral techniques are ineffective. Associated disorders like depression, anxiety, OCD, and insomnia may benefit from pharmacotherapy, usually alongside cognitive behavioral therapy.
Dietary Modification: Generally, dietary changes have not shown significant benefits in managing ASD symptoms.