'Autism spectrum disorder' (ASD) is the term used by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 'Pervasive developmental disorder' (PDD) is the term used by the World Health Organisation International Classification of Diseases, 10th revision (ICD-10).
- Level 1 (requiring support)
- Level 2 (requiring substantial support), and
- Level 3 (requiring very substantial support).
In contrast to DSM-5, the ICD-10 classifies ASD as PDD and includes several subtypes, including childhood autism, atypical autism, and Asperger syndrome. The version of ICD-11 released in 2018 (anticipated for use in 2022) indicates that the ICD-11 classification of ASD will be similar to that in DSM-5.
- Recent estimates suggest a prevalence of 1-2%.
- ASD is three to four times more common in boys than girls.
- Around 50% of children with ASD have an intellectual disability.
- Genetic causes including gene defects and chromosomal anomalies is seen in 25% of cases.
- Family history: sibling recurrence risk of around 10% and concordance of 36-60% in monozygotic twins
- Advanced parental age: maternal age (≥ 40 years) and paternal age (≥ 50 years) reported to be independently associated with ASD risk in offspring
- Environmental factors (e.g., toxin exposure, prenatal infections) may increase the risk of ASD.
- Genetic diagnoses commonly associated with ASD include
- Tuberous sclerosis complex
- Fragile X syndrome
- Chromosome 15q11-13 duplication syndrome
- Angelman syndrome
- Rett's syndrome
- Down syndrome
The available evidence does not support the myth of association between immunisations and ASD.
- Genetic, perinatal, and environmental factors may alter brain development and result in a lifelong neurodevelopmental disorder.
- It may be a consequence of abnormal function in hippocampal/amygdala, in addition to other brain regions.
- Some authors suggest that some behavioral characteristics of ASD may be due in part to effects of
- Altered cytokine levels on neuronal cell proliferation, neuron death, and synaptic pruning→ altered microglia on phagocytosis of neurons
- Impaired social communication and interaction:
- Children frequently play alone and maybe relatively uninterested in being with other children.
- They may fail to regulate social interaction with nonverbal cues like eye gaze, facial expression, and gestures.
- Fail to form and maintain appropriate relationships and become socially isolated.
- Repetitive behaviours, interests, and activities:
- Stereotyped and repetitive motor mannerisms, inflexible adherence to nonfunctional routines or rituals are often seen.
- Children are noted to have particular ways of going about everyday activities.
- ASD is often associated with intellectual impairment or language impairment.
- Attention deficit hyperactivity disorder (35%) and epilepsy (18%) are also commonly seen in children with ASD.
- ASD is also associated with a higher head circumference to the brain volume ratio.
Indications for specialist referral for further assessment (NICE, 2011):
- Refer children younger than 3 years if there is a regression in language or social skills.
- Consider referring children and young people if you are concerned about possible ASD based on reported or observed signs and/or symptoms.
- Factors associated with an increased prevalence of ASD.
- The likelihood of an alternative diagnosis.
The DSM-5 diagnosis of ASD is characterized by:
- Persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following, currently or by history:
- Deficits in social-emotional reciprocity including verbal interaction or sharing interests
- Deficits in non-verbal communicative behaviours used for social interaction.
- Deficits in developing and understanding relationships.
- Restricted, repetitive patterns of behaviour, interests, or activities, as manifested by at least 2 of the following, currently or by history:
- Stereotyped or repetitive motor movements, use of objects or speech
- Insistence on sameness, inflexible adherence to routines, or ritualised patterns of verbal or non-verbal behaviour
- Highly restricted, fixated interests that are abnormal in intensity or focus
- Hyper- or hypo-reactivity to sensory input
- Unusual interest in sensory aspects of the environment
- Symptoms must be present in the early developmental period
- Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.
- These disturbances are not better explained by intellectual disability (intellectual development disorder) or global developmental delay. Intellectual disability and ASD frequently co-occur; to make comorbid diagnoses of ASD and intellectual disability, social communication should be below that expected for the general developmental level.
ICD-10 criteria for the diagnosis of pervasive developmental disorders is also based on atypical social communication and interaction and restricted, repetitive patterns of behaviour, activities, and interests.
- Typical: a pervasive developmental disorder defined by the presence of abnormal and/or impaired development that is manifest before the age of 3 years, and by the characteristic type of abnormal functioning in all 3 areas of psychopathology: reciprocal social interaction, communication, and restricted, repetitive behaviour.
- Atypical: A pervasive developmental disorder that differs from autism in terms either of age of onset or of failure to fulfil all 3 sets of diagnostic criteria. More common in people with severe learning disabilities and those with a severe specific developmental disorder of receptive language.
Attention deficit hyperactivity disorder:
- Similarities: social communication difficulties.
- Differences: normal pragmatic language skills, nonverbal social behaviour, and imaginative play. Lack of restricted, repetitive patterns of behaviour, interests, and activities.
Social (pragmatic) communication disorder:
- Similarities: impairment in social communication and social interactions.
- Differences: absence of restricted, repetitive patterns of behaviour, interests, or activities.
Global developmental delay/intellectual disability:
- Similarities: language delay, may show repetitive behaviours.
- Differences: social responsiveness and communication appropriate for the developmental level.
Developmental language disorder:
- Similarities: social communication difficulties.
- Differences: normal reciprocal social interactions, and normal desire and intent to communicate. Appropriate imaginative play.
The goal is to increase functional independence and quality of life through
- Learning and development, improved social skills, and improved communication
- Decreased disability and comorbidity
- Aid to families
Non Pharmacological Therapy:
- Early educational and behavioural interventions:
- Applied behavioural analysis (ABA).
- ASD preschool program.
- Treatment and Education of Autistic and Communication related handicapped CHildren (TEACCH)/Structured Teaching method.
- Early Start Denver Model (ESDM).
- Joint Attention Symbolic Play Engagement and Regulation (JASPER).
- Pharmacologic interventions: no consistent evidence demonstrating medication-mediated improvements in social communication
- SSRIs: helpful to reduce symptoms like repetitive stereotyped behaviour, anxiety, and aggression
- Antipsychotic drugs: useful to reduce symptoms like aggression, self-injury.
- Methylphenidate: for attention deficit hyperactivity disorder (ADHD).
- Family support and counselling:
- Parental education on interaction with the child and acceptance of his/her behaviour.