Children identified to be at risk should be referred for comprehensive developmental and diagnostic assessment for autism spectrum disorders. This assessment might be done through community resources (eg, early intervention staff, educators, psychologists, or speech pathologists), educational agencies, or local developmental clinicians. Reviews of early identification and screening are available.15,17,19
If concerns that a child has autism spectrum disorder are validated, comprehensive diagnostic assessment is needed (). These assessments should be multidisciplinary, addressing core symptoms, cognition, language, and adaptive, sensory, and motor skills. The multidisciplinary team should include clinicians skilled in speech and language therapy, occupational therapy, education, psychology, and social work. Ozonoff and colleagues19
reviewed domains of assessment, including neuropsychological, attention, executive function, and academic functioning.
Stages of identification and diagnosis of autism spectrum disorder
Diagnostic assessment of autism spectrum disorders includes use of ICD or DSM diagnostic criteria,21
and standardised methods to assess core (panel 1
) and comorbid symptoms (). This multidisciplinary assessment includes a review of caregiver concerns, descriptions of behaviour, medical history, and questionnaires.21
Input from families about their observations and concerns are crucial. Although parents are often aware of developmental problems in their child from age 18 months, a diagnosis is often not made until 2 years after the initial expression of parental concern. In some cases diagnosis has not been confirmed until close to age 6 years,28
which is sometimes associated with delays attributable to access to services and regional variations in diagnosis.
Comorbid symptoms or disorders
shows methods for diagnosis and categorisation of autism spectrum disorders.19
Standardised questionnaires such as the social responsiveness scale provide data about severity of core deficits of socialisation, and the revised repetitive behaviour scale provides information about stereotyped or repetitive behaviours (). Use of two research quality, gold-standard assessment methods based on DSM criteria, the autism diagnostic observation schedule (ADOS)58
and the revised autism diagnostic interview (ADI-R),59
have improved accuracy and reliability of diagnosis.19
The ADOS is a semistructured standardised assessment for social behaviour, communication, and imaginative play, and is used in research and clinical settings. To diagnose individuals with intellectual disability is difficult because behaviours might not be specific to autism spectrum disorders; the ADOS diagnostic algorithm was revised to address these issues. The time needed for administration of the ADI-R (1–3 h) precludes its use in many clinical settings.
Selected methods for autism diagnosis and categorisation
Comorbid disorders are common in children60
and families of children with autism spectrum disorders, and might have a greater effect on function and outcome than do core symptoms (). Parents of affected children have increased rates of stress and mental health comorbidity (eg, anxiety and depression), which might be associated with their child’s behavioural problems.61
Comorbid behavioural or developmental disorders include intellectual delays, inattention or other symptoms of attention deficit-hyperactivity disorder, externalising behaviours (such as aggression and disruption), affective difficulties (such as depression or anxiety), sleep disruption, and sensory differences.22
Medical comorbidities, such as gastrooesophageal reflux, food selectivity, and neurological disorders (eg, tics and seizures) also have a substantial effect on management and on the family. Some behavioural or affective comorbidities might be targets for pharmacotherapy.
A comprehensive diagnostic assessment should include medical investigation for causes and associated diagnoses.62
Results will inform families about related genetic, neurological, or medical problems, and risk of recurrence in future siblings. An appropriate medical investigation for causes includes a detailed history and physical examination (with careful examination for dysmorphology). Clinical genetic assessment might include laboratory studies ordered by the primary care practitioner or referral to a clinical geneticist. Genetic laboratory studies can include routine karyotype and molecular DNA testing for fragile X, or comparative genomic hybridisation, or both.63
Associated medical problems such as seizures show a need for electroencephalogram (EEG), substantial regression a need for metabolic investigation, and abnormal head size a need for neuroimaging in some. Routine brain imaging or EEG is not recommended unless specific clinical features are indicative of an active neurological process needing clinical diagnosis.