Clinical syndromesAutism spectrum disorders
Section snippets
Prevalence
The primary impairment in social relatedness and reciprocity was once considered a particular characteristic of rare individuals in the population, but is now understood as a broad dimension of individual difference that is widely distributed in the general population.1 Historically the prevalence of childhood autism was thought to be 4–5 per 10,000 births; however, a number of recent studies have found prevalence rates of 20–40 per 10,000.2 For the broader autism spectrum, the prevalence may
Associated disorders
Medical conditions of possible aetiological significance have been reported in 6–30% of autistic individuals. Values are lower in population-based samples than in clinically accrued samples, and lower in high-functioning individuals than in developmentally delayed ones. The risk of ASD is increased in tuberous sclerosis and in some genetic anomalies such as fragile X syndrome and Turner syndrome. Tuberous sclerosis may provide an important clue to brain pathology, as lesions in the temporal
Aetiology
Autism is a strongly heritable disorder. This genetic predisposition is polygenic in character, with two to five – and possibly as many as ten – genes responsible. None has yet been identified, although considerable international collaborative efforts have indicated that susceptibility genes may be located on chromosomes 2, 7, 16, and 17.4 It is entirely plausible that the autism phenotype might result from a number of genetic components and mechanisms, and recent evidence has emerged that
Diagnosis
Until recently, many children with ASD were not diagnosed until 4 or 5 years of age, or even later. However, progress has been made in the earlier identification of ASD, and many children are now first identified in the pre-school period.8 In any clinical service that assesses developmental problems in pre-school children, ASD is an important part of the differential diagnosis from the more common problems of speech and language delay, general developmental delay, and behavioural difficulties.
Differential diagnosis
The differential diagnosis of autism includes hearing problems, global developmental delay, and language delay or disorder, especially receptive language delay. In very young or profoundly delayed children, differentiating autism plus developmental delay from developmental delay alone may be difficult. However, social interest, use of pointing and other non-verbal gestures, imitation and pretend play skills would usually be commensurate with overall developmental level in a child with general
Assessment and investigations
A multidisciplinary approach to assessment is required. The composition of teams varies, but commonly includes a paediatrician, a child psychiatrist, a speech and language therapist, a clinical psychologist, and an occupational therapist or physiotherapist.
The information necessary for diagnosis includes a detailed developmental history, parents’ descriptions of the everyday behaviour of the child, and direct assessment of the child’s social interaction style and communicative and intellectual
Management and intervention
Educational provision should maximize the child’s social and communicative abilities, as well as their intellectual functioning and academic attainments. There is increasing evidence that appropriately targeted intervention improves outcome in children with ASD. There is some evidence of the benefits of intensive early behavioural intervention, although many professionals would advocate programmes that also target the core deficits in social relating and communication.12 In addition, there is
Medication
Current pharmacological treatments do not treat the core features of ASD. Neuroleptics such as trifluoperazine and haloperidol have been used to manage stereotyped (including self-injurious) behaviours and hyperactivity, but can produce dystonic reactions and drowsiness. Such behavioural problems are usually found in individuals with severe developmental delay. Some recent reports suggest that irritability, anxiety, aggression, and repetitive behaviours may be ameliorated by the serotonin
Course and prognosis
The course and outcome of ASD are dependent largely on language and IQ, and vary considerably. There is often improvement after the pre-school years, especially in the acquisition of language skills. However, for the majority of individuals, significant social impairment is lifelong. An IQ above 70 and onset of functional language by 5 years of age are good prognostic signs. Asperger syndrome is associated with a better prognosis because of relatively good IQ and language skills, but few
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