Original articlePreschool children with autism spectrum disorders in Taiwan: follow-up of cognitive assessment to early school age
Introduction
Autism is a developmental behavioral syndrome defined by the presence of communication and social deficits; ritualistic, repetitive behaviors; and onset prior to age 3 years [1]. As Gillberg and colleagues’ follow-up study of children under age 3 has demonstrated, clinical diagnosis of autism can be made long before the pre-school years [2]. Lord's follow-up study on very young children also showed that reliable diagnosis of autism in 2-year-old children is possible, but that criteria must be modified from standard diagnostic formulations in order to take into account both the particulars of how autism is manifested in very young children and the likelihood of overlap with children with other severe communication disorders and cognitive delays [3], [4].
Cognitive abilities and level of communication of children around school age are said to be the two most important variables predicting outcome of autism [5]. The absence of communicative speech at 6 years of age and an intelligence quotient (IQ) below 50 around school age predict severe restriction of social and adaptive functioning in adult life. Because various studies have demonstrated that the assessment of cognitive ability is stable throughout childhood and adolescence in autism spectrum disorders [6], [7], cognitive assessment of autistic subjects has become an essential part in developing comprehensive treatment plans.
The intellectual assessment of preschool autistic children, especially those who are very young (3 years and younger), those with no language or very limited communication skills, and those with severe delays in other areas is not a straightforward process. The lack of social and communication related ‘test-taking skills’ rendered evaluation of these children particularly difficult. In the Taiwanese context, psychometric tools for assessing preschoolers’ intelligence level were mainly adapted from the West and have only recently been standardized. As a result of the above limitations, routine practice for the preschool populations in Taiwanese developmental clinics was to apply the results of the parental report Chinese Child Developmental Inventory (adapted from the Minnesota Child Development Inventory) in assessment, rather than using individualized and standardized cognitive tests administered by psychologists [8].
Nevertheless, as several Western studies have demonstrated, the performance of autistic children on intelligence tests is as stable and predictable from later preschool years to school age as that of non-autistic children with communication handicaps and/or behavior disorders [9], [10]. The purpose of our study was to investigate whether the above statement can be applied in the Taiwanese context. This study compared the results of developmental/intelligence tests across an average of 22 months in a group of preschool-age autistic subjects with a matched group of non-autistic preschoolers followed up in the developmental clinic of Kaohsiung Medical University. The objectives of the study were to: (1) explore the demographic characteristics in a cohort of 6–7-year-old children with autism spectrum disorders; and (2) determine whether the cognitive assessments for Taiwanese preschool autistic children would manifest stability, as demonstrated in Western reports.
Section snippets
Methods
From the data gathered at the developmental clinic of Kaohsiusng Medical University, we retrospectively reviewed the data of children born between January 1995 and August 1996 for analysis. The age range of this cohort was chosen so that children entering elementary school (grade I or II) as of September 1, 2002 were selected for analysis. The total number of children reviewed was 577.
All the children were subjected to nearly identical procedures when they were evaluated at the clinic. All
Results
In the cognitive follow-up study, the case group comprised 16 autistic children (13 males, three females) with an average age at initial assessment of 3 years 8 months. The control group comprised 16 non-autistic children (12 males, four females) with an average age at initial assessment of 3 years 11 months. The final diagnosis for the control group when they turned 6 years old was four children with mental retardation and 12 children with isolated developmental language disorder. The average
Discussion
Patterns of intellectual deficits in children with autism spectrum disorders are reported to be changing over the past few decades. Because of the broadening of the conceptualization of autism spectrum disorder, better ascertainment, and the expanded number of mildly affected children, the rate of autism associated mental retardation is decreasing from earlier reports of 75% [16], to much lower figures of 40% and 55% in large epidemiological series [17]; a recent UK study reported only 26% of
Acknowledgements
This study was supported by Grant for Children with Developmental Delay from the Department of Health, Taiwan, ROC.
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