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Developmental Trajectories of Behavioural Symptoms in ASC
Objectives: The aims of this study were twofold. First the study aimed to map developmental trajectories of social impairments, repetitive behaviours and sensory behaviours in children with ASC. Second, the study aimed to explore developmental interrelationships between the three areas of impairments.
Methods: The parents of thirty-six children with ASC aged between 6 and 16 years of age completed the Repetitive Behaviour Questionnaire-2 (RBQ-2; Leekam et al, 2007), the Social Responsiveness Scale (SRS; Constantino and Gruber, 2005) and the Short Sensory Profile. Autism severity was measured by the Childhood Autism Rating Scale, Second Edition (CARS 2; Schopler et al, 2010) in 27 of the children and, for 8 children, it was measured with the Autism Quotient (Auyeung, Baron-Cohen, Wheelwright & Allison, 2008). The protocol for the study received ethical approval from the University of Portsmouth Ethics Committee which follows the guidelines of the British Psychological Society.
Results: The results showed differential trajectories for each area of behaviour relative to chronological age. Social difficulties remained relatively stable across the age range. In contrast developmental changes were observed in sensory behaviours, repetitive behaviours relating to Insistence of Sameness and repetitive sensory-motor behaviours. In terms of developmental interrelationships, while the development of social and sensory impairments seem closely linked, the development of repetitive behaviours seems to be relatively independent to the development of impairments in the two other domains.
Conclusions: The results demonstrate that while some behavioural symptoms change over the life span others remain stable. These findings have important implications for our conceptualisation of ASC. First, the results raise the possibility that while social impairments have a strong genetic component and are therefore impervious to environmental influences, the development of impairments in the two other areas may be successfully influenced by interventions. Second, the possibility that some areas of impairment in autism, in particular Insistence of Sameness, may be a ‘side-effect’ of genetic difficulties in other areas and note core to ASC will also be discussed.