Gene-Environment Interactions and the Functional Analysis of Challenging Behaviour in Children with Intellectural and Developmental Disabilities

Challenging behaviour displayed by people with intellectual and developmental disabilities represents a socially significant problem that severely restricts the quality of life of those who display such behaviours and their families. To date the study of life of those who display such behaviours has been characterised by genetic and environmental determinism. It seems likely that gene-environment interactions (GxE) may play a critical role in challenging behaviour displayed by some people with intellectual and developmental disabilities. The current thesis provides a conceptual and empirical examination of GxE as applied to challenging behaviour. The two empirical studies presented in the current thesis aimed to examine the hypothesis that genetic events may function as a type of motivating operation for challenging behaviour. In study one, parents of the children with FXS, SMS and a mixed etiology group of children with intellectual and developmental disabilities were interviewed about the function served by their child's challenging behaviour using the Questions About Behavioral Function (QABF; Matson & Vollmer, 1995) scale. Both within- and between-group differences were found. Children with FXS were less likely to display attention-maintained challenging behaviours; children with SMS were more likely to display pain-related challenging behaviours. In study two, experimental functional analysis methods were used to examine this question in a group of eight children with FXS and six children with SMS. No child with FXS displayed an attention-maintained response class of challenging behaviour. In contrast four children with SMS displayed a response class of challenging behaviour that was at least in part attention-maintained. The findings are discussed in light of the research literature on challenging behaviour in FXS and SMS. The findings are related to GxE and it is suggested that a developmental systems model, consistent with the principles of radical behaviourism, may help to move the field beyond the limitations of genetic and environmental determinism.