Understanding self-restraint and self-injurious behaviour in children with autism and/or intellectual disability

Marlow, Katherine Elizabeth ORCID: 0000-0003-4788-0984 (2024). Understanding self-restraint and self-injurious behaviour in children with autism and/or intellectual disability. University of Birmingham. Ph.D.

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Abstract

Background: Self-restraint, the self-initiated restriction of one’s own body movements, is observed alongside self-injurious behaviour in populations with neurodevelopmental conditions. Self-restraint behaviours are understood through mechanisms of operant learning, however a purely operant account cannot adequately account for the presence of both self-injury and self-restraint. To bridge this theoretical gap, two complementary hypotheses have been proposed: the compulsivity and inhibitory control accounts. Thus far, these accounts are limited by a paucity of research, lack of focus on self-restraint measurement and reliance on indirect measures of inhibitory control. Therefore, this thesis aimed to describe self-restraint in high-risk groups, and test prevailing theoretical accounts of this behaviour across different parameters of self-restraint.
Method: A comprehensive systematic review of the existing literature provided meta-analytic estimates of the prevalence of self-restraint, self-restraint topographies, and quantified the size of association between self-restraint and putative correlates, including self-injury. A large-scale cross-syndrome survey examined transdiagnostic correlates of self-restraint, including compulsivity and anxiety, using a dimensional measurement approach. The presence and intensity of self-restraint displayed by autistic children with intellectual disability was assessed using naturalistic observational techniques. Finally, the feasibility of a novel battery of direct executive function tasks was assessed, and tasks were administered alongside indirect measures to examine the compulsivity and inhibitory control accounts.
Results: The pooled prevalence estimate of self-restraint in autistic individuals and/or those with intellectual disability was 39%, and self-restraint and self-injury shared a significant moderate association. Compulsivity and anxiety were unique predictors of self-restraint across neurodevelopmental conditions, over-and-above confounding variables. Autistic children with intellectual disability displayed a high prevalence of self-restraint, with intensity of self-restraint varying both between and within topographies. The direct executive function tasks were deemed developmentally-appropriate for autistic children with varying degrees of intellectual disability. Indirect measures of executive function more closely associated with self-restraint than direct measures, with self-injury severity moderating the relation between poor executive function and greater self-restraint intensity.
Conclusions: The prevalence of self-restraint within populations who self-injure was consistently high, however the presence of ‘multi-parameter’ self-restraint was lower. Younger age, greater autism characteristics and lower adaptive functioning were important demographic factors associated with presence, topographies and intensity of self-restraint. Findings of impulsivity uniquely predicting self-restraint at high levels of self-injury, and of compulsivity and anxiety predicting self-restraint after accounting for covariates, allowed for proposal of a novel, integrated compulsivity/inhibitory control account. This suggests that ‘impulsive’ self-injury increases anxiety/arousal, leading to the emergence of habitual
‘compulsive’ self-restraint. Future research is required to examine this integrated theory.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):