Self-injury, aggression and destruction in children with severe intellectual disability: incidence, persistence and novel, predictive behavioural risk markers

Background: A risk informed, early intervention strategy for self-injurious, aggressive and destructive behaviours in children with severe intellectual disability is gaining support. The aims of this study were to establish the cumulative incidence and persistence of self-injury, aggression and destruction and the relationship between these behaviours and two potentially predictive behavioural risk markers (repetitive behaviour, and impulsivity and overactivity) in children at high risk. Methods: In a longitudinal design self-injury, aggression and destruction were assessed by teachers of 417 children with severe intellectual disability on two occasions separated by 15-18 months. Results: Aggression, destruction and self-injury were persistent (69%, 57% and 58% respectively). Repetitive and restricted behaviours and interests (RRBI) and overactivity/impulsivity (O/I) were significantly associated with aggression (O/I OR = 1.291, p<.001), destruction (RRBI OR 1.201, p= .013; O/I OR 1.278, p<.001) and/or self-injury (RRBI, OR 1.25, p= .004; O/I OR = 1.117, p<.001). The relative risk of the cumulative incidence of self-injury, aggression and destruction was significantly increased by repetitive and restricted behaviours and interests (self-injury 2.66, destruction 2.16) and/or overactivity/impulsivity (aggression 2.42, destruction 2.07). Conclusions: The results provide evidence that repetitive and restricted behaviours and interests, and overactivity/impulsivity, are risk markers for the onset of self-injury, aggression and destruction within the already high risk group of children with severe intellectual disability.