Self-injurious behaviour (SIB) usually directly results in physical harm to an individual. Examples include hand biting, head slapping, picking at skin, gouging or striking the body or eating inedible material. Some researchers have begun to include stereotypy or repetitive movements in a definition of self-injurious behaviour, even if they do not result on tissue damage..
The presence of an autism spectrum disorder has been identified as a risk factor for developing self-injurious behaviour. SIB risk factors that have been studied people with learning disabilities have been the level of the learning disability, deficits in communication and the presence of specific genetic disorders.
More recent studies have begun to look at less common risk factors, for example, negative affect, hyperactivity and impulsivity.
The researchers in this USA study were interested in whether it was possible to identify predictors of self injurious behaviour in people with autism spectrum disorder.
What they did was identify a sample of 617 people with diagnoses of autism spectrum disorder from the US National Database of Autism Research.
They used structural equation modelling (a statistical technique which enables researchers to test causal relationships between variables)was used to assess whether impulsivity, hyperactivity, negative affect, severity of stereotypy, intellectual functioning or severity of autism symptoms predicted severity of SIB.
What they found was that impulsivity, intellectual functioning and stereotypy were the most highly predictive of increased self injurious behaviour.
Even when they controlled for severity of autism symptoms and level of intellectual functioning, they still found impulsivity and stereotypy to be significant predictors SIB.
They conclude that “high levels of impulsivity and stereotypy were significant predictors of SIB in a large and diverse sample of people with confirmed autism diagnoses.”
Predictors of self-injurious behaviour exhibited by individuals with autism spectrum disorder. Richman D et al., in Journal of Intellectual Disability Research, 57: 429–439