Sleep-Impulsivity-Behaviour (SIB) Study: examining mechanisms underpinning self-harm in children with autism and intellectual disability

Self-harm, such as biting, scratching, head banging and body punching, occurs at very high rates in children with autism and intellectual disability (ID). As many as 1 in 2 children with autism and ID will self-harm, and in most cases these behaviours persist beyond childhood. Unfortunately, self-harm is a primary cause of family stress, and often leads to placement breakdown resulting in children requiring specialist residential placements away from the family home.

Our existing understanding of self-harm in children with autism and ID suggests that interactions in the environment and internal sensory experiences can cause and maintain self-harm. For example, asking a child to complete a school-based task may lead to the child biting themselves; a concerned adult may then briefly remove the task to comfort and protect the child. Over time, a subtle learning process occurs which ingrains these interactions between the child and the environment around them. This learning process makes self-harm more likely, and can also make it more severe. However, whilst this model of self-harm is helpful, it does not identify underlying causes for self-harm beyond these learning processes. Additionally, interventions based on this model can typically only be started after self-harm has already become a learnt behaviour. Our work will uncover causes that drive this learning process, and lead to interventions that target causes to prevent self-harm from becoming established.

Based on our previous research, the Sleep-Impulsivity-Behaviour (SIB) Study investigates two potential causes or drivers of self-harm. First, we examine a fundamental brain-based mechanism. Our work suggests that children who self-harm have problems stopping and starting their own behaviour; this brain-based mechanism is called inhibition. However, current assessments of inhibition are often too lengthy or too difficult for children with autism and a co-occurring ID. We have developed new, specialised tests of inhibition that can be used with children with autism and ID, allowing us to test whether problems with inhibition are a fundamental cause of self-harm. These new tests are quick and easy play-based games, and we will compare performance on these games in children with autism and ID who do, and do not show self-harm.

Second, we investigate whether poor sleep makes self-harm more likely. We are particularly interested in whether specific sleep difficulties, for example problems with falling asleep, problems with staying asleep, or problems with sleeping at the wrong time in a 24-hour cycle, lead to more frequent and more severe self-harm. We will use wrist worn sleep devices to directly assess children's sleep, providing accurate information about sleep timing and sleep duration. We will use advanced statistical modelling to link children's sleep data with information about their self-harm, collected by parents/carers via a mobile phone App. Our analysis will provide conclusive information about the influence of sleep on self-harm.

To complete the SIB Study, we will bring together these two strands of work. In typically-developing children and adults, sleep is known to influence inhibition. Therefore, we think that inhibition may explain part of the relationship between poor sleep and self-harm. In our final study, we will test this idea by running a sleep intervention to improve sleep in children with autism and ID. We will measure inhibition and self-harm to see if improvements in inhibition explain some of the changes in self-harm. Together, all three of these studies will show whether poor inhibition and poor sleep cause self-harm in children with autism and ID. Findings will inform interventions for self-harm, with sleep and inhibition as new, preventative intervention targets. Through our extensive links with clinical services and policy makers, we will ensure that the findings of this project quickly and effectively influence clinical practice.

Self-harm occurs in 50% of children with autism and intellectual disability (ID). These behaviours are severe, persistent and associated with deleterious consequences for children and their families. Despite poor outcomes, only 0.02% of published autism papers are concerned with behaviours such as self-harm, and therefore understanding of mechanisms underpinning self-harm remains limited.

The prevailing model of self-harm in children with autism and ID is derived from an associative learning account. Whilst this model describes observable clinical phenomena in the form of behaviour-contingency relations, it cannot account for child characteristics associated with the presence and severity of self-harm. Hence the likely cognitive and psychobiological mechanisms underpinning self-harm have not been delineated. Our project targets these risk markers, specifically impulsivity and poor sleep, to identify contributory mechanisms and uncover viable preventative intervention targets for this at-risk population.

We will recruit a large cohort of children with autism and ID, and contrast performance on novel, robust measures of executive functioning to determine whether fundamental deficits in response inhibition account for the presence and severity of self-harm. We will also apply direct measurement of sleep phenomenology via actigraphy, to model the independent contribution of specific sleep parameters and circadian sleep/wake patterns to the presence, severity and timing of self-harm. Finally, we will apply experimental methods, systematically manipulating sleep to evaluate the mediating contribution of impaired response inhibition to the relationship between poor sleep and self-harm. These studies will extend the existing operant account of self-harm, incorporating cognitive and psychobiological risk markers to increase model precision and highlight targets for preventative intervention.

Impact from the Sleep-Impulsivity-Behaviour (SIB) Study is planned to be widespread, affecting the following beneficiaries.

Clinicians and policy-makers: The SIB study will have impacts for clinicians and policy-makers working with children with autism and ID. The data generated in the SIB Study will inform understanding of cognitive strengths and weaknesses, and atypical sleep profiles in this group. Specifically, the SIB study will highlight potential intervention targets (inhibition, sleep) to improve self-harm outcomes in this high-risk group. These data will inform policy-makers of the high clinical need, robust risk markers and potential avenues for effective intervention in children with autism and ID. We plan to ensure this impact through the PI, Co-I's and International Collaborator's continued engagement and contribution to policy making forums.

Healthcare and economy: Our recent policy briefing (Early intervention for children with learning disabilities whose behaviour challenges. Briefing Paper) highlighted the potential cost-saving impact of early, preventative interventions in self-harm and other challenging behaviours. These economic impacts are critical given the high financial cost of inpatient hospital admission for children with intellectual disability (estimated at £46 million per annum in the UK). However, early intervention efforts are limited by poor delineation of risk markers and therefore non-specific target populations and treatment precision. The SIB Study will quantify the strength and underlying mechanisms for two central risk markers for self-harm (impulsivity and poor sleep). These data will evidence the utility of these risk markers as part of a comprehensive early intervention strategy, which has the potential for significant healthcare and economic cost saving.

Industry partnerships: The PI is working with industry partners, providing early stage support in several large-scale pharmaceutical trials to improve outcomes in a range of neurodevelopmental and neurogenetic conditions. A key challenge for such trials is to identify treatment targets and mechanisms that underpin later behavioural outcomes. Both sleep and cognition have been highlighted as putative pharmaceutical targets. However, it remains still challenging to accurately measure such outcomes in children with severe-profound ID. The SIB Study will generate protocols for sleep and executive function measurement in these groups, which may have later utility as outcome tools for pharmaceutical trials.

Capacity building: The proposed project will have an impact on the PDR and the PI's career progression. The PDR will gain skills in applied research methods, and will develop their skills to communicate with both academics (through presentations in international conferences) as well as the general public (via participation in the events above). The PI is an early career researcher who began her first permanent academic post at the University of Birmingham in June 2017. This project will allow the PI to initiate novel research networks with scientists in related areas, develop her experience in managing a research team, and set the ground for future international collaborative scientific endeavours.