Environmental, physiological and neural bases of skin picking in Prader-Willi syndrome

Many people with Prader-Willi Syndrome (PWS) frequently engage in severe skin picking behavior, often causing open wounds and sores that can become infected. Why do people with PWS do this? How often and under what circumstances does it occur? Are people with PWS more likely to exhibit skin picking when they are bored or anxious? Does the skin picking hurt? Or do individuals with PWS have a high pain tolerance? In other words, is the problem caused by environmental, physiological, or neural factors? As in most disorders, it is crucial to understand the underlying cause of the symptoms because it ultimately helps to identify appropriate treatments. In this research project, we therefore will investigate the possible causes of skin picking in PWS using state-of-the-art behavioral and neuroimaging methods. These methods will help us to develop and implement individualized treatments for this behavior. For example, if we find that for some people, environmental processes are involved in skin picking, behavioral management techniques may be implemented (e.g., if skin picking occurs when the individual is left alone without appropriate competing activities, environmental enrichment may prove useful). If we find that skin picking for some people is associated with aberrant neural processes, pharmacological approaches to treatment may be required (e.g., if skin picking occurs because it activates brain centers that release neurotransmitters, such as endogenous opioids, medications that block or reduce their release may be prescribed). Finally, if we find that for some people, both environmental and neural processes are involved, a combination of behavioral and pharmacological treatments may be required. To our knowledge, this will be the first study to identify the potential causes of skin picking in PWS and will pave the way for new “disease-specific” treatments for this distressing, stigmatizing, and disabling behavior problem in PWS.

Research Outcomes: Project Summary

In the screening phase of the study, we identified 55 individuals with PWS (28 DEL, 23 UPD, 4 unknown subtype) who showed skin picking behavior. From interviews with parents, skin picking was most often reported to occur on a regular (daily) basis and to be targeted to the extremities (i.e., hand, finger, foot, toe) and the head. Just under half of all cases were rated as “high risk” on the Self-injury Trauma Scale. No differences were found in terms of form, frequency or severity of skin picking between DEL and UPD subtypes. Taken together, these data suggest that skin picking is a significant problem for individuals with PWS.

In the assessment phase, we found that skin picking occurred primarily when the individual was alone or had nothing to do. Skin picking rarely occurred with the individual was occupied or engaged in social activities. If surface tissue damage (e.g., bleeding) occurred, skin picking appeared to result in an increase in heart rate rather than a decrease. These data suggest that skin picking in PWS may serve a self-stimulatory function and that methods to keep the individual occupied, or at least compete with the sensory stimulation, will likely result in decreased episodes. Environmental factors are therefore an extremely important component of skin picking in PWS.

Research Outcomes: Publications

Neural correlates of self-injurious behavior in Prader-Willi syndrome. Klabunde M, Saggar M, Hustyi KM, Hammond JL, Reiss AL1, Hall SS.  Human Brain Mapping. 2015 Oct;36(10):4135-43.

Experimental functional analysis of severe skin-picking behavior in Prader-Willi syndrome. Hall SS, Hustyi KM, Chui C, Hammond JL. Research in Developmental Disabilities. 2014 Oct;35(10):2284-92.

An analysis of the topography, severity, potential sources of reinforcement, and treatments utilized for skin picking in Prader-Willi syndrome. Hustyi KM, Hammond JL, Rezvani AB, Hall SS. Research in Developmental Disabilities. 34(9):2890-9, 2013.

Examining the relationship between heart rate and problem behavior: a case study of severe skin picking in Prader-Willi syndrome. Hall SS, Hammond JL, Hustyi KM. American Journal on Intellectual and Developmental Disabilities. 118(6):460-74, 2013.