An investigation of impulsivity in young adults exhibiting body-focused repetitive behaviors

- Nail biting and skin picking do not predict poor inhibition(Stop Signal Task, SST).
- Comorbid nail biting and skin picking predicts longer SST reaction times.
- Comorbid nail biting and skin picking predicts increased stop signal delay.
- Nail biting predicts higher discounting rates(Monetary Choice Questionnaire, MCQ).
- Nail biting and skin picking severity are related to SST and MCQ performance.

Prefatory research provides rationale for the body focused repetitive behavior cluster (BFRB; e.g. skin picking, nail biting), however little is known concerning the etiologies of these behaviors. While research suggests impulsivity impairment amongst several BFRBs, research has yet to examine multiple impulsivity domains or examine impulsivity within a nail biting or comorbid BFRB context. As such, this study sought to examine two facets to impulsivity (motor inhibition and delay discounting) amongst young adults exhibiting subclinical BFRBs (nail biting, skin picking, comorbid nail biting and skin picking). One hundred and thirty-two participants (37 demonstrating nail biting, 36 demonstrating skin picking, 19 demonstrating comorbid skin picking and nail biting, 40 controls) completed an assessment battery including self-reports (Monetary Choice Questionnaire, MCQ) and neurocognitive measures (Stop Signal Task, SST). Analyses revealed that individuals exhibiting comorbid BFRBs demonstrated significantly increased SST reaction time (controlling for stress) and stop signal delay (controlling for stress and medication use) compared to controls. Additionally, nail biters demonstrated significantly increased discounting (controlling for age) of MCQ medium and large rewards compared to controls. Group classification did not significantly predict remaining outcomes. Analyses indicated relationships between BFRB severity and task performance. Findings suggest important insights into the neurobiology of BFRBs.