Sensory Processing in Body-Focused Repetitive Behaviors

Abstract

Body-focused repetitive behaviors (BFRBs) such as hair pulling and skin picking are common practices that are part of ordinary grooming, but can proliferate excessively into maladaptive habits. Despite their negative consequences, affected individuals often experience great difficulty in stopping pulling/picking and report strong urges and hedonic reward associated with symptoms. Unfortunately, the psychobiological mechanisms underlying sensory features of BFRBs have been insufficiently studied. The current study aimed to explore potential sensory processing abnormalities in adults with Trichotillomania and Excoriation Disorder using several self-reported instruments and a vibrotactile behavioral battery. A total of 46 adults with either Trichotillomania or Excoriation Disorder were recruited, along with an age-matched sample of 46 healthy control participants. Participants completed clinician-rated interviews regarding their symptom severity and self-report instruments regarding interoceptive awareness and sensory gating. The vibrotactile battery consisted of several tests that assessed reaction time, sensorimotor integration, detection threshold, feed-forward inhibition, lateral inhibition, temporal processing, and duration discrimination. Persons with BFRBs reported increased interoceptive awareness, a greater propensity to worry about their body states, and less trust in their own body. In addition, the BFRB group reported greater perceptual inundation, sensory distractability, overinclusion, and a propensity to experience sensory abnormalities while fatigued or distressed. Persons with BFRBs did not display behavioral deficits in sensorimotor integration, quickly adapting lateral inhibition, temporal processing, or duration discrimination. However, the BFRB group had lower tactile thresholds and deficient feed-forward inhibition. Deficient feed-forward inhibition was correlated with skin picking severity. These findings indicate that increased sensitivity to sensory stimuli and an inability to filter out excess sensory input is associated with a propensity to engage in BFRBs, perhaps as a method of distracting oneself from an aversive perceptual state.