A neurobiological evaluation of soft touch training for patients with skin-picking disorder

BACKGROUND: Individuals with skin-picking disorder (SPD) display reduced neural sensitivity to slow/soft touch. This functional magnetic resonance imaging (fMRI) study investigated the effects of Soft Touch Training (STT) on neural correlates of touch processing and SPD symptoms. METHOD: Females with a primary diagnosis of SPD (n = 57) were randomly assigned to receive either four weeks of STT (guided soft brushing of selected skin regions) or Progressive Muscle Relaxation (PMR) training (guided tensing and relaxing of selected muscle regions). The app-assisted intervention consisted of 15-minute daily training sessions at home. Before and after the four-week intervention, the two groups participated in a standardized tactile stimulation procedure during fMRI (affective vs nonaffective touch of the forearm). Intervention-based changes in subjective and neural responses to the tactile stimulation as well as SPD severity were compared between the groups. RESULTS: STT increased the pleasantness ratings for (affective) touch administered during fMRI, which was accompanied by decreased activation in the parietal operculum (PO) and supramarginal gyrus (SMG), as well as increased PO-SMG connectivity. These findings possibly reflect normalized affective touch processing due to STT. Both interventions (STT and PMR) reduced SPD severity. CONCLUSIONS: This study demonstrated that a brief app-assisted touch training can change the experience of receiving touch from others and the associated brain activity and connectivity. Adaptations of the training relating to duration/ frequency of sessions might enhance its effectiveness.