Brain mechanisms for processing caress-like touch in skin-picking disorder

Area of Science:

• Neuroscience
• Psychiatry
• Dermatology

Background:

• Skin-picking disorder (SPD) involves repetitive skin picking, often leading to tissue damage.
• The sensory experience of touch, particularly caress-like stimuli, is poorly understood in SPD.
• C-tactile afferents are involved in processing pleasant, gentle touch.

Purpose of the Study:

• To investigate neural responses to caress-like touch in females with SPD using functional magnetic resonance imaging (fMRI).
• To compare brain activation patterns between individuals with SPD and healthy controls during tactile stimulation.
• To explore the relationship between tactile processing, sensory ratings, and the urge to pick skin in SPD.

Main Methods:

• Seventy females with SPD and 62 healthy females underwent fMRI scans.
• Participants received CT-optimal (3 cm/s) and non-optimal (30 cm/s) brushing on their forearms.
• Subjective ratings of pleasure, arousal, and urge to pick were collected post-stimulation.

Main Results:

• SPD patients showed greater activation in parietal regions (supramarginal/angular gyrus) during CT-optimal touch compared to controls.
• Controls exhibited deactivation in the middle/inferior frontal cortex, which was absent in the SPD group.
• Being touched was rated as less pleasant, more arousing, and increased the urge to pick skin in individuals with SPD.

Conclusions:

• SPD is associated with dysfunctional processing of gentle, caress-like touch.
• Altered activation in frontal and parietal attentional control regions may underlie sensory processing deficits in SPD.
• Findings contribute to understanding the neurobiological basis of tactile dysfunction in skin-picking disorder.