Neural markers in excoriation disorder: Systematic review of neuroimaging evidence.

Excoriation disorder (ExD), or skin picking disorder, is a chronic body-focused repetitive behavior (BFRB) that leads to severe tissue damage, disfigurement, and psychological distress. Despite its prevalence, the neurobiological etiology of ExD remains poorly understood, hindering early diagnosis and intervention. This systematic review synthesizes findings from neuroimaging studies reporting on neural correlates of ExD. A comprehensive search of PubMed, PsycINFO, and Web of Science identified 18 studies meeting inclusion criteria. Across 784 ExD participants and 530 controls, consistent patterns emerged in brain regions related to sensorimotor inhibition, habit formation, and perceptual-affective interaction. Structural MRI showed smaller volumes in the orbitofrontal cortex, insula, and cerebellum, but increased size of nucleus accumbens, associated in previous studies with deficient inhibitory control. Task-related fMRI showed increased activation in frontal and parietal regions but diminished engagement of posterior cerebellar-prefrontal circuits during sensorimotor coordination, and amplified insula and amygdala responses to aversive stimuli. Resting-state fMRI linked ExD symptom severity with reduced supplementary motor and prefrontal connectivity. The findings consistently point to deviation in networks subserving sensorimotor-emotional integration, one of the earliest stages of brain-behavior development. A hypothesis of ExD as a developmental disorder is suggested, guiding future research to early markers of detection and prevention.