Region-function specificity of structural brain alterations associated with non-suicidal self-injury in young people.

BACKGROUND

Non-suicidal self-injury (NSSI) is prevalent among young people and has been theoretically associated with mentalizing - the capacity to understand behavior in terms of mental states. However, the structural correlates of this capacity, and their relationship to different NSSI motivations, remain unknown.

METHODS

We examined the structure of brain regions implicated in mentalizing and region-function specificity in 173 young people (aged 10-24; NSSI group, n = 117; non-NSSI comparison group, n = 56). Structural MRI data (n = 132) were analyzed across seven a priori mentalizing network regions: inferior parietal lobule (IPL), supramarginal gyrus, medial orbitofrontal cortex, posterior cingulate cortex, superior temporal gyrus, and corpus callosum (CC) genu and splenium.

RESULTS

The NSSI group showed reduced CC splenium volume (d = 0.58, pFDR = 0.029) and IPL thickness (d = 0.42, pFDR = 0.029). A region-function specificity pattern emerged: IPL thinning was selectively associated with intrapersonal NSSI functions (emotion regulation and self-punishment; p = 0.005), whereas CC splenium volume reduction was selectively linked to interpersonal functions (social communication and help-seeking; p = 0.003).

CONCLUSIONS

These findings reveal regional structural reductions within mentalizing-related brain regions in NSSI, and suggest that distinct neurobiological pathways may underlie different NSSI motivations, with implications for function-based personalized interventions.