Grey matter volume associations with personality functioning in a clinical cohort of female youths.

Borderline Personality Disorder (BPD) is a severe mental illness, although its neurobiological underpinnings remain largely unknown. Structural Magnetic Resonance Imaging (sMRI) in adolescents can offer insights into potential biomarkers to help advance early detection and targeted intervention. However, previous findings have been mixed, possibly due to clinical heterogeneity that may be better captured using a dimensional approach to personality functioning (PF). The current study explored grey matter volume (GMV) in youth with varying degrees of BPD pathology, and associations with dimensional PF. N = 93 females (14-21 years) comprising three groups (full-threshold BPD, sub-threshold BPD, and healthy controls) underwent sMRI and were assessed with the Semi-Structured Interview for Personality Functioning DSM-5 (STiP-5.1). Groups were combined to reflect dimensional personality pathology. Multiple linear regression analyses were conducted to determine associations between the STiP-5.1 total score, and each of its four elements with: (i) total GMV, (ii) GMV in individual brain regions defined by the Desikan-Killiany-Tourville atlas, (iii) selected regions of interest (ROIs). All analyses were statistically non-significant: STiP-5.1 total and total GMV (p = 0.61); STiP-5.1 total and individual brain regions (all corrected p values ≥0.82); STiP-5.1 total and ROIs (all corrected p values ≥0.91). Results were non-significant for each element, and a validity check using BPD criteria confirmed STiP-5.1 findings. We found no evidence of an association of dimensionally assessed PF with GMV in young females. The pursuit of clinical research efforts on other potential biomarkers using dimensional conceptualisations of PF may represent worthy endeavours.