Looking at the bigger picture: Cortical volume, thickness and surface area characteristics in borderline personality disorder with and without posttraumatic stress disorder

•Cortical volume changes in borderline personality disorder inconsistently reported.•Comorbidity of posttraumatic stress disorder examined as a contributing factor.•Aimed to provide a more complete picture with additional surface area analyses.•No evidence of cortical volume alterations in BPD but hypergyrification detected.•No distinct patterns revealed regarding comorbid posttraumatic stress diagnosis. Borderline personality disorder (BPD) is a severe psychiatric disorder accompanied by multiple comorbidities. Neuroimaging studies have identified structural abnormalities in BPD with most findings pointing to gray matter volume reductions in the fronto-limbic network, although results remain inconsistent. Similar alterations were found in posttraumatic stress disorder (PTSD), a common comorbidity of BPD. Only a small number of studies have investigated structural differences in BPD patients regarding comorbid PTSD specifically and studies conducting additional surface analyses are scarce. We investigated structural differences in women with BPD with and without PTSD and non-patient controls. Automated voxel-based and region-based volumetric analyses were applied. Additionally, four surface-based measures were analyzed: cortical thickness, gyrification index, fractal dimension, and sulcus depth. Analyses did not identify cortical volume alterations in the fronto-limbic network. Instead, hypergyrification was detected in the right superior parietal cortex in BPD patients compared to non-patient controls. No distinction was revealed between BPD patients with and without PTSD. These findings underline the importance of a holistic investigation examining volumetric and surface measures as these might enhance the understanding of structural alterations in BPD.