Associations between personality organization, personality structure, mentalization, and inflammatory markers (IL-6 and CRP) in young adults with personality disorders

Background: Maladaptive interpersonal patterns that significantly impair functioning are central to personality disorders (PDs). A paradigm shift towards dimensional models highlights the importance of severity. However, the relationship between the dimensional concepts of personality organization, personality structure, mentalization, as well as biological markers IL-6 and CRP, remains largely unexplored. Methods: This exploratory cross-sectional analysis draws on data from a longitudinal study with a subsample of 28-day clinic patients (mean age = 22, SD = 2; 64% female, 29% male, and 4% diverse) with impaired personality functioning. Convergent validity was assessed between the Structured Interview for Personality Organization (STIPO-R), the Inventory of Personality Organization (IPO-16), the OPD Structure Questionnaire (OPD-SQS), and the Mentalization Questionnaire (MZQ). Interleukin-6 (IL-6) and C-reactive protein (CRP) were measured in serum, with BMI included as a covariate. Multiple testing corrections were applied. Results: Significant positive correlations were found between several STIPO-R dimensions and IPO-16, OPD-SQS, and MZQ dimensions. Furthermore, STIPO-R dimensions were positively correlated with higher IL-6. CRP was positively correlated with the OPD-SQS dimension shaping contact and the MZQ dimension emotional awareness. After controlling for BMI, associations with IL-6 remained significant, but not those with CRP. Conclusion: This cross-sectional study demonstrates that the STIPO-R is a reliable and valid instrument for the evaluation of PDs in adolescent patients. Notably, the inflammatory marker IL-6 showed significant correlations with dimensions of personality organization impairment in young adults, whereas the influence of BMI explained associations with CRP. These findings suggest that inflammatory processes could be a significant factor in the pathophysiology of personality disorders and open possibilities for integrating biomarkers into diagnostics and therapeutic approaches. Both the inflammatory markers and the STIPO-R could be helpful for treatment planning, monitoring the course of therapy, and making prognostic assessments. Future studies should include larger patient groups, healthy control subjects, and additional biomarkers to investigate dimensional diagnostic approaches further.