Testosterone in patients with borderline personality disorder: from hair analyses to social behavior.

Clemens Kirschbaum provided the important inspiration for our team to extend the assessment of steroid hormones beyond blood and saliva samples to include hair analyses. This enabled the investigation of the effects of long-term, cumulative steroid hormone secretion. This novel methodological perspective provided particularly compelling for the study of long-lasting stress-related mental disorders, such as borderline personality disorder (BPD). In an initial study, we found unaltered hair cortisol but increased hair testosterone in women with BPD. Notably, the latter finding inspired us to further investigate the role of testosterone in this patient population. Across subsequent studies, we replicated the finding of increased basal testosterone in a large sample of patients with BPD and identified associations with prosocial behavior and symptom burden, particularly internalizing symptoms. The present paper reviews these and related findings of testosterone in BPD and discusses their clinical relevance and implications for further research.