Introduction: Patients with borderline personality disorder (BPD) suffer from severe social impairments and interpersonal problems. Social touch can provide comfort and facilitate the maintenance of social bonds, and preliminary evidence indicates a negative evaluation of social touch in patients with BPD. However, the neural mechanisms underlying aberrant touch processing in BPD and its role for social impairments are still unclear.
Methods: We recruited 55 BPD patients and 31 healthy controls and used functional magnetic resonance imaging to probe neural responses to slow (i.e., C-tactile [CT]-optimal; affective) and fast (i.e., CT-suboptimal; discriminative) touch before and after 4 weeks of a residential dialectical behavior therapy (DBT) program. In addition to assessing BPD symptoms and interpersonal problems, we evaluated touch allowance maps and the attitude toward social touch.
Results: BPD patients showed a comprehensive negative bias toward social touch before the DBT, evident in a significantly more negative attitude toward and reduced comfort zones of social touch compared to healthy controls. Activation in the posterior insular cortex in response to CT-optimal touch was significantly reduced and correlated with the severity of interpersonal problems in BPD patients. Despite significant improvements in overall BPD symptom load, dysfunctional social touch processing persisted after 4 weeks of DBT, indicating trait-like disturbances in BPD.
Conclusions: An impaired insula-mediated integration of affective and sensory components of touch may constitute a clinically relevant biological signature of the complex interpersonal problems in BPD.
Keywords: Borderline personality disorder; Dialectical behavior therapy; Functional magnetic resonance imaging; Interpersonal problems; Social touch.
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