Interpersonal Trust: Development and Validation of a Self-Report Inventory and Clinical Application in Patients With Borderline Personality Disorder.

Based on typical everyday trust situations, a short and ecologically valid self-report instrument for the assessment of interpersonal trust was developed (Interpersonal Trust Scenario Questionnaire [ITSQ]). Data from 1,359 clinical and nonclinical participants were analyzed to examine psychometric properties and group differences. The authors assessed interpersonal trust in patients with borderline personality disorder (BPD), patients with major depressive disorder, and patients with social anxiety disorder. Lastly, the relationship between interpersonal trust and the perceived quality of the therapeutic alliance was examined. The ITSQ showed satisfactory reliability (Cronbach's α = 0.72). Convergent validity and discriminant validity were obtained for correlations with a hypothetical trust game, another interpersonal trust scale (KUSIV-3), risk propensity, optimism and pessimism, and the HEXACO-60. Patients with BPD showed the lowest interpersonal trust scores of all groups. Interpersonal trust and the perceived quality of the therapeutic alliance were significantly associated only in the group of patients with BPD.