People with borderline personality disorder (BPD) tend to distrust others. We hypothesized that acetaminophen might reduce distrust in people with high BPD features because disordered affective responses are partially responsible for the interpersonal difficulties of people with BPD features, and acetaminophen has been shown in multiple studies to reduce negative affect. Using a double-blind, parallel-arm design, 284 young adult participants were administered either acetaminophen (1,000 mg; acute) or placebo and subsequently completed an economic trust game. BPD features were assessed with the Personality Assessment Inventory–Borderline Features scale. Participants with elevated BPD features showed less trust in their partners in the placebo condition but increased trust in the acetaminophen condition. Acetaminophen did not change expectations of trustee’s trustworthiness and did not impact trusting behavior in participants low in BPD features. Our results indicate that acetaminophen may reduce the behavioral distrust exhibited at high levels of BPD features.
