Psychotic-like cognitive biases in borderline personality disorder.

Whereas a large body of research has linked borderline personality disorder (BPD) with affective rather than psychotic disorders, BPD patients frequently display psychotic and psychosis-prone symptoms, respectively. The present study investigated whether cognitive biases implicated in the pathogenesis of psychotic symptoms, especially delusions, are also evident in BPD. A total of 20 patients diagnosed with BPD and 20 healthy controls were administered tasks measuring neuropsychological deficits (psychomotor speed, executive functioning) and cognitive biases (e.g., one-sided reasoning, jumping to conclusions, problems with intentionalizing). Whereas BPD patients performed similar to controls on standard neuropsychological tests, they showed markedly increased scores on four out of five subscales of the Cognitive Biases Questionnaire for Psychosis (CBQp) and displayed a one-sided attributional style on the revised Internal, Personal and Situational Attributions Questionnaire (IPSAQ-R) with a marked tendency to attribute events to themselves. The study awaits replication with larger samples, but we tentatively suggest that the investigation of psychosis-related cognitive biases may prove useful for the understanding and treatment of BPD.