A comparison of thought and perception disorders in borderline personality disorder and schizophrenia: psychotic experiences as a reaction to impaired social functioning

BACKGROUND Although previous studies suggest a high frequency of psychotic symptoms in DSM-IV Borderline Personality Disorder (BPD) there is currently no consensus on their prevalence and characteristics (type, frequency, duration, location etc.). Similarly, there are few papers addressing psychotic reactivity, the crucial aspect of BPD included in the ninth criterion for DSM-IV BPD, which remained unchanged in DSM-IV-TR and DSM-5. The purposes of the present study were to compare thought and perception disorders in patients with DSM-IV BPD and schizophrenia (SC), investigating their relationship with social functioning. METHODS Thought and perception disorders and social functioning over the previous two years were assessed by the Diagnostic Interview for Borderline Revised (DIB-R) and Personal and Social Performance scale (PSP) respectively in outpatients with DSM-IV BPD (n = 28) or DSM-IV SC (n = 28). RESULTS Quasi-psychotic thought (i.e. transient, circumscribed and atypical psychotic experiences) was more frequent in BPD (BPD = 82.1%, SC = 50%, p = 0.024); whereas true psychotic thought (i.e. Schneiderian first-rank, prolonged, widespread and bizarre psychotic symptoms) was more frequent in SC (SC = 100%, BPD = 46.4%, p < 0.001). However both types of psychotic features were prevalent in both groups. Non-delusional paranoia (e.g. undue suspiciousness and ideas of references) was ubiquitous but was more severe in BPD than SC patients (U(54) = 203.5, p = 0.001). In the BPD group there was a strong negative correlation between personal and social functioning and non-delusional paranoia (τ(28) = 0.544, p = 0.002) and level of personal and social functioning was a significant predictor of the severity of non-delusional paranoia only in the BPD group (β = -0.16, t(23) = 2.90, p = 0.008). CONCLUSIONS BPD patients reported less severe psychotic experiences with more frequent quasi-psychotic thought, less frequent true psychotic thought and more severe non-delusional paranoia than SC patients. Interpersonal functioning seems to predict non-delusional paranoia in BPD, which would validate the "stress-related paranoid ideation", included in the ninth diagnostic criterion for DSM-IV and DSM-5 BPD. PBD patients had higher scores on the psychotic experiences subscale that support the use of a dimensional assessment of the severity of thought and perception disorders, for example the Clinician-Rated Dimensions of Psychosis Symptom Severity introduced in DSM-5, Section III.