[Hallucinations and borderline personality disorder: a review]

Hallucinations constitute understudied symptoms in borderline personality disorders (BPD), which can be observed in about 30% of the patients, essentially in the auditory modality. Most of these experiences are transitory, triggered by intermittent stressors, but chronicity remains a major cause of concern. In order to better circumscribe hallucinations in BPD, we summarized the literature on this particular phenomenon.

We conducted a review using Medline, Scopus and Google Scholar databases up to March 2013, using the following keywords combinations: "borderline personality disorder", "hallucinat*" and "psychotic symptoms". Papers were included in the review if they were published in an English or French language peer-reviewed journal; the study enrolled patients with BPD; and the diagnosis was made according to the Diagnostic and Statistical Manual (DSM) criteria. Fifteen studies published between 1985 and 2012, merging a total of 635 patients, were retained.

The hallucinatory experiences observed in BPD appeared phenomenologically similar to those described in the schizophrenia spectrum in terms of vividness, duration, spatial localization, beliefs about malevolence or omnipotence. Conversely, the hallucinatory content appeared more negative and potentially more distressful. Crucially, this literature search also revealed that these symptoms have long been regarded as "pseudo-hallucinations" (or "hallucination-like symptoms"). This concept was judged of poor scientific validity, inducing stigma for BPD patients in that it casts doubt on the authenticity of these experiences while disqualifying the related distress. This situation points out that research should focus more on understanding hallucinations in BPD than questioning their existence. Interestingly, recent comorbidity studies reopened a 40-year debate on the potential links that may exist between BPD and psychosis. Initially considered as a para-psychotic disorder, BPD was effectively redefined as an independent category by Otto F. Kernberg, leading to the DSM-III definition, excluding any psychotic symptom. However, hallucinations per se remain insufficient to diagnose schizophrenia, while comorbid substance use disorders as well as mood disorders, cannot explain all the hallucination occurrences in BPD. By referring to the "psychotic-reactivity-to-stress" framework, we proposed to understand hallucinations in BPD in relation to a hyperactivity of the hypothalamic-pituitary-adrenal axis and of the dopaminergic system under stress. Childhood trauma may have a central role in such a model. The prevalence of childhood trauma is high in BPD but this factor was also evidenced strongly linked with hallucinations in non-clinical populations. Comparisons are finally made and discussed between hallucinations occurring in BPD and those observed in posttraumatic stress disorder, another frequent comorbid disorder.

Almost a third of patients with BPD experiences hallucinations, and future studies will have to clarify the pathophysiology of this symptom, still poorly understood. Both the models of psychotic-reactivity-to-stress, as well as the role of childhood trauma in the context of a gene X environment interaction, appear to be promising cues for future research.