Diagnostic considerations
BPD is characterized by a chaotic emotional climate with impulsivity and instability of self-image, affect, and relationships. Most BPD symptoms, including psychosis, often are exacerbated by the perception of abandonment or rejection and other interpersonal stressors.1 Both BPD and schizophrenia are estimated to affect at least 1% of the general population.8,9 Patients with BPD frequently meet criteria for comorbid mental illnesses, including major depressive disorder, substance use disorder, posttraumatic stress disorder, anxiety, and eating disorders.10 Because psychotic symptoms can present in some of these disorders, the context and time course of these symptoms are crucial to consider.
Misdiagnosis is common with BPD, and patients can receive the wrong treatment for years before BPD is considered, likely because of the stigma surrounding the diagnosis.5 One also must keep in mind that, although rare, a patient can have both BPD and a primary psychotic disorder.11 Although a patient with schizophrenia could be prone to social isolation because of delusions or paranoia, BPD patients are more apt to experience intense interpersonal relationships driven by the need to avoid abandonment. Manipulation, anger, and neediness in relationships with both peers and health care providers are common—stark contrasts to typical negative symptoms, blunted affect, and a lack of social drive characteristic of schizophrenia.12
Distinguishing between psychosis in BPD and a psychotic disorder
Studies have sought to explore the quality of psychotic symptoms in BPD vs primary psychotic disorders, which can be challenging to differentiate (Table 1). Some have found that transient symptoms, such as non-delusional paranoia, are more prevalent in BPD, and “true” psychotic symptoms that are long-lasting and bizarre are indicative of schizophrenia.13,14 Also, there is evidence that the lower levels of interpersonal functioning often found in BPD are predictive of psychotic symptoms in that disorder but not in schizophrenia.15
Auditory hallucinations in patients with BPD predominantly are negative and critical in tone.4 However, there is no consistent evidence that the quality of auditory hallucinations in BPD vs schizophrenia is different in any meaningful way.16 Because of the frequency of dissociative symptoms in BPD, it is likely that clinicians could misinterpret these symptoms to indicate disorganized behavior associated with a primary psychotic disorder. In one study, 50% of individuals with BPD experienced auditory hallucinations.11 Differentiating between “internal” or “external” voices did not help to clarify the diagnosis, and paranoid delusions occurred in less than one-third of patients with BPD, but in approximately two-third of those with a diagnosis of schizophrenia.
The McLean Study of Adult Development, a longitudinal study of BPD patients, found that the prevalence of psychotic symptoms diminished over time. It is unclear whether this was due to the spontaneus remission rate of BPD symptoms in general or because of effective treatment.13
Psychotic symptoms in BPD seem to react to stress and increase in intensity when patients are in crisis.17 Nonetheless, because of the prevalence of psychosis in BPD patients and the distress it causes, clinicians should be cautioned against using terms that imply that the symptoms are not “true” or “real.”3