Is Borderline Personality Disorder a Precursor of Schizoaffective Psychosis? A Twenty-Year Retrospective Study of More than 400 Patients from a Psychiatric Hospital

Background: Both borderline personality disorder (BPD) and schizoaffective disorder (SAD), as well as their potential connection, remain controversial diagnoses. To explore whether BPD may be part of the spectrum of SAD, we conducted a longitudinal study of a large clinical cohort of patients with BPD. Methods: We assessed the diagnostic trajectories of 402 patients with BPD in a 20-year retrospective study based on electronic clinical records from a psychiatric hospital using ICD-9 diagnoses. Data were descriptively examined on concurrent and sequential diagnoses in patients with BPD. For the classification of SAD, a proxy diagnosis was used. Results: The study population showed a high prevalence of affective disorders and a high frequency of concurrent diagnoses of affective–BPD. Together, stable BPD, stable affective disorder sequences and transitions from affective disorders to BPD represented 79% of all longitudinal trajectories. Conclusion: These findings should be considered exploratory and do not allow confirmation or refutation of the hypothesis that BPD serves as a precursor, prodrome, or component within the spectrum of SAD.