Borderline personality features and development of psychosis in an 'ultra high risk' (UHR) population: a case control study.

AIMS There is clinical uncertainty as to whether borderline personality disorder (BPD) traits in those with an 'at risk mental state' have an effect on the risk of 'transition' to psychosis. We aimed to investigate the relationship between baseline BPD features, risk of transition and type of psychotic disorder experienced. METHOD This is a case-control study of 'ultra high risk' (UHR) for psychosis patients treated at the clinic, between 2004 and 2007. 'Cases' were UHR individuals who made the 'transition' to full threshold psychotic disorder within 24 months; 'control' group was a matched UHR sample who had not developed a psychotic disorder at 24 months. Individuals were matched on time of entry to the clinic, age and gender. Diagnostic and statistical manual of mental disorders, fourth edition (DSM-IV) BPD features were assessed from clinical assessments using a structured instrument (Structured Clinical Interview for DSM-IV Axis II Disorder for BPD (SCID-II BPD)). Psychosis diagnosis following transition was rated from the clinical files using the operational criteria in studies of psychotic illness (OPCRIT) computer algorithm. The number of BPD traits and number with full threshold BPD were compared in those who developed psychosis and those who did not. RESULTS We analysed data from 48 cases and 48 controls. There was no statistically significant difference in the rate of transition to psychosis for those with baseline full-threshold BPD, compared with those without BPD. The number of BPD traits or number with full threshold BPD did not differ by psychosis diagnosis grouping. CONCLUSIONS Co-occurring BPD or BPD features does not appear to strongly influence the risk of short-term transition to psychosis or the risk of developing a non-affective psychotic disorder in this population.