SU54. Shared Architecture of Dimensional Psychotic Symptoms Across Psychosis Spectrum Disorders: Impact on Functional Outcomes and Neurocognition

Abstract

Abstract Background: Psychosis spectrum disorders share significant overlap in symptoms, biomarkers, genetic factors, outcomes, and treatment response. Moreover, within each disorder, there is significant heterogeneity in symptom profiles, neurocognitive, and everyday functioning. This has lead to recent efforts, in line with the Research Domain Criteria (RDoC), to develop novel classifications based on dimensions that cut across traditional diagnostic boundaries. Whether there are homogeneous subgroups in bipolar disorder (BD) with distinct psychotic symptom profiles is unknown. Moreover, the impact of these subgroups on neurocognitive and everyday functioning is also unknown. We aimed to (1) cluster BD patients in homogeneous subgroups based on psychotic symptom profiles; (2) describe clinical, neurocognitive, and functional characteristics of each subgroup; and (3) test whether the subgroups extend across the psychosis spectrum (to patients with schizotypal personality disorder, SPD). Methods: Sample: 138 patients with BD I or II; 282 patients with SPD. Diagnosis: SCID, SIDP-IV. Psychotic symptoms: Schizotypal Personality Questionnaire, SPQ; a multidimensional measure of psychosis proneness that captures the full range from normal to abnormal, including subthreshold symptoms. Neurocognition: MATRICS Consensus Cognitive Battery (MCCB); Disability: World Health Organization Disability Assessment Schedule (WHODAS-II). With hierarchical cluster analyses, we tested for homogeneous subgroups in each sample (BD, SPD patients) based on the 9 SPQ subscales. To determine the impact of psychosis symptom profile on outcome, we used ANOVAs to compare the clusters on neurocognitive and everyday functioning. Results: In BD, we identified 3 clusters: (1) high propensity to positive symptoms, with significantly higher scores on ideas of reference, suspiciousness, unusual perceptions, odd beliefs, odd behavior, and odd speech than the other 2 clusters; (2) high negative symptoms and social dysfunction, with high scores on excess social anxiety and lack of friends; and (3) mild psychosis symptom profile, with the lowest scores across all SPQ subscales. Subgroup 1 (high positive symptoms) scored significantly lower in all cognitive areas (MATRICS composite, F = 3.72; df = 2; P = .027) and had lower premorbid IQ (F = 5.6; df = 124; P = .005) and significantly higher disability (WHODAS, F = 9.19; df = 2; P < .001) compared with the other 2 subgroups. In the SPD sample, we found a subgroup structure that was highly consistent with that described above. Conclusion: Our finding of a common structure of psychotic symptom profiles across different psychosis spectrum disorders supports the dimensional nature of the propensity to positive symptoms in a continuum across diagnostic boundaries. Our results further highlight the potential implications that this classification system may have on outcome.