SU49. Do Psychosis Biotypes Differ Across Traditional Schizophrenia Subtypes?

Abstract

Abstract Background: The diagnosis of schizophrenia included subtypes until the advent of DSM 5 when the subtypes were removed. The diagnosis of paranoid schizophrenia was often thought to reflect higher levels of functioning and cognition without prominent disorganized cognition and behavior and affective flattening. The traditional subtyping, however, has thus far received little biological validation. The Bipolar Schizophrenia Network of Intermediate Phenotypes (BSNIP I) study recently found people with psychosis could be divided into 3 groups based on biomarkers reflecting cognitive and sensorimotor functioning. In this study, we investigated whether the traditional subtypes map well to the biological subtyping of schizophrenia. Methods: The schizophrenia sample (N = 406), drawn from BSNIP I, was diagnosed using DSM-IV-TR SCID interviews and consensus diagnostic conferences. The 2 groups included a diagnosis of paranoid schizophrenia (n = 267) vs all other schizophrenia subtypes (disorganized, undifferentiated, catatonic, and residual) (n = 139). They were compared on cognition using the Brief Assessment of Cognition in Schizophrenia (BACS) and psychopathological ratings across Biotype 1 (n = 130), Biotype 2 (n = 119), and Biotype 3 (n = 101) and diagnostic subtype. Results: There were no clinically significant differences between the paranoid group and other schizophrenia subtypes on the Positive and Negative Symptom Scale (total Positive, Negative, and General Psychopathology subscales), Global Assessment of Functions, Montgomery Asberg Depression Rating Scale total depression score, and the Brief Assessment of Cognition in Schizophrenia total and individual cognitive test z score. All 3 biotypes were represented across all the DSM subtypes of schizophrenia. Biotype 1 was somewhat over-represented in the nonparanoid schizophrenia groups (57% of the disorganized group, 50% of the undifferentiated group, and 43% of the residual group [P = .026]), while the paranoid schizophrenia group was similarly distributed across all 3 biotypes (Biotype 1: 31%, Biotype 2: 37%, and Biotype 3: 32%). Conclusion: Traditional subtyping of schizophrenia based on symptomatology has been criticized for lack of biological validity. Our observations of no clinically significant differences between the paranoid and nonparanoid schizophrenia groups in cognition and symptoms are therefore not surprising. However, the relatively large preponderance of nonparanoid subgroups, especially of the disorganized subgroup in Biotype 1 is intriguing. Given that Biotype 1 has the most prominent brain structural and physiological alterations, it is possible that there are subtle neurobiological distinctions between the clinical subtypes of schizophrenia, which warrant further investigation.