Background: The specificity of Schneider’s first-rank symptoms to schizophrenia in comparison to other psychotic disorders is unclear. We compared the duration and severity of first-rank symptoms across three different diagnoses using the Lifetime Dimensions of Psychosis Scale (LDPS).
Methods: All data was collected as part of the Bipolar Schizophrenia Network of Intermediate Phenotypes-2 (BSNIP-2) study. A trained clinician rated participants on the duration and severity of psychosis symptoms using the LDPS. Participant scores from Control Delusions (S1), Conversing/commenting/continuous hallucinations (S3), and Abnormal perception of thought (S4) were combined to create overall first-rank symptom (FRS) scores for duration and severity.
An ANOVA was computed and followed with a Fisher’s Least Significant Difference post-hoc test to determine significant differences in S1, S3, S4, and overall FRS scores across three different diagnoses: schizophrenia, schizoaffective disorder, and bipolar disorder with psychosis. Diagnosis was determined using the Structured Clinical Interview for DSM-IV prior to inclusion in the study.
Results: Significant intergroup differences were found for severity ratings of S1, S3, S4, and FRS (p=0.0043, p<2×10-16, p=0.00072, and p=4.4×10-13, respectively) and duration of S1, S3, S4, and overall FRS (p=4.9x 10-6, p<2×10-16, p=3.9×10-9, and p<2×10-16, respectively) between schizophrenia and bipolar with psychosis groups. Significant intergroup differences were also found for severity ratings of S1, S3, S4, and overall FRS (p=0.0063, p<2×10-16, p=0.01570, and p=4.1×10-10, respectively) and duration of S1, S3, S4, and overall FRS (p=5.2×10-6, p<2×10-16, p=2.7×10-7, and p<2×10-16, respectively) between schizoaffective disorder and bipolar with psychosis groups. No significant differences were found between schizophrenia and schizoaffective disorder for any symptom ratings.
Conclusions: Analysis suggests that first-rank symptoms are not exclusively predictive of schizophrenia but effectively differentiate schizophrenia from bipolar disorder with psychosis and schizoaffective disorder from bipolar disorder with psychosis.
Live Zoom Session – April 21st
Courtney Spitzer, BA, Tabinda Khan, BA, Victor Zeng, BS, Gautami Shashidhar, BA, Nicole Varca, BA, Paulo Lizano, MD, PhD, Matcheri Keshavan, MD
Matcheri Keshavan, MD