LENA PALANIYAPPAN1, Tushar Das1, Fabienne Harrisberger2, Undine E. Lang2, Anita Riecher-Rössler3, André Schmidt3, Stefan Borgwardt3; 1University of Western Ontario, 2Psychiatric University Clinics Basel, 3University of Basel
In psychiatry, when symptoms “come together” we call the resulting construct as a diagnosis. We infer a disease process binding varied symptoms together, enabling their co-occurrence. We then use syndromic labels to describe this construct (e.g. schizophrenia, at-risk mental state). But how does the intrinsic relationship among symptoms change with transition from at-risk states to first episode psychosis? We recruited 63 subjects with at-risk mental state [PACE criteria] but no transition (ARMS-NT), 16 that later developed psychosis (ARMS-T) and 38 drug-naïve patients with first-episode psychosis (FEP) from Basel, Switzerland. Symptoms were measured using Brief Psychiatric Rating Scale. We estimated each individual’s contribution to the relatedness found among symptoms using a jack-knife bias estimation procedure. Higher values meant greater relationship between two given symptoms in that subject, relative to the rest of the group. None of the 24 individual symptoms of BPRS significantly differentiated ARMS-NT from ARMS-T, though the intrinsic organisation revealed significantly increased clustering (Hedges’s g = 0.60, p<0.05) and modularity (g = 0.81, p<0.01) in ARMS-T compared to ARMS-NT. There were no differences between ARMS-T and FEP groups. In both ARMS-T and FEP groups, anxiety was the most central symptom. In addition to anxiety, the FEP group also had unusual thought content emerging as a central feature. Risk of transition to psychosis relates to the consolidation of relationship among symptoms rather than the severity of symptoms per se. First episode of psychosis could be thought of as a state of high modular clustering among otherwise sparsely connected symptoms.
