From Speech Illusions to Onset of Psychotic Disorder: Applying Network Analysis to an Experimental Measure of Aberrant Experiences
Authors: Boyette Lindy-Lou , Isvoranu Adela-Maria , Schirmbeck Frederike , Velthorst Eva , Simons Claudia J P , Barrantes-Vidal Neus , Bressan Rodrigo , Kempton Matthew J , Krebs Marie-Odile , McGuire Philip , Nelson Barnaby , Nordentoft Merete , Riecher-Rössler Anita , Ruhrmann Stephan , Rutten Bart P , Sachs Gabriele , Valmaggia Lucia R , van der Gaag Mark , Borsboom Denny , de Haan Lieuwe , van Os Jim ,   EU-GEI High Risk Study, McGuire Philip , Valmaggia Lucia R , Kempton Matthew J , Calem Maria , Tognin Stefania , Modinos Gemma , de Haan Lieuwe , van der Gaag Mark , Velthorst Eva , Kraan Tamar C , van Dam Daniella S , Burger Nadine , Nelson Barnaby , McGorry Patrick , Amminger G Paul , Pantelis Christos , Politis Athena , Goodall Joanne , Riecher-Rössler Anita , Borgwardt Stefan , Studerus Erich , Bressan Rodrigo , Gadelha Ary , Brietzke Elisa , Asevedo Graccielle , Asevedo Elson , Zugman Andre , Barrantes-Vidal Neus , Domínguez-Martínez Tecelli , Cristóbal-Narváez Paula , Kwapil Thomas R , Monsonet Manel , Hinojosa Lídia , Kazes Mathilde , Daban Claire , Bourgin Julie , Gay Olivier , Mam-Lam-Fook Célia , Krebs Marie-Odile , Nordholm Dorte , Randers Lasse , Krakauer Kristine , Glenthøj Louise , Glenthøj Birte , Nordentoft Merete , Ruhrmann Stephan , Gebhard Dominika , Arnhold Julia , Klosterkötter Joachim , Sachs Gabriele , Lasser Iris , Winklbaur Bernadette , Delespaul Philippe A , Rutten Bart P , van Os Jim 
Published: May 2020

Abstract
Aberrant perceptional experiences are a potential early marker of psychosis development. Earlier studies have found experimentally assessed speech illusions to be associated with positive symptoms in patients with psychotic disorders, but findings for attenuated symptoms in individuals without psychotic disorders have been inconsistent. Also, the role of affect is unclear. The aim of this study was to use the network approach to investigate how speech illusions relate to individual symptoms and onset of a psychotic disorder. We estimated a network model based on data from 289 Clinical High-Risk (CHR) subjects, participating in the EU-GEI project. The network structure depicts statistical associations between (affective and all) speech illusions, cross-sectional individual attenuated positive and affective symptoms, and transition to psychotic disorder after conditioning on all other variables in the network. Speech illusions were assessed with the White Noise Task, symptoms with the BPRS and transition during 24-month follow-up with the CAARMS. Affective, not all, speech illusions were found to be directly, albeit weakly, associated with hallucinatory experiences. Hallucinatory experiences, in turn, were associated with delusional ideation. Bizarre behavior was the only symptom in the network steadily predictive of transition. Affective symptoms were highly interrelated, with depression showing the highest overall strength of connections to and predictability by other symptoms. Both speech illusions and transition showed low overall predictability by symptoms. Our findings suggest that experimentally assessed speech illusions are not a mere consequence of psychotic symptoms or disorder, but that their single assessment is likely not useful for assessing transition risk.