Why do not all high schizotypes develop schizophrenia? Protective factors in people with high risk for schizophrenia using machine learning methods
Human Cognitive and Systems Neuroscience
Personality Psychology, Clinical and Medical Psychology, Methodology
Final Report Abstract
Schizophrenia is a severe mental disorder that is characterised by positive symptoms, negative symptoms and thought disorder as well as cognitive dysfunction. An important realisation in schizophrenia research has been that the disorder is not, despite its reliable identification with clinical diagnostic tools, a condition with discrete boundaries. Instead, schizophrenia has frequently been conceptualised as being dimensional, both with regards to other clinical disorders and with inter-individual variation in the subclinical range. Within schizophrenia research, the most widely studied subclinical spectrum phenotype is schizotypy, a constellation of personality traits that are thought to harbour risk for schizophrenia. Schizotypal traits are often grouped into positive, negative and disorganised dimensions, resembling the symptom structure of schizophrenia. Individuals with high levels of schizotypy display schizophrenia-like but milder patterns of behavioural, cognitive, oculomotor and brain structural and functional aberrations. This converging evidence supports arguments for the dimensionality of schizophrenia and schizotypy. Whilst numerous studies have thus provided evidence in favour of similarities or continuities between schizophrenia and schizotypy, very little research has been devoted to identifying dissimilarities or discontinuities. This project aims to do so by directly comparing data from recent onset schizophrenia spectrum patients, individuals with high levels of negative or positive schizotypy, and healthy controls. The study was carried out in two centres (Bonn, Munich). Participants underwent functional magnetic resonance imaging (fMRI) at 3T while they performed oculomotor tasks known to tap sensitivity for schizophrenia and schizotypy, viz. antisaccades and smooth pursuit eye movements. At level of oculomotor performance, our results broadly replicate the well described patterns of impairment in antisaccade and smooth pursuit eye movements in schizophrenia. Classification analysis of patients and controls was significant on the basis antisaccade, but not smooth pursuit data. With regards to fMRI data, classification of patients and controls was significant on the basis of smooth pursuit, but not antisaccade data. Individuals with high levels of positive or negative schizotypy were generally in between patients and controls in oculomotor and fMRI data, but were fond to be more similar to controls than patients. Overall, this project represents the first study to apply classification analysis to fMRI and oculomotor data in schizophrenia spectrum patients and schizotypal individuals. The project advances the literature by providing much needed, direct comparisons between schizotypal individuals and not only healthy controls but also schizophrenia spectrum patients. The findings will be an important basis for further investigations of the question of continuities and discontinuities across different schizophrenia spectrum phenotypes and the search for compensatory or protective influences in individuals with high levels of schizotypal personality traits.
Publications
- (2020). Mechanisms of smooth pursuit eye movements in schizotypy. Cortex, 125, 190-202
Faiola E, Meyhöfer I, Ettinger U
(See online at https://doi.org/10.1016/j.cortex.2019.12.008)
