Personality, psychosis, and connectivity: Neuroimaging endophenotypes in the psychotic spectrum

Abstract

The link between diagnoses of psychotic disorders and altered structural and functional brain connectivity is well established, yet little is known about the degree to which similar neural features predict traits linked to psychosis-proneness in the general population. Moreover, intelligence is too rarely considered as a covariate in neural endophenotype studies, despite its known protective role against psychopathology in general and its associations with broad aspects of neural structure and function. To determine whether psychosis-linked personality traits are linearly associated with putative psychosis endophenotypes, this dissertation examines white matter and functional connectivity correlates of Psychoticism, Absorption, and Openness to Experience in a large community sample, covarying for sex, age, and IQ. Findings support the hypothesis that the white matter correlates of the shared variance of these traits overlap substantially with the frontal lobe white matter connectivity patterns characteristic of psychotic spectrum disorders. Positive schizotypy did predict connectivity in hypothesized functional networks, but also appears positively associated with average coherence across all intrinsic networks. These findings provide biological support for the notion that liability to psychosis is distributed throughout the population, is evident in measureable neural features, and manifests as normal personality variation at subclinical levels.