Connectivity Abnormalities in Emerging Psychosis

With the advent of modern neuroimaging techniques it was possible to improve our understanding of the potential pathogenetic mechanisms of psychosis. Using functional magnetic resonance imaging and diffusion tensor imaging, numerous studies have elucidated that the core hallmark of psychosis may be abnormal connectivity, although it still remains unclear which regions are most affected. A critical point is that brain connectivity abnormalities, whether structural or functional, are already evident in the psychosis high-risk state and further develop along the psychosis continuum. This suggests that the assessment of the brain connectivity pattern with neuroimaging approaches may permit the detection of the early phases of the illness and may also allow predictions of the course of the disease. In the present chapter, we present an overview of neuroimaging findings of abnormal structural and functional connectivity in subjects at high risk for psychosis. We first report structural connectivity findings derived from diffusion tensor imaging studies, which may serve as a base for the later presented changes in functional and effective connectivity findings obtained from functional magnetic resonance imaging during tasks and resting state. In the last part of this chapter, we also discuss some potential avenues in this field to get one step closer towards a network connectivity-driven classification of the psychosis high-risk state, which may also predict the onset of psychosis.