Diffusion tensor imaging tractography of the fornix and belief confidence in first-episode psychosis

Previous studies have demonstrated that patients with psychosis are more confident in beliefs and judgments compared to healthy participants and psychiatric controls with major depression. A recent study conducted by our research group has provided evidence for hippocampal pathology in association with overconfidence in a first-episode psychosis sample. The fornix is the primary efferent neural pathway of the hippocampus and may also play a role in self-certainty pathophysiology. The current investigation applied diffusion tensor imaging tractography to a first-episode psychosis sample to explore whether integrity of the fornix is associated with self-certainty. High resolution structural magnetic resonance and diffusion tensor images were obtained in 44 people with a first-episode psychosis. Diffusion tensor imaging tractography was used to estimate fractional anisotrophy (FA), a measure of white matter integrity, in the fornix. Confidence in beliefs and judgments was measured with the self-certainty subscale of the Beck Cognitive Insight Scale (BCIS). The analysis showed that self-certainty significantly correlated to FA values in the right fornix but was nonsignificant for the left fornix. The findings indicate anatomical dysconnectivity of the right fornix in correlation with BCIS-rated self-certainty in our first-episode psychosis sample. When considered with our previously published self-certainty-hippocampus result in a first-episode psychosis sample, overlapping with that of this study, the results indicate a concurrence of volumetric reductions in hippocampus and fornix pathology in correlation with self-certainty.