Differential diagnosis of delusional symptoms in schizophrenia: Brain tractography data

Abstract

Delusion is an extreme distortion of cognitive processes evaluating reward and prediction, where the damage in structural connectivity between several brain regions responsible for actualization of acquired socioemotional experience and adequate analysis of what is happening serve as a pathomorphological substrate. Referring to the assumption on various neurophysiological developmental mechanisms of two types of delusion, i.e. persecutory and fantastic, we hypothesized that the neural pathways or white matter tracts significantly differ between patients with one of the two types of delusions. Materials and methods40 patients suffering from schizophrenia were examined, 25 of them diagnosed with fantastic/paraphrenic delusions and 15 of them having persecutory/interpretative delusions. The control group comprised 42 healthy age- and sex-matched volunteers. Diffusion MR tractography of the brain was performed using 3 T MRI Magnetom Verio, Siemens. Resultsstatistical decrease in white matter fibers connecting right frontal regions with left motor cortex and certain cerebellar zones was identified in patients with interpretative delusions compared to healthy individuals. Elevated number of white matter fibers was found between the occipital regions and calcarine sulcus of the left hemisphere, and between medial occipitotemporal sulcus of the right hemisphere and right fusiform gyrus when comparing the tracts of patients with fantastic delusions and healthy controls. Conclusionsinterpretative delusions are associated with impaired connectivity in the brain regions responsible for adequate monitoring of current reality, whereas fantastic delusions are accompanied by altered connectivity of regions controlling multimodal sensory integration of signals from various analyzers based on long-term memory attributions.