White Matter Integrity and Verbal Memory Following a First Episode of Psychosis: A Longitudinal Study

Psychotic disorders are a class of heterogeneous disorders for which there is evidence of numerous structural and functional brain abnormalities. One proposed neural marker for psychosis is a disruption in white matter, the structural architecture for connectivity throughout the brain. The role of white matter integrity, often measured via Fractional Anisotropy (FA), has played a controversial role in individuals with a first episode of psychosis (FEP), with some finding widespread white matter deficits and others finding no significant differences between FEP and controls. Similarly, some FEP studies have observed that higher FA is associated with better verbal memory, but others failed to find such an association. Studying the early stages of psychosis represents a promising avenue to overcome previous confounding factors and characterize the disease in its early clinical stages.Eighty individuals with a FEP were recruited from a specialized early intervention program for psychosis alongside 55 non-clinical controls from the community matched for age and sex. Both groups were followed and scanned 4 times: at baseline (within 3 months after program entry), 6 months, 12 months, and 18 months. TBSS were used on 3.0 Tesla diffusion-weighted images to extract fractional anisotropy values for white matter regions of interest in accordance with the JHU white-matter tractography atlas. The analysis revealed no significant main effect of group or time, and no significant associations between FA and verbal memory. Fractional anisotropy is still within normal ranges 18 months after the onset of FEP with no substantial differences between groups or over time.Keywords: Diffusion, fractional anisotropy, schizophrenia spectrum, cognition, neuroimaging