White matter integrity and verbal memory following a first episode of psychosis: A longitudinal study

Psychotic disorders are heterogeneous disorders for which there is evidence of structural and functional brain abnormalities. 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). 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. Tract-Based Spatial Statistics (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 John Hopkins University white-matter tractography atlas. The analysis revealed no significant main effect of group or time, and no significant associations between FA and verbal memory. Overall, differences in FA are small early in the course of illness and longer follow-up periods may be required to identify possible changes during a critical intervention window.