<p>Dysconnectivity in the corticostriatal pathway, which is central to psychosis pathophysiology, is also known to be present in individuals at clinical high risk for psychosis (CHR-P). Considering that the corticostriatal pathway actively matures until adulthood and that neuroanatomical maturation is suggested to be related to functional outcomes in individuals at CHR-P, longitudinal studies on the corticostriatal structural pathway in individuals at CHR-P are warranted. To characterize the longitudinal trajectory of corticostriatal structural connectivity, diffusion-weighted images were collected from 23 individuals at CHR-P and 20 healthy controls (HCs) at baseline and at a 2-year follow-up visit. Probabilistic tractography was performed to segment the pathways between seven cortical regions and the striatum. The relative connectivity between each cortical region and associated striatal subregion was calculated. The CHR-P group was divided into subgroups according to the functional outcome of the modified Global Assessment of Functioning score at follow-up. A significant group‒time interaction between the left orbitofrontal cortex and its associated striatal subregion was found, with a negative slope in the CHR-P group and positive slope in the HC group. In the left orbitofrontal corticostriatal relative connectivity, the group‒time interaction between HCs and individuals at CHR-P with poor functional outcomes at follow-up was statistically significant, whereas that between HCs and individuals at CHR-P with good functional outcomes at follow-up was not. These findings indicate abnormal white matter maturation of the orbitofrontal corticostriatal pathway in individuals at CHR-P. Abnormal neuroanatomical maturation of the orbitofrontal corticostriatal pathway may reflect prognosis for functional outcomes in these individuals.</p>