Temporal characteristics of tract-specific anisotropy abnormalities in schizophrenia.

White matter abnormalities have been detected using diffusion tensor imaging in a variety of locations in the brains of patients with schizophrenia. Studies that included first-episode patients report less severe or no abnormalities but more pronounced deficits in chronic patients. Here, we investigated these abnormalities in a very large group of patients with schizophrenia who had both large ranges in age and in duration of illness. A highly reproducible diffusion tensor imaging tractography technique was used to quantify the fractional anisotropy of the genu and splenium of the corpus callosum as well as the bilateral pyramidal tracts. We found a decline in fractional anisotropy that correlated with the duration of illness in the genu and splenium of the corpus callosum but not in the pyramidal tracts. The findings suggest that there are white matter tract-specific degenerative mechanisms that may be present at the point of illness onset and may progress throughout the illness.