Age effects on diffusion tensor magnetic resonance imaging tractography measures of frontal cortex connections in schizophrenia

Abstract

Diffusion tensor magnetic resonance imaging (DT‐MRI) has previously been used to investigate white matter tracts in schizophrenia, with inconsistent results. The aim of the study was to use a novel method for tract‐specific measurements of fronto‐temporal fasciculi in early‐onset schizophrenia. We hypothesized that by making tract‐specific measurements, clear diffusion abnormalities would be revealed in specific fasciculi in schizophrenia. Measurements of diffusion anisotropy and mean diffusivity were localized within fronto‐temporal fasciculi by forming 3‐D reconstructions of the cingulum, uncinate, superior longitudinal, and inferior fronto‐occipital fasciculi using diffusion tensor tractography. We were limited in our ability to test our hypothesis by the important and surprising finding that age affected DT‐MRI‐based measures in schizophrenia patients in a different way from comparison subjects, most notably in the left superior longitudinal fasciculus. The youngest schizophrenia patients that we studied had lower diffusion anisotropy than age‐matched comparison subjects, but this difference diminished with increasing age. The main conclusion of this study was that direct comparisons of absolute DT‐MRI‐based measures between individuals with schizophrenia and comparison subjects may be problematic and misleading because of underlying age‐related differences in brain maturation between groups. Hum Brain Mapp, 2005.