White matter microstructure in schizophrenia: effects of disorder, duration and medication

Abstract

Background: Diffusion tensor magnetic resonance imaging studies in schizophrenia to date have been largely inconsistent. This may reflect variation in methodology, and the use of small samples with differing illness duration and medication exposure.

Aims: To determine the extent and location of white matter microstructural changes in schizophrenia, using optimised diffusion tensor imaging in a large patient sample, and to consider the effects of illness duration and medication exposure.

Method: Scans from 76 patients with schizophrenia and 76 matched controls were used to compare fractional anisotropy, a measure of white matter microstructural integrity, between the groups.

Results: We found widespread clusters of reduced fractional anisotropy in patients, affecting most major white matter tracts. These reductions did not correlate with illness duration, and there was no difference between age-matched chronically and briefly medicated patients.

Conclusions: The finding of widespread fractional anisotropy reductions in our larger sample of patients with schizophrenia may explain some of the inconsistent findings of previous, smaller studies.

Fig. 1

Areas of reduced fractional anisotropy in patients with schizophrenia v. controls (the left of the brain is on the right of the slice images).

Fig. 2

Scatter plot of illness duration against mean segmented white-matter fractional anisotropy in patients with schizophrenia.

Fig. 3

White matter voxels where mean fractional anisotropy is lower (a) and higher (b) in patients than in controls (unthresholded comparison).