Diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy (H-1 MRS) in schizophrenic subjects and normal controls

Several proton magnetic resonance spectroscopy(H-1 MRS) studies in schizoph renia have found reduced N-acetyl aspartate (NAA) concentrations in pre-fro ntal and temporal regions of the brain. Reductions in NAA may reflect abnor malities of neuronal structure (e.g, reduced neuronal density or viability) or abnormalities of neuronal function. Diffusion tensor imaging (DTI) meas ures diffusion anisotropy, an indicator of the structural integrity of a ne uronal tract. Both techniques were used to examine the anatomical basis of pre-frontal dysfunction in schizophrenia. Ten patients with DSM-IV schizoph renia were compared with 10 healthy controls. H-1 MRS and DTI were performe d on a clinical MR system and analysed with a region of interest approach. NAA concentrations and diffusion anisotropy were measured in the same pre-f rontal white matter region. Diffusion anisotropy was also measured in a con trol region (occipital white matter). H-1 MRS revealed non-significant but consistently reduced NAA concentrations (by 10-15%) in the pre-frontal whit e matter in schizophrenic subjects. Diffusion anisotropy measures revealed no such differences between schizophrenics and controls. It is concluded th at the abnormalities of 'connectivity' reported in brain-imaging studies of schizophrenia may not be attributable to structural abnormalities of white matter and that reduced NAA in the pre-frontal white matter may reflect ab normal function of structurally intact neurons. (C) 2001 Elsevier Science I reland Ltd. All rights reserved.