Metabolic alterations associated with schizophrenia: a critical evaluation of proton magnetic resonance spectroscopy studies

By reviewing the existing H-1-magnetic resonance spectroscopy literature in schizophrenia, the relationship of different sample characteristics and applied methodologies with metabolite alterations is explored. Furthermore, we emphasize common pitfalls and discrepancies in the methodological framework of the reviewed studies that introduce unwanted variation in findings and complicate the comparison of studies. A total of 92 studies were reviewed. Articles were retrieved by searching the Pubmed database. Care was taken to note down reliability and validity measures of each included study. Despite many methodological differences and shortcomings, progressive NAA reductions could be seen in several brain regions implicated in the pathogenesis of schizophrenia. In terms of treatment effects, cross-sectional evidence implicates a normalizing role for atypical antipsychotic medication; however, longitudinal studies remain inconclusive on this issue. Choline, creatine, and myo-inositol levels remain largely unchanged and a time-dependent role of glutamate finds confirmation in several spectroscopy studies. Other findings are less consistent and need further replication. Most studies lack power and methodological precision. Future studies should aim for standardization and for more distinguished study populations to gain more valid and reliable findings.