LAUSR

Abstract Background: Studies using proton magnetic resonance spectroscopy (1H-MRS) have reported altered neurometabolite levels in patients with schizophrenia. However, results are inconsistent and confounded by the influence of antipsychotic (AP) administration. Thus, the aim of the present study was to examine neurometabolite levels in AP-naive/free patients with schizophrenia through a meta-analysis. Methods: A literature search was conducted using Embase, Medline, and PsycINFO to identify studies that compared neurometabolite levels in AP-naive/free patients with schizophrenia to healthy controls (last search: August 2016). Eight neurometabolites (glutamate, glutamine, glutamate + glutamine, N-acetylaspartate [NAA], choline, creatine, myo-inositol, and γ-aminobutyric acid) and 7 regions of interest (ROI; medial prefrontal cortex, dorsolateral prefrontal cortex, frontal white matter, occipital lobe, basal ganglia, hippocampus/medial temporal lobe, and thalamus) were examined. Standardized mean differences (SMDs) were calculated to assess neurometabolite-level differences between groups. Results: Twenty-two studies (N = 1142) were included in the analysis. The results showed lower thalamic NAA levels in the patient group (SMD = −0.56, P = .0005). No differences were identified for other neurometabolites. Conclusion: This study extends previously reported findings demonstrating a decrease of NAA levels in patients with chronic schizophrenia. On the other hand, previously reported alterations of glutamatergic neurometabolite levels were not replicated. Further studies are required to detect the influence of AP on these neurometabolites levels.