Aim and Objective: The aim of this study was to evaluate the association between folate level and the risk of schizophrenia and to identify possible biomarker for schizophrenia.Materials and Methods: Data about folate were extracted from 16 high quality studies. The association of folate level in blood and schizophrenia was evaluated using standardized mean difference (SMD) and 95% confidence interval (CI). Results: Totally 1183 (52.1%) cases and 1089 (47.9%) controls were included in the current metaanalysis. Folate level in schizophrenia patients was significantly lower than that in healthy controls (SMD= −0.65; 95% CI: [−0.86, −0.45]; P <0.00001). Subgroup analysis demonstrated that the decreased folate level was found in both Asian and European patients (SMD=−0.86, P<0.00001; SMD=−0.44, P<0.00001, respectively), while there were no significant differences in patients from other areas (P>0.05). Sensitivity analysis confirmed that these results were stable and reliable, no publication bias existed in our meta-analysis based on Egger's and Begg's tests (P=0.48 and 0.30, respectively). Conclusion: These results suggest that decreased folate may be a risk factor for schizophrenia. More epidemiological and biochemistry studies are required to describe how folate or folate supplementation play roles in the progress of schizophrenia.
Keywords: Folate, schizophrenia, meta-analysis, case-control study, folic acid, neurodevelopmental disorders.