Association of Folate Level in Blood with the Risk of Schizophrenia

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.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).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).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.