Comparison of Serum Folate between Schizophrenic Patients and Healthy Controls in Chinese Han Adult Population: A Systematic Review and Meta-Analysis

Aim and Objective: To assess the relationship between serum folate and schizophrenia (SZ) risk in the Chinese Han adult population in different papers, a systematic review and metaanalysis were conducted. Materials and Methods: We searched for this meta-analysis on three English databases (PubMed, Embase, and Web of science) and four Chinese databases (CNKI, SinoMed, Wanfang, and CQVIP) on March 27, 2021. Inclusion criteria: studies provided folate levels in serum of cases and controls as mean and standard deviation. Exclusion criteria: subjects were not Chinese Han adult population. The Newcastle-Ottawa Scale score was used to assess the risk of bias in the included studies. Standard mean difference (SMD) was used to measure the difference between SZ patients and healthy controls. Subgroup analyses by measurement time, duration, and age were performed, respectively. Results: This meta-analysis included 19 publications involving 1571 SZ cases and 1283 healthy controls. In total studies, the pooled result showed that SZ patients had decreased serum folate levels compared with healthy controls (SMD [95%CI] = -1.37[-1.83,-0.90], PSMD<0.001), and in most of the subgroups, the associations reached decreased significantly; while in the subgroup of drugs use, the association was not reached significantly. Conclusion: Dose-response analysis and subgroup analyses by gender were not performed due to the lack of data. Folate deficiency is associated with the patients, and antipsychotic drugs might have positive effects on improving serum folate levels in Chinese Han adult SZ.