Introduction: Schizophrenia is a brain disorder classified as a psychosis, which may result in some combination of hallucinations, delusions, and extremely disordered thinking and behavior that impairs daily functioning, and can be disabling. According to WHO, Schizophrenia affects approximately 24 million people or 1 in 300 people (0.32%) worldwide. This rate is 1 in 222 people (0.45%) among adults. Onset is most often during late adolescence and the twenties, and onset tends to happen earlier among men than among women. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function. Researches show that deletions or duplications of genetic material in any of several chromosomes, which can affect multiple genes, are also thought to increase schizophrenia risk. An operant number of studies have reported associations between two polymorphisms of Brain-derived neurotropic factor gene (BDNF) and Schizophrenia. This study reports the effect of these polymorphisms on Schizophrenia using meta-analysis method.
Methods: To conduct electronic searches, PubMed was used. For prospective investigations, the keywords "Schizophrenia" and "BDNF gene" or "Brain Derived Neurotrophic Factor gene" as well as "meta" were searched extensively in the electronic literature. We estimated the pooled effect sizes (ORs) and 95% confidence intervals (CIs) for these two polymorphisms (rs6265 (Val66Met) and rs2030324 (C270T) in the "cases" and "controls" groups.
Results: effect model, nine studies totaling 66934 participants—29843 cases and 37091 controls—were included in this meta-analysis. The results showed that these polymorphisms significantly influence schizophrenia, and the pooled OR is 1.01 with a 95% confidence interval of 0.97 to 1.05 and a p-value of less than 0.00, indicating that the test was statistically significant. When it comes to understanding heterogeneity, research become less variable and heterogeneous when I2 is reduced. I2 = 0.00% and H2 = 1.00 in this analysis show that there is no degree of study heterogeneity.
Conclusion: Overall, these findings provide compelling evidence that refutes the null hypothesis. (The null hypothesis is a typical statistical theory which suggests that no statistical relationship and significance exists in a set of given single observed variations, between two sets of observed data and measured phenomena.)