Review and meta-analysis of usage of ginkgo as an adjunct therapy in chronic schizophrenia

Abstract

This study aimed to review the roles of antioxidants in the pathophysiology of schizophrenia, whether the properties of ginkgo can ameliorate symptoms of this illness, and evaluate available literature to test this assumption. This review is based upon published works on antioxidants and ginkgo. A primary electronic search for meta-analysis on the usage of ginkgo or its derived products in schizophrenia was conducted using Pubmed, Cochrane Library, EMBASE, CINAHL, PsycINFO and AMED. Inclusion criteria were: criteria-based diagnosis of schizophrenia, randomized case assignment, use of ginkgo as an add-on therapy, and assessment using standardized rating scales to measure the state of psychopathology for negative and total symptoms of schizophrenia. Additionally, a detailed review was undertaken to investigate if antioxidants are involved in development of psychotic symptoms in schizophrenia. The six studies that fulfilled the selection criteria were constituted of 466 cases on ginkgo and 362 cases on placebo. They all used the Scale for the Assessment of Negative Symptoms (SANS) to measure negative symptoms, and the Scale for the Assessment of Positive Symptoms (SAPS) or the Brief Psychiatric Rating Scale (BPRS) to measure total symptoms. Difference between ginkgo and control groups from their pre- and post-trial scores and its pooled standard deviation were used to compute standardized mean difference (SMD). Ginkgo as an add-on therapy to antipsychotic medication produced statistically significant moderate improvement (SMD=-0.50) in total and negative symptoms of chronic schizophrenia. Ginkgo as add-on therapy ameliorates the symptoms of chronic schizophrenia. The role of antioxidants in pathogenesis of schizophrenia has also been explored.