Serum Level of Growth-Associated Protein 43 Is Associated with First-Episode Schizophrenia Patients without Antipsychotic Drugs Treatment

Nerve growth-associated protein 43 (GAP43) is closely related to neural development, axon regeneration, and synaptic reconstruction and is one of the important markers of neuronal damage. Therefore, in our study, enzyme-linked immunosorbent assay (ELISA) was used to analyze the serum level of GAP43 protein in schizophrenia patients (n = 188), healthy controls (n = 200), and bipolar disorder patients (n = 200). The positive and negative syndrome scale (PANSS) was used to evaluate the mental status of schizophrenia patients, and the Scale of Social Function in Psychosis Inpatients (SSPI) was used to evaluate the social function of schizophrenia patients. According to this study, we found the serum GAP43 level was significantly higher in schizophrenia patients than in bipolar disorder patients, while serum GAP43 levels in bipolar disorder patients were significantly higher than those in control group. When the cut-off value was set as 2.328 ng/mL, the area under the curve (AUC) of serum GAP43 was 0.7795 (95% CI: 0.7431–0.8158) for diagnosis of schizophrenia. The sensitivity and specificity were 92.02% and 65.25%, respectively. However, no correlation between serum GAP43 and the total scores of PANSS scale in schizophrenia patients as well as between serum GAP43 level and SSPI were observed. Therefore, we believe that GAP43 may be a potential diagnostic marker for schizophrenia.