Metformin Treatment on Cognitive Impairment of Schizophrenia

Inclusion Criteria: Male and female with aged 18 to 50 years, who meet the Diagnostic and Statistical Manual (DSM-5) diagnostic criteria for schizophrenia; Duration of illness less than 15 years with current symptoms in a stable condition; Participants must be receiving stable treatment with standard-of-care medications, with a maximum allowance of two antipsychotic medications. If additional anticholinergic agents are required for the management of extrapyramidal symptoms, they should be prescribed at low dosages; Have great compliance on medication and follow-up； Meet one of the diagnostic criteria for metabolic syndrome: 1)abdominal obesity (i.e. central obesity): waist circumference for male≥90 cm, for female ≥85 cm; 2)fasting blood glucose ≥110 mg/dl (6.1 mmol/l) and/or plasma glucose ≥140 mg/dl (7.8 mmol/l) after glucose load; 3)at fasting state, triglyceride ≥1.7 mmol/l; 4)at fasting state, HDL-C <1.04 mmol/L. Signed the study consent for participation. Exclusion Criteria: Having history of substance dependence or abuse or whose symptoms are caused by the other diagnosable mental disorders; Having history of traumatic brain injury, seizures or other known neurological or organic diseases of the central nervous system; Taking antidepressants, stimulants, mood stabilizer or accepts electricity shock treatment; Having current suicidal or homicidal thoughts or any safety concern by research staff that cannot be manage in an inpatient setting; Taking dementia related drugs, minocycline, and other drugs that could affect cognitive function. The routine blood tests showing significant abnormal renal, liver function or other somatic disease. Pregnant or lactating women.