Metformin Treatment on Cognitive Impairment of Schizophrenia

Participants assigned to the metformin group will receive 500mg metformin three times daily (tid) for 24 weeks. The initial dose will be 500 mg orally in the evening for the first two days, followed by an increase to 500mg twice a day for the subsequent two days. By day 5, the dosage will be further increased to 500mg tid. The highest tolerated dosage will be maintained for participants who could not tolerate the maximum dosage.

Parallel-dose adjustments will be made for the placebo group to maintain consistency in dosing between the two groups.

Schizophrenic participants who don't meet any of the diagnostic criteria for metabolic syndrome will only accept baseline evaluations.

Apart from psychiatry scales(Hamilton Depression Scale, Young Mania Rating Scale and Self-reporting Inventory-90), other assessments for the healthy subjects are the same as the baseline for sczhiophrenic participants.