The purpose of this study is to determine whether minocycline are effective in the treatment of negative and cognitive symptoms in schizophrenia.

Immune-related disorders have been hypothesized as etiological factors in schizophrenia.Minocycline is a second-generation tetracycline that exerts anti-inflammatory and antimicrobial effects while having a distinct neuroprotective profile.This study was performed as a double-blind, placebocontrolled,randomized evaluation of Second generation antipsychotics(SGA) and minocycline versus SGA and placebo.

Inclusion Criteria:

• male and female,were aged 18-40 years
• were currently diagnosed with DSM-IV schizophrenia
• were able to comprehend the cognition test
• patients or guardian signed informed consent,were able to comprehend the procedure and aims of the study,agreed to join the study
• patient's current antipsychotic medication regimen must be stable
• must be in a stable living arrangement

Exclusion Criteria:

• had ever been hypersensitivity to minocycline or tetracycline;
• had acute,unstable,significant,or untreated medical illness besides schizophrenia
• were pregnant or breast-feeding;
• had a DSM-IV diagnosis of substance abuse or dependency;
• had a tendency to suicide or Violence,self-harm;
• had taken immunosuppressive agents in the preceding 3 months before study entry;
• had influenza or fever in the preceding 2 weeks before study entry;
• had a DSM-IV diagnosis of emotional psychosis,Mental retardation,etc.
• has suicidal attempts or ideation or violent behavior within the last 12 months
• patient has mental retardation or severe organic brain syndromes
• treatment with Electroconvulsive Therapy (ECT) within 6 months prior to screening