This study will determine the effectiveness of artemisinin plus risperidone in improving symptoms and cognitive disturbances and in Chinese people with schizophrenia. The study addresses the Toxoplasma infection hypothesis of schizophrenia.

Evidences of high levels of Toxoplasma gondii antibodies in the serum and the cerebrospinal fluid (CSF) of individuals with schizophrenia have suggested that this organism might be involved in the etiopathogenesis of schizophrenia. The investigators hypothesize that antimicrobial therapy by using an add-on agent together with a well-proven neuroleptic may have favorable effects on a subgroup of schizophrenic patients.

Inclusion Criteria:

• Currently resides in Beijing, China
• Diagnosis of schizophrenia or schizophreniform disorder
• Duration of symptoms is no longer than 60 months
• No history of treatment with antipsychotic medication or, if previously treated, a total lifetime usage of less than 14 days
• Current psychotic symptoms are of moderate severity or greater as measured by one of the five psychotic items in the Brief Psychiatric Rating Scale (BPRS)

Exclusion Criteria:

• DSM-IV Axis I diagnosis other than schizophrenia or schizophreniform psychosis
• Documented disease of the central nervous system that might interfere with the trial assessments (e.g., stroke, tumor, Parkinson's disease, Huntington's disease, seizure disorder, history of brain trauma resulting in significant impairment, chronic infection)
• Acute, unstable, and/or significant and untreated medical illness (e.g., infection, unstable diabetes, uncontrolled hypertension)
• A clinically significant echocardiogram (ECG) abnormality in the opinion of the investigator
• Pregnant or breastfeeding
• Use of prohibited concomitant therapy
• History of severe allergy or hypersensitivity
• Dependence on alcohol or illegal drugs
• Use of any of the following medications during the trial: antipsychotic medications other than risperidone; psychostimulants; or antidepressants