Use Huperzine-A, a herbal supplement normally used for treatment of Alzheimer's disease, to potentially improve cognitive dysfunction (memory problems) and functional capacity (ability to perform common daily tasks such as cooking, bathing, telephone, shopping) in people with schizophrenia.

HupA, an alkaloid initially identified from the Chinese herbal medicine Huperia serrata, is a potent reversible acetyl cholinesterase (AChE) inhibitor with additional unique properties including NMDA-receptor antagonist properties, neuroprotective and antioxidant effects. In animal studies, HupA was shown to possess greater inhibitory, longer-lasting, and more selective effects on AChE activity than donepezil. In clinical studies HupA improved memory, mood, and activities of daily living in patients with Alzheimer's dementia. Adverse effects have been reported at a very low rate in all the clinical trials, and are mainly cholinergic, such as dizziness, nausea, gastrointestinal symptoms, headaches and depressed heart rate. Thus, HupA is an attractive option which may have beneficial effects not only on cognitive but also functional domains of schizophrenia.

Inclusion Criteria:

1. age 19-59
2. diagnosis of schizophrenia by MINI
3. cognition score 1 standard deviation below published norms in controls
4. clinically stable for 12 weeks i.e. on the same antipsychotic(s) for 8 weeks and stable dose for at least 4 weeks
5. have no more than moderate severity rating on hallucinations, delusions formal thought disorder (BPRS), negative symptoms (PANSS_N)
6. minimal EPS (Simpson-Angus <6)
7. minimal depression (Calgary <10)
8. stable dose of other psychotropics (2 months)
9. not pregnant.

Exclusion Criteria:

1. history of active peptic ulcer disease within 1 year of screening
2. clinically significant cardiac arrhythmia
3. resting pulse less than 50
4. active cancer (skin tumors other than melanoma are not excluded)
5. history of clinically significant stroke
6. current evidence or history in the past 2 years of epilepsy, focal brain lesion
7. start of cholinesterase inhibitors/ cognitive enhancers (galantamine, rivastigmine, donepezil, vitamin E and memantine) within 2 months of screening, 8. use of medications with significant central nervous system anticholinergic activity within 2 months of screening.