1. patients: meets dsm-iv criteria for schizophrenia, any type, or schizoaffective disorder;

2. aged 18 to 60 years;

3. able to give informed consent;

4. no medication changes for 2 weeks prior to and during the period of study; 5. patients: currently taking olanzapine, risperidone, haloperidol or another typical antipsychotic.

1. controls: axis i psychiatric disorder criteria met except for substance use disorders as below;

2. meets dsm-iv criteria for the diagnoses of substance abuse or dependence within the past six months;

3. involuntary legal status (as per missouri law);

4. the presence of any serious medical disorder that may (as confirmed by peer-reviewed literature) confound the assessment of symptoms, relevant biologic measures or diagnosis; the following conditions are currently identified: insulin- or non-insulin-dependent diabetes mellitus; any intra-abdominal or intrathoracic surgery or limb amputation within the prior 6 months; any diagnosed cardiac condition causing documented hemodynamic compromise; any diagnosed respiratory condition causing documented or clinically recognized hypoxia; pregnancy or high dose estrogens, fever, narcotic therapy, acute sedative hypnotic withdrawal, corticosteroid or spironolactone therapy, dehydration, epilepsy, endocrine disease, high-dose benzodiazepine therapy (> 25 mg/day of diazepam), or any medical condition known to interfere with glucose utilization;

5. meets dsm-iv criteria for mental retardation (mild or worse).