A Study to Compare Two Different Brain Imaging Techniques in Healthy Volunteers and in Schizophrenic Patients

Inclusion criteria: * Not pregnant or becoming pregnant during the study. * No abnormality in clinical examination, clinical laboratory test or ECG. * Not taking drugs * Patients with schizophrenia, schizophreniform disorder or schizoaffective disorders. * Patients with at least 1 month antipsychotic monotherapy with either risperidone, olanzapine or clozapine. * Healthy volunteers with no neurological or psychiatric illness. Exclusion criteria: * Have received other antipsychotic during the last month or neuroleptics during the last year. * If you have taken part in investigations you should not receive a radiation dose of more than 10 mSv over any 3 year period. * History of bleeding disorder or are taking medication that affects blood clotting * History of substance dependence (except nicotine) * Claustrophobia * Gross head deformity. * Unable to lie still in the PET or SPECT camera for 1 hour and a half. * The presence of a cardiac pacemaker or other electronic device or ferromagnetic metal foreign bodies.