Predicting Antipsychotic Discontinuation in Psychosis

Predicting Successful Antipsychotic Discontinuation in the First Episode Psychosis by Using Positron Emission Tomography(PET) withPositron Emission Tomography With 3,4-dihydroxy-6-18-fluoro-l-phenylalanine ([18 Fluorine(F)]DOPA)

The purpose of this study is to determine whether dopamine synthesis capacity by using [18 fluorine(F)]-DOPA PET for patients with schizophrenia in the maintenance phase can predict treatment discontinuation.

There are two groups: the healthy control group (n=12) and the patient group (n=26). The patient group recruits subjects diagnosed with first episode psychosis which occurred within 2 years and having been treated with antipsychotics for 1 year. Participants will complete clinical scales and undergo PET scans. Subjects in the patient group will receive a reduced intake of antipsychotics by 25% after each week of the four-week period in which they will also undergo PET imaging at the baseline, 7 week, and 8 week marks to detect the correlation between the capacity of presynaptic dopamine and relapse in the patients discontinuing treatment.

Inclusion Criteria:

1. Patient group

1. Patients who met DSM-IV criteria for schizophrenia, schizoaffective disorder, and schizophreniform disorder
2. patients diagnosed with first episode psychosis which occurred within 2 years and having been treated with antipsychotics for at least 1 year.
3. Patients who have maintained in the stable state for 3 months without medication change at the baseline.

2. Healthy control group

• Healthy controls has no Axis I disorder and do not report any past event of neurological or psychiatric illness assessed by the Structured Clinical Interview for DSM Disorders

Exclusion Criteria:

1. Participants should not have any neurological illness such as head trauma, seizure and meningitis.
2. Participants should not be diagnosed as Mental retardation(IQ<70)
3. Participants should not have severe personality disorder, substance abuse or dependence (except for nicotine abuse and dependence) and severe medical conditions.