The effects of clozapine and high-dose olanzapine on brain function in treatment-resistant schizophrenia: a case...

Although demonstrating superior efficacy in people with treatment-resistant schizophrenia, clozapine may cause serious side effects, requires blood monitoring and is costly to administer. Olanzapine is similar to clozapine in molecular structure and pharmacologic action but has not demonstrated as robust results as clozapine at routine doses (10-25 mg). Here we present a case study measuring blood flow by positron emission tomography (PET) imaging for a patient treated sequentially with a high dose of olanzapine (50 mg/day) followed by clozapine each for 8 weeks in a double-blind design. During a task, clozapine produced more brain activation patterns than during treatment with olanzapine or during the drug free condition (2 week washout). Clozapine resulted in recruitment of frontal, parietal and cingulate regions that did not appear to be active during olanzapine in this 44 year old right handed male. Additionally, a more robust decrease in symptoms was noted on the Brief Psychiatric Rating Scale (BPRS) score than with olanzapine treatment. These findings suggest that high doses of olanzapine do not produce similar brain activation patterns as clozapine in people with treatment-resistant schizophrenia.