False-positive dexamethasone suppression test results related to antipsychotic drug withdrawal: case report.

A nonmelancholic schizophrenic patient showed a positive dexamethasone suppression test (DST) 3 days after antipsychotic drug withdrawal. The patient was then put on a stable dose of the antipsychotic and a repeat DST showed normal suppression. The drug was again stopped, and 3 days later a DST was positive. This indicates that antipsychotic withdrawal may lead to false-positive DST results. The theoretical implications and clinical relevance of this finding are discussed.