Elevated prolactin levels in patients with schizophrenia: mechanisms and related adverse effects.

The neurologic processes involved in schizophrenia are complex and diverse and the mechanisms through which antipsychotic agents exert their effects have been only partly elucidated. Hyperprolactinemia is a common side effect of treatment with many antipsychotics and is particularly associated with conventional ('typical') agents as well as the atypical antipsychotic risperidone. In contrast, other atypical agents introduced over the last decade do not elevate prolactin levels. This article discusses the regulatory mechanisms involved in prolactin secretion, the physiologic role of prolactin, and the etiology of hyperprolactinemia. Elevated prolactin levels may play important roles, both direct and indirect, in various pathologic states, including breast cancer, osteoporosis, cardiovascular disorders, and sexual disturbances. Antipsychotic-induced hyperprolactinemia may be associated with similar clinical manifestations; these are examined with particular reference to patients with schizophrenia.