Neuroendocrine findings in the schizophrenias.

A host of abnormalities have been found in responses to neuroendocrine challenges in the schizophrenias. Some, such as dexamethasone suppression, may be associated with pharmacokinetic differences in the handling of agonists or may represent a contamination of a schizophrenic population by patients with affective disorders. Other abnormalities, such as the growth hormone response to thyrotropin-releasing hormone and to luteinizing hormone-releasing hormone in adolescents but not in adults, may reflect developmental changes interacting with disease processes. Still other abnormalities may be more directly reflective of different disease processes: a rapidly neuroleptic-responsive and good-prognosis psychotic disorder appears to be associated with blunted thyrotropin response to thyrotropin-releasing hormone and a blunted growth hormone response to apomorphine; a relatively drug-responsive psychotic disorder whose response requires several weeks of neuroleptic treatment appears to be associated with an excessive growth hormone response to apomorphine. The neuroendocrine windows for viewing brain function in the schizophrenias still permit indistinct images of the processes that modulate their release. Nevertheless, the images may provide important clues to the biopathology underlying these diseases.