Serum prolactin levels in unmedicated first-episode and recurrent schizophrenia patients: a possible marker for the disease's subtypes

Various studies indicate that we must consider schizophrenia not as a single disease but as several distinct etiological processes that give rise to characteristic symptoms. In the current study, we aimed to examine prolactin serum levels in unmedicated first-episode and recurrent schizophrenic patients. The prolactin levels were compared among the different schizophrenia subtypes, i.e. paranoid, schizoaffective and disorganized. Prolactin serum samples were assessed on the morning after the admission in 48 first-episode and 38 recurrent unmedicated hospitalized schizophrenia patients. Two psychiatrists made the diagnosis without knowledge of laboratory results and completed the rating scales. Despite all prolactin levels being within or close to the normal range, we found significant differences in prolactin serum levels among schizophrenia subtype patients: the lowest values were for the paranoid type, intermediate for the schizoaffective and the highest for the disorganized patients. The results seem to indicate a pronounced hyperdopaminergic activity in paranoid schizophrenia, suggesting differences in dopaminergic tone between the schizophrenia subtypes, and support the clinical and the neuropsychological individuality of disease subtypes. There were no significant differences in prolactin serum levels of the schizophrenia subtypes between the first-episode and the recurrent patients. It appears that there are constant patterns of dopamine bioactivity in acutely psychotic unmedicated schizophrenia patients, whether the patients are first admitted or recurrent. (C) 2004 Elsevier Ireland Ltd. All rights reserved.