Changes in platelet 5-hydroxytryptamine uptake in mania

[³H]5-Hydroxytryptamine (5HT) platelet uptake was examined in a small group of hospitalised drug-free manic patients and in a larger group of drug-treated manic and schizophrenic patients compared to controls. 5HT platelet uptake was significantly higher in the manic group at the beginning of the illness episode than in either schizophrenics or controls. No difference was found in the uptake rates between the schizophrenics and controls. At discharge, manic patients had 5HT uptake values similar to control subjects. Manic patients with no previous history of either mania or depression had highly significant increases in 5HT platelet uptake compared to either schizophrenics, controls or manic patients with a previous history of manic-depression. No correlation was found between the initial increased 5HT uptake rate in the manic patient and the severity or duration of the illness episode, the length of hospitalisation or the gender of the patient.