Blunted serotonergic responsivity in neuroleptic-naïve patients at first-episode of schizophrenia

ObjectiveTo determine whether serotonergic responsivity, as assessed in platelets, is blunted in treatment-naïve patients with first episode psychosis, similar to observations in chronic schizophrenia.MethodsSerotonin (5-HT)-amplified platelet aggregation was determined in 26 first-episode treatment-naive patients with psychosis (14 with schizophrenia, 12 with mood disorders with psychosis) and 16 matched healthy comparison subjects. Platelet aggregation was measured in fresh whole blood after stimulation with 5.0 μM adenosine diphosphate (ADP) alone and with the addition of 0.2 μg and 1.0 μg 5-HT.ResultsHealthy subjects showed expected robust increases in platelet aggregation (+ 106% and + 146% at 0.2 μg and 1.0 μg 5-HT, respectively). By contrast, patients with schizophrenia showed almost no changes in aggregation (+ 6% and + 3%), while patients with mood disorders showed intermediate increases (+ 59% and + 66%).ConclusionsBlunted platelet serotonergic responsivity appears to be independent of treatment effects. To determine whether this is trait-related factor will require prospective studies.