Blunted serotonergic responsivity in neuroleptic-naïve patients at first-episode of schizophrenia.
OBJECTIVE
To determine whether serotonergic responsivity, as assessed in platelets, is blunted in treatment-naïve patients with first episode psychosis, similar to observations in chronic schizophrenia.


METHODS
Serotonin (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 microM adenosine diphosphate (ADP) alone and with the addition of 0.2 microg and 1.0 microg 5-HT.


RESULTS
Healthy subjects showed expected robust increases in platelet aggregation (+106% and +146% at 0.2 microg and 1.0 microg 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%).


CONCLUSIONS
Blunted platelet serotonergic responsivity appears to be independent of treatment effects. To determine whether this is trait-related factor will require prospective studies.
Reddy
Ravinder
R
Department of Psychiatry, University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, Pittsburgh, PA 15213, USA. reddyr@upmc.edu
Keshavan
Matcheri
M
Yao
Jeffrey K
JK
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D003865:Major Depressive Disorder / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D011618:Psychotic Disorders / Q000097:blood*; D012016:Reference Values; D012559:Schizophrenia / Q000097:blood*; D012701:Serotonin / Q000494:pharmacology*
D012701:Serotonin; D000244:Adenosine Diphosphate