Dopamine and serotonin transporters in patients with schizophrenia: An imaging study with [I-123]beta-CIT

Background: Several lines of evidence derived from imaging and postmortem s tudies suggest that schizophrenia is associated with hyperactivity of dopam ine function and deficiency in serotonin (5-HT) function. The aim of this s tudy was to investigate potential alterations of striatal dopamine transpor ters (DAT) and brainstem serotonin transporters (SERT) density in schizophr enia. Methods: Striatal DAT and brainstem SERT were measured in 24 patients with schizophrenia and 22 matched healthy control subjects using single photon e mission computed tomography and [I-123]beta-CIT. In this cohort of subjects , we previously reported an increase in striatal amphetamine-induced dopami ne release, measured as the displacement of the D-2 receptor radiotracer [I -123]IBZM. Results: No differences were observed between patients and control subjects in the equilibrium uptake ratio (V-3") of [I-123]beta-CIT in the striatum, indicating that schizophrenia is not generally associated with an alterati on of striatal DAT density; however a trend level association (p = -.07) wa s observed in patients with schizophrenia between low striatal [I-123]beta- CIT V-3" and severity of negative symptoms. After controlling for age, stri atal [I-123]beta-CIT V-3" in patients was not associated with duration of i llness, suggesting that this relative deficit was not secondary to a neurod egenerative process. No correlation was observed between DAT density and am phetamine-induced dopamine release, either in the patients or in the contro ls. Brainstem [I-123]beta-CIT V-3" was unaffected in patients with schizoph renia, and was unrelated to symptomatology. Conclusions: Schizophrenia is generally not associated with alterations of DAT in the striatum or SEPT in the brainstem. In some patients, a relative deficit in dopamine nerve terminals might play a role in the pathophysiolog y of negative symptoms. (C) 2000 Society of Biological Psychiatry.