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Presynaptic Dopaminergic Dysfunction in Schizophrenia

2004; American Medical Association; Volume: 61; Issue: 2 Linguagem: Inglês

10.1001/archpsyc.61.2.134

1538-3636

Stephen McGowan, Andrew D. Lawrence, Tim Sales, Digby Quested, Paul M. Grasby,

Neural and Behavioral Psychology Studies

Context The dopamine overactivity hypothesis of schizophrenia remains one of the most influential theories of the pathophysiology of the illness. Radiotracer brain imaging studies are now directly testing aspects of the overactivity hypothesis. Objective To assess presynaptic dopaminergic function in a large cohort of patients with schizophrenia by means of [ 18 F]fluorodopa uptake and a high-sensitivity 3-dimensional positron emission tomograph. We predicted elevations in striatal [ 18 F]fluorodopa uptake and reductions in prefrontal cortical [ 18 F]fluorodopa uptake in patients with schizophrenia. Design Case-control study. Setting Research institute investigation recruiting hospital outpatients. Patients Sixteen male medicated hospital outpatients with a DSM-IV diagnosis of schizophrenia (mean age, 38 years) and 12 age-matched male volunteers free of psychiatric and neurologic illness. Intervention [ 18 F]fluorodopa positron emission tomographic scanning. Main Outcome Measure [ 18 F]fluorodopa uptake constant K i measured with statistical parametric mapping and region-of-interest analyses. Results Statistical parametric mapping ( P <.05 corrected) and region-of-interest analyses ( P <.01) showed increased [ 18 F]fluorodopa uptake, confined primarily to the ventral striatum in patients with schizophrenia. No reductions in prefrontal cortical [ 18 F]fluorodopa uptake K i were seen in the statistical parametric mapping and region-of-interest analyses, although dorsal anterior cingulate [ 18 F]fluorodopa K i correlated with performance on the Stroop Color-Word Test in both groups. Conclusions As in studies in unmedicated patients, presynaptic striatal dopamine dysfunction is present in medicated schizophrenic patients, adding further in vivo support for dopamine overactivity in the illness.