Striatal presynaptic dopamine in schizophrenia, part II: Meta-analysis of [18F/11C]-DOPA PET studies

Abstract

Background: Alterations in striatal dopamine neurotransmission are central to the emergence of psychotic symptoms and to the mechanism of action of antipsychotics. Although the functional integrity of the presynaptic system can be assessed by measuring striatal dopamine synthesis capacity (DSC), no quantitative meta-analysis is available. Methods: Eleven striatal (caudate and putamen) [11C/18F]-DOPA positron emission tomography studies comparing 113 patients with schizophrenia and 131 healthy controls were included in a quantitative meta-analysis of DSC. Demographic, clinical, and methodological variables were extracted from each study or obtained from the authors and tested as covariates. Hedges' g was used as a measure of effect size in Comprehensive Meta-Analysis. Publication bias was assessed with funnel plots and Egger's intercept. Heterogeneity was addressed with the Q statistic and I2 index. Results: Patients and controls were well matched in sociodemographic variables (P >. 05). Quantitative evaluation of publication bias was nonsignificant (P =. 276). Heterogeneity across study was modest in magnitude and statistically nonsignificant (Q = 19.19; P =. 078; I2 = 39.17). Patients with schizophrenia showed increased striatal DSC as compared with controls (Hedges' g = 0.867, CI 95% from 0.594 to 1.140, Z = 6.222, P