Dopamine Transporter Binding in Smokers and Nonsmokers

Abstract

Regional brain concentrations of dopamine transporters have been examined to elucidate the neurochemical substrates of neurologic and psychiatric conditions. Many of these conditions are associated with increased (or decreased) cigarette smoking prevalence; therefore, current smoking may confound the results of these investigations. This study determined whether healthy current smokers and nonsmokers exhibit differences in dopamine transporter (DAT) binding measured by Tc-99m TRODAT SPECT. Tc-99m TRODAT SPECT brain scans were retrospectively evaluated in 46 nonsmokers and 8 current smokers, all of whom had been recruited and screened as healthy controls for previous imaging studies. The scans were acquired approximately 3 hours after the intravenous administration of 740 MBq (20 mCi) of Tc-99m TRODAT and were reconstructed with a simple bandpass filter. Regions of interest (ROIs) were placed manually on subregions of the right and left basal ganglia and distribution volume ratios (DVRs) were compared for the smoker and nonsmoker groups. There were significant decreases in DAT binding in current smokers compared with nonsmokers in the caudate nuclei bilaterally, the right anterior putamen and the left posterior putamen. Reduced DAT binding in ROIs relevant to movement disorders as well as other neuropsychiatric conditions may have important implications for evaluating scans in these patient populations.