Reduced levels of GABA-benzodiazepine receptor in alcohol dependency in the absence of grey matter atrophy

Background We tested the hypothesis that reduced levels of the GABA-benzodiazepine receptor occur in alcohol dependency using single photon emission tomography (SPET) and the specific GABA-benzodiazepine ligand, (123I)-iomazenil. Method Neurologically and cognitively unimpaired abstinent alcohol-dependent (n=12) and non-alcohol-dependent male subjects (n=14) underwent a I-123-iomazenil SPET scan. SPET and magnetic resonance images were co-registered and voxel-based statistical tests performed. Subjects' clinical and alcohol history were obtained with standard questionnaires. The relationships between clinical and alcohol variables and the regional level of GABA-benzodiazepine receptors were investigated using multiple regression analysis. Results Abstinent alcohol-dependent subjects had decreased levels of GABA- benzodiazepine receptor compared with non-alcohol-dependent subjects within the frontal, parietal and temporal cortices, including regions in which grey matter atrophy was absent, Conclusions Alcohol dependency is associated with reduced GABA-benzodiazepine receptor levels in the absence of grey matter atrophy in some cortical regions, such as within the parietal robe. Regional variability of reduction in GABA-benzodiazepine receptors demonstrates that alcohol does not have a global, toxic effect on the brain.