Levels of gamma-aminobutyric acid-benzodiazepine receptors in abstinent, alcohol-dependent women: Preliminary findings from an I-123-iomazenil singlephoton emission tomography study

Background: Although alcohol dependence in women is an increasing problem, little is known about the effects of alcohol on the female brain. Evidence from a few structural and functional neuroimaging studies suggests that the female brain may be more susceptible than the male brain to the harmful ef fects of alcohol. However, no in vivo studies of the neuropharmacology of a lcohol dependence in women have been carried out. The aim of this prelimina ry study was to test the hypothesis that alcohol dependence in women is ass ociated with greater reduction in gamma-aminobutyric acid (GABA)-benzodiaze pine receptor levels than in men with an equivalent drinking history. Methods: We used single photon emission tomography and I-123-iomazenil to l abel the central GABA-benzodiazepine receptor and to compare semiquantified levels in 9 abstinent alcohol-dependent and 13 control women. These groups were further compared with equivalent male groups from a previous study. Results: There was a trend toward a reduction in GABA-benzodiazepine recept or levels in alcohol-dependent women, but this did not reach significance. These lower levels were seen primarily in the cerebellum, occipital lobes, and parietal cortex (left > right). This was in marked contrast with the pa ttern of reduction seen in the previous study of male dependence, where sig nificant reductions were seen primarily in the frontal cortex. Conclusions: Due to the semiquantitative analysis performed and the relativ ely small number of subjects in this study, which resulted in a nonsignific ant trend, we can only comment on the differences in the pattern of lower l evels of GABA-benzodiazepine receptors seen in alcohol dependence in men an d women. Although we are not able to ascertain whether the female brain is more susceptible to the effects of alcohol, it appears that alcohol has a d ifferential effect on the central GABA-benzodiazepine receptors in men and women. Recent animal evidence supports this hypothesis. Future studies shou ld explore whether other neuropharmacological differences exist between men and women in alcohol dependence that could have implications for pharmacot herapy.