Levels of gamma-aminobutyric acid-benzodiazepine receptors in abstinent, alcohol-dependent women: preliminary findings from an 123I-iomazenil single photon 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 effects of alcohol. However, no in vivo studies of the neuropharmacology of alcohol dependence in women have been carried out. The aim of this preliminary study was to test the hypothesis that alcohol dependence in women is associated with greater reduction in gamma-aminobutyric acid (GABA)-benzodiazepine receptor levels than in men with an equivalent drinking history.

METHODS

We used single photon emission tomography and 123I-iomazenil to label 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 receptor 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 pattern of reduction seen in the previous study of male dependence, where significant reductions were seen primarily in the frontal cortex.

CONCLUSIONS

Due to the semiquantitative analysis performed and the relatively small number of subjects in this study, which resulted in a nonsignificant trend, we can only comment on the differences in the pattern of lower levels of GABA-benzodiazepine receptors seen in alcohol dependence in men and 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 differential effect on the central GABA-benzodiazepine receptors in men and women. Recent animal evidence supports this hypothesis. Future studies should explore whether other neuropharmacological differences exist between men and women in alcohol dependence that could have implications for pharmacotherapy.