Adaptations in γ-aminobutyric acid type A (GABAA)–benzodiazepine receptors contribute to the neurobiology of human alcohol dependence and withdrawal.
To study GABAA-benzodiazepine receptor adaptations in subjects with alcohol dependence over the first month of sobriety.
Inpatients who were not receiving medication, were either smokers or nonsmokers, and had alcohol dependence completed 2 iodine I 123–labeled iomazenil single-photon emission computed tomographic scans: 1 scan at a mean ± SD of 4.9 ± 2.5 days of sobriety (n = 23) and 1 scan at a mean ± SD of 29.8 ± 7.6 days of sobriety (n = 20). Participants in a matched group of healthy subjects (n = 15) completed 1 single-photon emission computed tomographic scan.
Men with alcohol dependence (n = 27) and a matched healthy comparison group (n = 15).
Main Outcome Measures
123I-iomazenil single-photon emission computed tomographic images were converted to units of distribution volume (regional activity/free 123I-iomazenil) and were analyzed using voxel-based statistical parametric mapping and regions of interest analyses. The relationships between 123I-iomazenil distribution volume, clinical features of alcohol dependence, and smoking status were evaluated.
123I-iomazenil uptake was elevated in several cortical regions, with a more prominent increase in nonsmokers with alcohol dependence as compared with smokers with alcohol dependence at 1 week of abstinence from alcohol. No significant differences were observed at 4 weeks of abstinence. At 1 week of abstinence, frontal 123I-iomazenil uptake correlated with the severity of alcohol withdrawal and the number of days since the last alcoholic drink was consumed. No significant associations were observed for smokers with alcohol dependence.
These data demonstrate time-dependent regulation of cortical GABAA-benzodiazepine receptors associated with the recovery from alcohol dependence. Higher GABAA-benzodiazepine receptor levels during acute withdrawal may reflect a compensation for reduced receptor function, which is thought to contribute to alcohol tolerance and withdrawal. The subsequent decline may reflect “normalization” of GABAA receptor function with sobriety. Smoking may attenuate GABAA receptor adaptations associated with alcohol dependence and may contribute to the comorbidity between alcoholism and smoking.