Sensitivity of GABAergic systems in male alcoholics and subjects at risk for alcoholism

To test the hypothesis that the sensitivity of GABAergic systems is reduced in alcohol dependence, we investigated the correlation between regional cerebral glucose metabolism (rCGM) and EEG alpha power before and after pharmacological suppression of alpha activity by lorazepam. 10 male alcoholics, 10 subjects at risk for alcoholism, and 18 healthy male controls underwent two 18-FDG PET scans with simultaneous EEG recording: 1x placebo, 1x lorazepam (30µg/kg). Controls showed a reduction in rCGM bilaterally in thalamus and in occipital cortex in response to lorazepam as well as a significant reduction of EEG alpha power. There was a positive correlation of alpha power to the bilateral thalamus and to the parieto-occipital cortex, whereas only the thalamic correlation remained under lorazepam induced alpha suppression. Our results confirm the role of the thalamus as the generator of EEG alpha rhythm. Data obtained in the other two samples are currently being analyzed.