Striatal Dopaminergic D₂ Receptor Density Measured by [¹²³I]Iodobenzamide SPECT in the Prediction of Treatment Outcome of Alcohol-Dependent Patients

OBJECTIVE: The authors’ goal was to study striatal dopaminergic dopamine 2 (D₂) receptors as a biological marker of early relapse in detoxified alcoholic patients by using [¹²³I]iodobenzamide ([123I]IBZM) single photon emission computed tomography (SPECT). METHOD: The authors performed [¹²³I]IBZM SPECT on 21 alcohol-dependent inpatients during detoxification and on nine healthy volunteers, using the ratios of basal ganglia to occipital lobes for SPECT quantification. Depending on treatment outcome 3 months after hospital discharge, patients were determined to be relapsers or nonrelapsers. RESULTS: Alcohol-dependent subjects with early relapse (within 3 months after hospital discharge) showed a higher uptake of [¹²³I]IBZM in the basal ganglia during detoxification (mean ratio=1.83, SD=0.9) than patients who did not have early relapse (mean ratio=1.69, SD=0.11). CONCLUSIONS: These results suggest that low levels of dopamine, or an increased density of free striatal dopaminergic D₂ receptors, could be related to early relapse in alcohol-dependent patients. Therefore, [¹²³I]IBZM SPECT could become a biological marker of vulnerability to relapse for alcoholic patients in recovery.