Amphetamine-induced dopamine release and post-synaptic specific binding in patients with mild tardive dyskinesia

Several lines of evidence suggest that changes in dopamine release and/or post-synaptic sensitivity may be involved in the pathogenesis of tardive dyskinesia (TD). Preclinically, increased D(2) receptor sensitivity and dopamine turnover are associated with D(2) receptor antagonism. Clinically, development of TD is associated with D(2) receptor antagonist administration. Eight patients with mild evidence of TD (AIMS ratings > or =14) and six without (AIMS = 10), underwent [(11)C]raclopride PET scans. Baseline and amphetamine-induced decrements in striatal specific binding were assessed. Baseline and amphetamine-induced decrements in specific binding did not differ between patients with and without evidence of mild TD (p =.53). AIMS ratings did not significantly correlate with baseline (p =.76) or decrements in specific binding (p =.45). This study provides evidence that TD is not associated with increased amphetamine-induced presynaptic dopamine release and/or D(2) receptor binding as measured by [(11)C]raclopride PET. More research is needed to unravel the neurobiology of this debilitating disorder.