Striatal D1 and D2 receptor binding in patients with Huntington's disease and other choreas. A PET study.

We have used PET to study striatal D1 and D2 receptor binding in 10 patients with either the choreic or akinetic-rigid variants of Huntington's disease and in three patients with other causes of chorea. Background rigidity and bradykinesia in choreic patients were scored with a four-point scale. PET studies showed a severe and parallel reduction of both striatal D1 and D2 receptor binding in Huntington's disease patients irrespective of their predominant phenotype (mean reduction 60%). Huntington's disease patients with rigidity showed more pronounced reduction of striatal D1 and D2 binding compared with those without rigidity. A case of chorea associated with systemic lupus erythematosus had normal D2 binding. These results suggest that the presence of chorea per se may not be determined by alterations in striatal dopamine receptor binding, but that rigidity in Huntington's disease is associated with severe striatal D1 and D2 receptor loss.