STRIATAL D-1 AND D-2 RECEPTOR-BINDING IN PATIENTS WITH HUNTINGTONS-DISEASE AND OTHER CHOREAS - A PET STUDY

We have used PET to study striatal D-1 and D-2 receptor binding in 10 patients with either the choreic os akinetic-rigid variants of Hunting ton's disease and in three patients with other causes of chorea. Backg round rigidity and bradykinesia in choreic patients were scored with a four-point scale. PET studies showed a severe and parallel reduction of both striatal D-1 and D-2 receptor binding in Huntington's disease patients irrespective of their predominant phenotype (mean. reduction 60%). Huntington's disease patients with rigidity showed more pronounc ed reduction of striatal D-1 and D-2 binding compared with those witho ut rigidity. A case of chorea associated with systemic lupus erythemat osus had normal D-2 binding. These results suggest that the presence o f chorea per se may not be determined by alterations in striatal dopam ine receptor binding, but that rigidity in Huntington's disease is ass ociated with severe striatal D-1 and D-2 receptor loss.