Different pattern of reduction of striatal dopamine reuptake sites in Alzheimer's disease and ageing.

Striatal dopamine reuptake sites were studied in brain samples from 14 Alzheimer's disease (AD) patients. A cocaine analogue, [3H]CFT (WIN 35,428, 2beta-carbomethoxy-3beta-(4-fluorophenyl)-tropane) was used as a radioligand to determine the number of [3H]CFT binding sites (Bmax) and their dissociation constant (Kd). In patients with AD the reduction in [3H]CFT binding in the putamen was about 50% compared to age-matched controls. In the caudate nucleus the reduction was about 33%. Thus, the putamen was more severely affected. No change was observed in Kd values between AD patients and controls. Brain samples from 37 healthy controls (aged from 8 to 91 years) were used to study the changes in striatal [3H]CFT binding with increasing age. The Bmax of [3H]CFT uptake was reduced both in the putamen and in the caudate nucleus. The average decline per decade was greater in the caudate nucleus (7.3%) than in the putamen (5.5%). In conclusion, the pattern of changes in AD is different from that seen during normal ageing, which seems to affect more severely the caudate nucleus than the putamen.