Decreased densities of dopamine D1 receptors in the putamen and hippocampus in senile dementia of the Alzheimer type.

The density and distribution of dopamine D1 receptors as labeled with [3H]SCH 23390 was analyzed in post-mortem brain tissue from patients with senile dementia of the Alzheimer type (SDAT) and in controls using quantitative autoradiography. In SDAT patients D1 receptor densities were markedly decreased in parts of the hippocampus, with reductions of up to 89% compared to the control values in the molecular layer of the dentate gyrus, 57% in the strata oriens and pyramidalis of the CA1 and 74% in the CA3 subfields. Significant decreases in D1 receptors were also observed in the putamen (23%) but not in the caudate and substantia nigra. A slight but not significant decrease of D1 binding was observed in most external layers of the temporal and occipital cortices.