Decrease in human striatal dopamine D2 receptor density with age: A PET study with [11C]raclopride

Abstract

The effect of age on human striatal dopamine D2 receptors was investigated with positron emission tomography (PET) using [11C]raclopride as a radioligand. Twenty-one healthy volunteers aged from 20 to 81 years were studied. An equilibrium method was applied and two separate PET scans with different specific activities of [11C]raclopride were performed. The maximal number of receptors (Bmax) and their dissociation constant (Kd) were calculated using Scatchard analysis. There was an age-dependent decline in the Bmax (r = -0.49; p = of striatal D2 receptors while the Kd remained unchanged. The results show that there is an age-related loss of atal D2 receptors, which, together with other changes the brain nigrostriatal dopaminergic system, may countinute to extrapyramidal symptoms associated with organisation.