Effects of Age on Dopamine and Serotonin Receptors Measured by Positron Tomography in the Living Human Brain

D2 dopamine and S2 serotonin receptors were imaged and measured in healthy human subjects by positron emission tomography after intravenous injection of 11C-labeled 3-N-methylspiperone. Levels of receptor in the caudate nucleus, putamen, and frontal cerebral cortex declined over the age span studied (19 to 73 years). The decline in D2 receptor in males was different from that in females.