Neurotransmitter receptor imaging in Alzheimer's disease.

Recent developments in positron emission tomography and ligand binding techniques have allowed the visualization of regional metabolism and neuroreceptor distributions in the living human brain. For dopamine-D 2 and benzodiazepine receptors it has also been possible to determine neuroreceptor characteristics such as Bmax and Kd by performing in vivo saturation analysis of ligand binding to the receptors. Using 11-C raclopride and 11-C-Ro 15-1788 as ligands for dopamine-D 2 and benzodiazepine receptors respectively we have determined Bmax and Kd-values in healthy volunteers and patients with various types of neuropsychiatric disorders. These ligands were also used in order to determine the degree of receptor occupancy in psychiatric patients treated with different types of drugs interfering with these neuroreceptors. We have administered 11-C-deoxy-glucose, 11-C-raclopride and 11-C-Ro 15-1788 to patients with Alzheimer's disease in order to examine possible alterations of glucose utilization and neuroreceptor distribution and quantities in these patients. The preliminary results indicate that this approach may be useful for the analysis of degenerative alterations of neuron populations and neuroreceptor systems in Alzheimer's disease.