Imaging brain cholinergic activity with positron emission tomography: Its role in the evaluation of cholinergic treatments in Alzheimer's dementia

One of the strategies in the treatment of Alzheimer's disease is the use of drugs that enhance cholinergic br ain function, since it is believed that cholinergic dysfunction is one of the factors that contributes to cognitive deterioration.. Positron emission tomography is a medical imaging method t hat can be used to measure the concentration, kinetics, and distribution of cholinergic-enhancing drugs directly in the human brain and assess the eff ects of the drugs at markers of cholinergic cell viability (vesicular trans porters, acetylcholinesterase), at muscarininc and nicotinic receptors, at extracellular acetylcholine, at markers of brain function (glucose metaboli sm and blood flow), and on amyloid plaque burden in vivo in the brains of p atients with Alzheimer's disease. In addition, these measures call be appli ed to assess the drugs' pharmacokinetic and pharmacodynamic properties in t he human brain. Since the studies ale done in living human subjects, positr on emission tomography can evaluate the relationship between the drugs' bio logical, behavioral, and cognitive effects; monitor changes in brain functi on in response to chronic treatment; and determine if phamacologic interven tions are neuroprotective. Moreover, because positron emission tomography h as the potential to identify Alzheimer's disease during early disease, if c an be used to establish whether early interventions cai? prevent or delay f uther development.