Cholinesterase Inhibitors: Helping Nerves Communicate
Most people think of the nervous system as the body`s electrical wiring. This is correct -- but only up to a point.
Nerve cells transmit impulses much like wires transmit electricity. But unlike wires, which are continuous filaments, nerve cells do not touch one another. They have microscopic gaps between them called synapses. Nerve impulses must jump these gaps to proceed on their way. They do it with the help of special chemicals called neurotransmitters.
During the late 1970s, researchers discovered that people with Alzheimer`s disease suffer a loss of acetylcholine from their synapses. This observation fueled theories that Alzheimer`s might disrupt the synthesis of acetylcholine, or that the disease triggers overproduction of the enzyme that eliminates it, acetylcholinesterase -- generally known as cholinesterase. Scientists speculated that drugs to either increase acetylcholine or inhibit cholinesterase might help treat Alzheimer`s disease.
Cholinesterase inhibition has yielded the most promising results so far. The three drugs currently approved for treatment of Alzheimer`s -- Cognex (tacrine), Aricept (donepezil), and Exelon (rivastigmine) -- are all cholinesterase inhibitors. They do not cure Alzheimer`s disease, but can consistently produce small improvements in memory and function. Some people may even notice improvement in their ability to perform daily activities.
Several additional cholinesterase inhibitors are also being developed, and a few, such as Promem (metrifonate from Bayer Corporation Pharmaceutical Division), are close to Food and Drug Administration (FDA) approval. (Bayer Corporation Pharmaceutical Division is the provider of an unrestricted educational grant to Alzheimers.com).