Acetylcholine & Alzheimer's Disease

Overview

Acetylcholine, or ACh, is a chemical messenger that stimulates nerve cells in the brain and peripheral nervous system. Nerve cells that utilize ACh as a messenger are called cholinergic neurons. The "cholinergic hypothesis" was the first hypothesis put forth that proposed a causal mechanism for Alzheimer's disease. A review perspective in the June 2003 issue of "The Journal of Pharmacology and Experimental Therapeutics" stated the cholinergic hypothesis was presented over 20 years ago and it implies that the degeneration and decreased function of neurons that utilize ACh contribute to memory loss and decreased cognitive function in aging populations and in those with Alzheimer's disease. The authors of this perspective further report that this hypothesis remains valid and treatment strategies directed at improving the function of cholinergic neurons is a rational approach for drug development.

Alzheimer's Disease

The Alzheimer's Association reports that Alzheimer's disease accounts for between 60 and 80 percent of all dementia cases and afflicts 5.3 million Americans. During the progression of this disease, memory and cognition are increasingly impaired. The degeneration of cholinergic neurons in certain areas of the brain is commonly observed in the brains of deceased Alzheimer's patients. Other pathologies found in the brains of persons with Alzheimer's include beta amyloid plaques and tangles of protein fibers. A review article in "Neurochemistry International" states that cholinergic nerve degeneration and the formation of plaques and protein tangles in nerve cells contribute to the development and progression of Alzheimer's.

Tau Proteins.? www.rPeptide.com/Tau-Proteins

AD PD Research: Recombinant High Quality Tau Proteins ...

Sponsored Links

Aging

Advanced age is the number one risk factor for Alzheimer's disease. During the normal aging process, ACh levels decrease in the brain. A study in "The Journal of Geriatric Psychiatry and Neurology" reported that older people are much more sensitive to scopolamine, which blocks ACh activity in the brain, than younger persons. The decreased ACh levels are responsible for the decline in short-term memory that affects elderly people. This age-associated memory impairment is not Alzheimer's disease, which is characterized by a much greater loss of ACh in the brain, but indicates the normal role of ACh in memory and other cognitive functions.

Plaques and Tangles

Alzheimer's disease has been classified as a protein misfolding disease. In Alzheimer's disease proteins, like beta amyloid, aggregate or form tangles of fibers that prevent normal neuronal cell functioning. New studies, such as the one in "Current Molecular Medicine" report that these proteins and the cholinergic neurons interact. Research on the interactions of ACh with other known causative agents of Alzheimer's disease will eventually provide a more detailed mechanism of how this disease develops and progresses.

Drugs

The Alzheimer's Association reports that five prescription drugs have been approved by the Food and Drug Administration for the treatment of Alzheimer's disease, as of 2010. Donepezil, galantamine, rivastigmine and tacrine are cholinesterase inhibitors. The other, Memanatine, inhibits another receptor protein in the brain. Cholinesterase inhibitors block the enzyme cholinesterase from breaking down ACh and therefore increase ACh levels in the brain. These drugs are efficacious for the treatment of the symptoms of memory loss, language impairment and other cognitive deficits. These drugs do not cure Alzheimer's disease and do not delay its progression.

Behavior

In addition to cognitive deficits, patients with Alzheimer's disease often exhibit behavioral disorders like increased aggression, depression, anxiety, over activity and psychosis. A review study in the journal "Current Medical Research and Opinion" concluded that the cholinesterase inhibitor rivastigmine improved behavioral disturbances in patients with Alzheimer's, suggesting that ACh also plays a role in the manifestation of the behavioral symptoms associated with Alzheimer's disease.