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Introduction
The primary symptoms of Alzheimers disease include
memory loss, disorientation, confusion, and problems with
reasoning and thinking. These symptoms worsen as brain cells
die and the connections between cells are lost. Although current
drugs cannot alter the progressive loss of cells, they may
help minimize or stabilize symptoms. These medications may
also delay the need for nursing home care.
Cholinesterase Inhibitors
The U.S. Food and Drug Administration (FDA) has approved
two classes of drugs to treat cognitive symptoms of Alzheimer’s
disease. The first Alzheimer medications to be approved were
cholinesterase (KOH luh NES ter ays) inhibitors. Three
of these drugs are commonly prescribed—donepezil (Aricept®),
approved in 1996; rivastigmine (Exelon®), approved in
2000; and galantamine (Reminyl®), approved in 2001. Tacrine
(Cognex®), the first cholinesterase inhibitor, was approved
in 1993 but is rarely prescribed today because of associated
side effects, including possible liver damage.
All of these drugs are designed to prevent the breakdown
of acetylcholine (pronounced a SEA til KOH lean), a
chemical messenger in the brain that is important for memory
and other thinking skills. The drugs work to keep levels of
the chemical messenger high, even while the cells that produce
the messenger continue to become damaged or die. About half
of the people who take cholinesterase inhibitors experience
a modest improvement in cognitive symptoms.
For more information, see the Cholineterase
Inhibitors Fact Sheet.
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Memantine
Memantine (Namenda®) is a drug approved in October 2003
by the FDA for treatment of moderate to severe Alzheimer’s
disease.
Memantine is classified as an uncompetitive low-to-moderate
affinity N-methyl-D-aspartate (NMDA) receptor antagonist,
the first Alzheimer drug of this type approved in the United
States. It appears to work by regulating the activity of glutamate,
one of the brain’s specialized messenger chemicals involved
in information processing, storage and retrieval. Glutamate
plays an essential role in learning and memory by triggering
NMDA receptors to allow a controlled amount of calcium to
flow into a nerve cell, creating the chemical environment
required for information storage.
Excess glutamate, on the other hand, overstimulates NMDA
receptors to allow too much calcium into nerve cells, leading
to disruption and death of cells. Memantine may protect cells
against excess glutamate by partially blocking NMDA receptors.
For more information, see the Memantine
Fact Sheet.
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Vitamin E
Vitamin E supplements are often prescribed as a treatment
for Alzheimers disease, because they may help brain
cells defend themselves from attacks. Normal cell
functions create a byproduct a called free radical, a kind
of oxygen molecule that can damage cell structures and genetic
material. This damage, called oxidative stress, may play a
role in Alzheimers disease.
Cells have natural defenses against this damage, including
the antioxidants vitamins C and E, but with age some of these
natural defenses decline. Research has shown that taking vitamin
E supplements may offer some benefit to people with Alzheimers.
Most people can take vitamin E without side effects. However,
any change in medications should first be discussed with a
primary care physician because all medication can cause side
effects or interactions with other medications. A person taking
blood-thinners, for example, may not be able to
take Vitamin E or will need to be monitored closely by a physician.
For more information, see the Vitamin
E Fact Sheet.
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