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Back to Neurology Articles

 Friday, 5 November 2004 05:30 PM


New drugs may help in blocking the accumulation of the brain-clogging beta-amyloid protein thought to cause Alzheimer's disease.


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  Donepezil effective for severe Alzheimer's disease  

This month witnessed the discovery of two drugs that may help in treating Alzheimer's disease. On the other hand, it has been announced that a large-scale study will be launched next April with the aim of better understanding this disease.

Alzheimer's disease (AD) affects approximately 4.5 million Americans. It is considered the most common cause of dementia in western countries. Approximately 10% of all persons over the age of 70 have significant memory loss; in more than half, the cause is AD. AD is a progressive dementia (that is the dementia keeps getting worse).

The most important risk factors for AD are old age and a positive family history. The frequency of AD increases with each decade of adult life to reach 20 to 40% of the population over the age of 85. A positive family history of dementia suggests a genetic cause of AD.


AD is characterized in the brain by abnormal clumps (amyloid plaques) and tangled bundles of fibers (neurofibrillary tangles) composed of misplaced proteins. Three genes have been discovered that cause early onset (familial) AD. Other genetic mutations that cause excessive accumulation of amyloid protein are associated with age-related (sporadic) AD.

The management of Alzheimer's disease is difficult and frustrating, because there is no specific treatment and no way to slow the progression of the disease. The primary focus is on long-term amelioration of associated behavioral and neurologic problems. Currently there are five FDA-approved drugs that may benefit some people in the early or middle stages of the disease. Tacrine (Cognex) may alleviate some cognitive symptoms. Donepezil (Aricept), rivastigmine (Exelon), and galantamine (Reminyl) may keep some symptoms from becoming worse for a limited time.

"In recent studies, the benefit of  these medications were shown to be more effective in the early and middle stages of Alzheimer's and less effective in the last stage", comments Carolyn Merritt, LPN of The Doctors Lounge. "The studies seemed to show it delayed the onset of the third and final stage".

The fifth drug, memantine (Namenda), was recently approved for use in the United States.

US launches major study

In April 2005, researchers will begin recruiting about 800 Americans, ranging from 55 to 90 years old, in an effort to gain a better understanding of the early stages of the disease. This will be part of a major government study to track early Alzheimer's disease.

Researchers will use MRIs of the brain and other tests to track people who have either early-stage disease or a milder type of memory loss known as "mild cognitive impairment." Over the course of five years, they will compare the biological changes that occur within those patients' brains to the aging that takes place in the brains of healthy seniors.

The goal is to find early warning signs that can identify people at highest risk, and markers to help test the effectiveness of new therapies. The study, which will cost approximately $60 million (mostly funded by the government), was unveiled Wednesday by the National Institute on Aging.

New hope

In the lab, scientists said they had designed a drug that appears to block the accumulation of the brain-clogging beta-amyloid protein. The study was published in last week's issue of the journal Science. This new drug, although promising, is still in its pre-clinical testing stage. Scientists will now proceed to test it in animal models with versions of Alzheimer's disease.

Earlier this week, a team at the National Institute of Environmental Health Sciences and the University of Wisconsin said they found a naturally occurring brain protein that stops the progression of Alzheimer's disease in human brain tissue. The protein, called transthyretin, appears to protect brain cells by intercepting beta-amyloid protein before it can damage brain tissue. Drugs that boost transthyretin levels may help treat or even prevent the disease.


Dr. Tamer Fouad, M.D.

Edited by:

Dr. Russell Musthafa

Carolyn Merritt (Licensed Practical Nurse).

Reviewed by:

Dr. Yasser Mokhtar, M.D.

Theresa Jones (Registered Nurse).


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