Navigation Links
Alzheimer's Research Brings Progress, Setbacks
Date:7/18/2008

Once-promising vaccine fails to ease symptoms, but old drug offers new hope

FRIDAY, July 18 (HealthDay News) -- It's one step forward, one step back in the search for treatments against Alzheimer's disease.

In one of two studies in the July 19 issue of The Lancet, an older drug called dimebon significantly improved Alzheimer's symptoms. But in a second report, a once-promising vaccine failed to prevent the progression of Alzheimer's -- even though it cleared dementia-linked amyloid plaques in the brain.

This week's issue of the journal is devoted to research into the causes and treatment of dementia, including Alzheimers disease. According to the U.S. National Institutes of Health, an estimated 4.5 million Americans have Alzheimer's disease, which is thought to affect one in 20 people between the ages of 65 and 74. The estimated rate goes up to nearly half of those aged 85 and older.

In one study, British researchers led by Dr. Clive Holmes, from the Memory Assessment and Research Centre at Moorgreen Hospital in Southampton, analyzed data on 80 Alzheimer's patients who were treated with an experimental vaccine that for now is dubbed AN1792.

The vaccine is targeted at the removal of amyloid protein plaques that clump around brain cells in increasing numbers as Alzheimer's progresses. The theory was that dementia could be slowed or reversed once the plaques were cleared, and experiments in animals have shown that removing these plaques improves brain function.

Indeed, long-term follow-up of Alzheimer's patients treated with AN1792 did show, "a reduction in the number of plaques in the brains of patients -- in some cases there was a virtually complete removal of plaques," Holmes said.

But there was a catch. "Crucially, there was no evidence that the patients benefited by the removal of plaques and even those subjects with virtually complete removal continued to deteriorate and had severe end-stage dementia prior to their death," Holmes said.

Based on these results, the researcher now believes that removing plaques -- at least by this method -- is unlikely to make a significant difference to the clinical outcome of patients with established Alzheimer's disease. "In addition, it strongly suggests that plaques are not sufficient on their own to account for disease progression," Holmes said.

Based on the findings, novel strategies for the treatment of Alzheimer's disease should not focus on the removal of plaques in patients with established Alzheimer's, Holmes contends. "Treatments should move towards preventing plaques from building up in the first place," he said. "Or in established Alzheimer's disease, treatments should focus more on non-plaque therapies."

Dr. Sam Gandy, chairman of the Alzheimer's Association's National Medical and Scientific Advisory Council, said the new finding suggests that other forces besides plaque build-up are driving disease progression.

"If you don't start with your vaccine until you are at a later stage of disease and other processes are already established, the horse may be already out of the barn," Gandy said. "It is possible that amyloid is like a match lighting a fire and once the fire is out of control, dealing with the match isn't that effective."

But there was better news in a second study. In that work, Dr. Rachelle S. Doody, a professor of neurology at the Alzheimer's Disease and Memory Disorders Center at Baylor College of Medicine in Houston, and her colleagues studied the effects of the drug dimebon on 183 patients in Russia with mild to moderate Alzheimer's disease. The drug is currently not marketed anywhere, and was previously used in Russia as an antihistamine.

"This is a medication that has not previously been studied in Alzheimer's disease," Doody said. In the trial, patients were randomly assigned to 20 milligrams of dimebon three times a day, or a placebo.

After six months, Doody's team found that patients on dimebon had significant improvement in cognitive ability, compared with those receiving placebo.

"We found treated patients were improved in their thinking abilities, their behavioral symptoms [and] their daily skills abilities, compared to people who took placebo," she said.

The patients were evaluated using ADAS-cog, a battery of tests that assesses a person's ability to track dates, comprehend instructions, follow commands, memorize word lists, and complete simple tasks such as copying drawings or addressing an envelope.

At six months, patients receiving dimebon showed an improvement of 1.9 points on the ADAS-cog scale from the beginning of the study, while those on placebo continued to decline. After a year, those receiving dimebon showed a 6.9 point increase on the ADAS-cog scale, the researchers report.

"This first trial was promising," Doody said. "This is not a cure for Alzheimer's disease, but the benefits could last for a long time. The drug appears to slow the clinical progression of the disease."

The study was done in Russia because dimebon had been approved there as an antihistamine. Dimebon is made by the San Francisco-based biopharmaceutical company Medivation. Doody is on the Scientific and Clinical Advisory Board of Medivation and has stock options in the company.

Another phase III trial has just started, Doody said. This six-month trial is being conducted in the United States, Europe and South America and is now in the process of recruiting several hundred patients, she noted.

"We are anxiously awaiting the completion of the next study, so that we can see if this drug could potentially be approved for treating Alzheimer's patients," Doody said.

Gandy said the drug does appear to be superior to the currently approved medicines for Alzheimer's.

"This is the first new promising symptomatic therapy in a long time," Gandy said. "This drug could potentially add to the effects of other drugs such as Aricept, Namenda and Exelon," he said. "I think it's a pretty exciting development."

More information

For more information on Alzheimer's disease, visit the Alzheimer's Association.



SOURCES: Clive Holmes, M.D., Ph.D., Memory Assessment and Research Centre, Moorgreen Hospital, Southampton, UK; Rachelle S. Doody, M.D., Ph.D., professor, neurology, Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, Houston; Sam Gandy, M.D., chairman, Alzheimer's Association National Medical and Scientific Advisory Council; July 19, 2008, The Lancet


'/>"/>
Copyright©2008 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Alzheimers Research Target May Be a Dead End
2. Stanford researchers find culprit in aging muscles that heal poorly
3. Children of depressed moms do better when dad is involved, SLU researcher finds
4. UCLA researchers identify markers that may predict diabetes in still-healthy people
5. Mayo Clinic researchers discover new diagnostic test for detecting infection in prosthetic joints
6. New research shows how chronic stress worsens neurodegenerative disease course
7. New research explores newborn in-hospital weight loss
8. Research may unlock mystery of autisms origin in the brain
9. Bipolar disorder relapses halved by Melbourne researchers
10. HIVs impact in Zimbabwe explored in new research
11. U.S. Research Funding Continues to Flatten as U.S. Health Costs Climb - in August 31 Science
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Alzheimer's Research Brings Progress, Setbacks
(Date:6/25/2016)... ... June 25, 2016 , ... Conventional wisdom preaches the benefits of moderation, whether ... latter, setting the bar too high can result in disappointment, perhaps even self-loathing. However, ... their goal. , Research from PsychTests.com reveals that behind the tendency ...
(Date:6/24/2016)... ... June 24, 2016 , ... Those who have experienced traumatic events may suffer ... unhealthy avenues, such as drug or alcohol abuse, as a coping mechanism. To avoid ... healthy coping following a traumatic event. , Trauma sufferers tend to feel a range ...
(Date:6/24/2016)... ... ... Marcy was in a crisis. Her son James, eight, was out of control. Prone to ... , “When something upset him, he couldn’t control his emotions,” remembers Marcy. “If there ... my other children and say he was going to kill them. If we were ...
(Date:6/24/2016)... ... 2016 , ... Global law firm Greenberg Traurig, P.A. announced that 20 Florida ... their peers for this recognition are considered among the top 2 percent of lawyers ... as members of this year’s Legal Elite Hall of Fame: Miami Shareholders Mark ...
(Date:6/24/2016)... CA (PRWEB) , ... June 24, 2016 , ... Comfort ... the American Cancer Society and the Road To Recovery® program to drive cancer patients ... seniors and other adults to ensure the highest quality of life and ongoing independence. ...
Breaking Medicine News(10 mins):
(Date:6/26/2016)... , June 27, 2016  VMS Rehab Systems, Inc. ... will take whatever measures required to build a strong ... which is currently listed on the OTC Markets-pink current ... Chairman and CEO, "We are seeing an anomaly in ... understand, not only by the Company, but shareholders and ...
(Date:6/24/2016)... 2016  Consumers have taken a more active ... more emphasis on patient outcomes. ... the pharmaceutical industry have evolved beyond just providing ... are focusing on becoming more patient-oriented across their ... services that improve health. ...
(Date:6/24/2016)... FRANCISCO, Calif. , June 24, 2016 /PRNewswire/ ... ), a biopharmaceutical company developing novel therapeutics for ... unmet needs, today announced the closing of its ... of common stock, at the public offering price ... in the offering were offered by GBT. GBT ...
Breaking Medicine Technology: