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Alzheimer's Study Recovers Lost Memory Mayo Work Finds Efforts in Mice Give Hope to Sufferers

Posted on: Friday, 29 July 2005, 12:00 CDT

Spurring new hope for Alzheimer's patients, researchers at Mayo Clinic Jacksonville say they have found a way to reverse memory loss in laboratory mice.

During a 3 1/2-year study conducted in partnership with the University of Minnesota and Massachusetts General Hospital, researchers transplanted a human gene into mice, causing memory loss that worsened over time and mimicking the brain degeneration that occurs with Alzheimer's disease.

They then tested the mice's memory by putting them in a pool of water with a submerged platform, knowing the mice would swim to the platform to find dry ground.

When the platform was removed, researchers measured how much time the mice spent swimming where the platform should have been. Over time, the memory-impaired mice forgot about the platform and swam aimlessly around the pool.

Researchers then "turned off" the implanted gene that caused the artificial memory loss and the mice again began to swim to where the platform used to be.

These new findings suggest researchers may be able to reverse the effects of memory loss, even in patients who have lost some brain tissue, said Jada Lewis, lead investigator for one of two Mayo research groups.

Lewis estimated it would be from five to seven years before humans benefit from any type of treatment or clinical trial. She has several family members suffering form Alzheimer's, a driving force in her research, she said.

"These findings are so exciting and give us hope for the future," she said.

The study's results will be published in today's issue of the journal Science.

There is no known cause for Alzheimer's, a degenerative brain disease that causes a progressive decline in memory and cognitive abilities. The time from diagnosis to death varies -- it can be as little as three years if the person is over 80 when diagnosed or as long as 10 years if the patient is younger.

But the study is important because most Alzheimer's treatments focus on slowing the symptoms or preventing the disease from progressing.

"We have to figure out how mice do this after we turn off the switch, then we can figure out how humans can do it," Lewis said. "We are now working with [pharmaceutical] companies to try to find drugs that could help."

Researchers also found that one commonly thought cause of Alzheimer's -- tangled bundles of neurons -- stayed in the brains of the mice who regained their memory and actually increased in number. Lewis said this shows the tangles aren't a cause of dementia, as previously thought.

Not everyone considers the new findings a breakthrough. Senthil Meenrajan, a University of Florida assistant professor of medicine specializing in geriatrics, said the study is a significant first step, but he doesn't see it benefiting humans anytime soon.

"Most of the success [in Alzheimer's research] comes from animal studies and hasn't been shown in humans," Meenrajan said. "They have been genetic and molecular findings that aren't applicable to humans until far into the future. It's not like we're at the crossroads of something dramatic."cherie.black@jacksonville.com, (904) 359-4504

MAKING PROGRESS

Researchers reversed memory loss in mice by "turning off" an implanted human gene that causes memory loss.

If the gene can be turned off in the mice, researchers say the next step is to figure out whether it can be done in humans.

Researchers also are looking at existing drugs to see if they target the new findings in the brain.

Mayo researchers estimate that it may be another five to seven years before humans could benefit from any drugs or clinical trials related to this research.

Last month, Mayo Clinic Jacksonville researchers announced that they may have found a way to predict who will develop Alzheimer's disease. In that research, they studied blood and spinal fluid proteins in mice. The results would identify people vulnerable to the disease in the same way cholesterol levels can be used to predict the risk for heart disease.

Source: Florida Times Union

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