Researchers first manipulated the genetic makeup of the mice so they developed dementia; the mice experienced memory loss that worsens over time and had brain atrophy similar to what a person with Alzheimer's disease goes through. The researchers further designed the mice so that the transgene that causes these symptoms could be "turned off." Transgenes are genes from one organism that have been incorporated into another organism.
The researchers predicted that when the transgene expressing the dementia was turned off, memory loss would stop. The results, however, surpassed their expectations. The mice's symptoms of dementia were reversed--in other words, they regained memory.
"Most Alzheimer's disease treatments focus on slowing the symptoms or preventing the disease from progressing, but our research suggests that in the future we may be able to reverse the effects of memory loss, even in patients who have lost brain or neural tissue," said Karen Ashe, professor of neurology and lead author of the study.
The results will be published in the July 15 issue of the journal Science.
In the past, it was generally accepted that dementia was caused by two substances that accumulate in the brain: neurofibrillary tangles, which are tangled bundles of fibers in neurons, and amyloid deposits, a toxic build-up of plaque in the brain. The researchers found that even after the memory loss was regained in the mice, the tangles remained, and even increased in number. This suggests that the tangles are not a cause of dementia as previously thought.
The mice serve as a model that shows how the disease progresses as well as the possibility that memory loss can be reversed. The research suggests that the
Source:University of Minnesota