Experimental Drug Seen Promising Fro Alzheimer's

NEW YORK (Reuters Health) - Bryostatin, a drug that has been studied as an anticancer agent, enhances long-term memory in lab experiments, scientists report.

"Bryostatin is a promising treatment for Alzheimer's disease, both for the neurodegeneration -- the underlying cause of the disease -- and for the symptoms," Dr. Daniel L. Alkon, from Blanchette Rockefeller Neurosciences Institute in Rockville, Maryland said in a telephone interview with Reuters Health.

In a previous study in mice, Alkon's team observed that bryostatin effectively stops the Alzheimer's disease process. It reduces brain levels of amyloid-beta protein -- characteristic of the disease -- helps prevent premature death, and improves behavior.

Bryostatin has also been shown to enhance learning and memory retention of rats in a maze task, according to the team's report in the Proceedings of the National Academy of Sciences.

"Now we've taken this drug and explored in great detail how it may affect memory itself -- not just neurodegeneration," Alkon said.

To do this the researchers used the snail-like creature Hermissenda, a biomedical model for learning and memory. Specifically, Alkon and colleagues found that putting bryostatin in the water days before the start of learning sessions led to the synthesis of proteins "necessary and sufficient for subsequent long-term memory formation."

In cultured neurons, bryostatin increased overall protein synthesis by up to 60 percent for more than 3 days.

"What our study shows is that bryostatin can induce the neurons to make these proteins days in advance," Alkon said, "and it takes a training trial or two that ordinarily would produce memory for a few minutes and turns it into something that lasts for weeks. That was totally unexpected."

He added, "The beauty of this drug is that it has already been used in people for years to treat cancer -- although not successfully -- and therefore we know it is nontoxic."

In addition to Alzheimer's disease, bryostatin may also have a role in other dementias, Alkon said, "and maybe even for treating people who need cognitive enhancement such as perhaps people with memory or learning compromise or those recovering from stroke."

SOURCE: PNAS Early Online Edition, October 24, 2005.