October 27, 2005

Experimental drug promising for Alzheimer’s

By Megan Rauscher

NEW YORK (Reuters Health) - Bryostatin, a drug that has
been studied as an anti-cancer 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

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

"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.