Thursday October 29, 1998
Adult Brains Can Grow New Cells
By MALCOLM RITTER AP Science Writer
NEW YORK (AP) - Scientists have shown for the first time that adults
grow new brain cells, even in their 60s and 70s.
Up to now, it was generally believed that once you lost brain cells as
an adult, they were gone forever. The finding raises a
distant hope for treating brain diseases or damage by getting the brain
to fix its broken circuitry.
The new neurons, or nerve cells that form circuits, were found in just
one small part of the brain - the hippocampus, a
deep-brain structure that's important for learning and memory. And it's
not yet clear whether the new brain cells actually
function, or what they do.
Still, the discovery contradicts the traditional wisdom that adult human
brains do not make new neurons, even though that ability
had been identified in rat brains some 30 years ago.
``It's not providing an answer or a cure at this point in time for any
particular disorder, but it's a very exciting discovery,'' said
Dr. Ira Black, head of neuroscience and cell biology at the Robert Wood
Johnson Medical School in Piscataway, N.J.
The big question is whether scientists can find ways to make new brain
cells appear in the right places to overcome damage
from strokes, brain injuries and such diseases as PARKINSONS and
Alzheimer's. Right now, for example, the new neurons are in
the wrong place to replace brain cells lost to heavy drinking.
Lots of people think they also lose brain cells just by getting older,
but it's not clear whether that's true.
The new finding is reported in the November issue of the journal Nature
Medicine by Fred Gage of the Salk Institute for
Biological Studies in La Jolla, Calif., and Peter Eriksson and
colleagues at the Sahlgrenska University Hospital in Goteborg,
Sweden.
For the study, they examined autopsy specimens from people who had been
given a drug called BrdU because of cancer in
their mouths or throats. BrdU is taken up by dividing cells; doctors had
administered it to see how rapidly the patients' tumors
were growing.
But the drug also spreads through the body, including the brain. The
researchers reasoned that if cells in the brain were dividing
to spawn new cells, they would take up BrdU, and the substance would be
present in the new cells.
In hippocampus samples from all five patients, the researchers did, in
fact, find neurons containing BrdU.
Two of the patients were in their 50s, two were in their 60s, and one
was 72 when the cells were produced.
The brain makes neurons during its early development, of course, and
``what we're saying is the same programs that are present
during development are persisting throughout life,'' Gage said. ``Things
we thought were ending are not ending, they're just
continuing at a slower rate.''
--
Judith Richards, London, Ontario, Canada
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