A 鈥淢EMORY PILL鈥� could one day restore old people鈥檚 ability to learn and
recall things, say researchers in Britain. They think they have found out why
our memories can fail as we get older.
A brain structure called the hippocampus is known to play a key role in
learning and memory. Many scientists think it is changes in the strength of
connections between neurons in the hippocampus that make our memories fail. But
others have suggested that changes in the way these cells fire are to blame.
After a nerve cell fires, it takes a little while to recover before it can
fire again. In hippocampal cells, the recovery period gets longer as we age.
Could this be why learning and memory falter in old age?
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An international team led by Karl Peter Giese of the Wolfson Institute of
Biomedical Research at University College London set about finding out. They
created genetically engineered mice that couldn鈥檛 make a protein called Kv&bgr;1.1.
This protein influences the activity of potassium ion channels in the membranes
of neurons鈥攚ithout it, hippocampal neurons recover faster after they have
fired.
When Giese tested these elderly mutant mice in a water maze, he found they
did just as well in learning and memory tasks as normal young mice, he told a
conference in Glasgow earlier this month organised by the Institute of
Nanotechnology.
In the past, researchers have improved the learning abilities of mice by
targeting other ion channels鈥攂ut these changes make both young and old
mice smarter. Crucially, Giese found that his young mutant mice actually had
learning problems鈥攐nce they had learned something, they struggled to cope
with change鈥攕uggesting that the slowed recovery rate of hippocampal
neurons really is responsible for memory failure as we age.
The team is now trying to develop drugs that mimic the effects of the genetic
mutation. But Giese warns it could be a decade before such a pill is
available.
鈥淭he question now is whether or not there are influences on neurons
throughout the brain,鈥� says Ira Black of Rutgers University in New Jersey. To
avoid side effects, he says the ideal drug would only affect the hippocampus.
Indeed, Giese told the conference that the effects of the mutation seem to be
largely confined to the hippocampus, affecting only parts of the striatum and
cortex.
Such a pill might restore the learning capacity an old person had in their
youth, although it couldn鈥檛 give them back lost memories. However, because
Giese鈥檚 young mutant mice had learning difficulties, perhaps the drugs could be
used only to treat the loss of mental abilities, rather than to prevent it in
the first place.
The researchers have submitted their results for publication.