The very good news is that a key blood factor declines as a result of
aging that if supplemented, should improve brain function among the
aged. It sounds like it may be readily identified and brought into
therapy.
Many other avenues are now been explored but this one promises to be
quick of the mark the moment we identify the key molecule(s). We can
be optimistic and it is also likely something we already know a lot
about. Blood chemistry declines with age and we know that. Just
restoring what we know may just be good enough. It may even be bone
simple.
I would like to see this solved quickly. The elderly are far too
often rendered intractable as they are overwhelmed by age. Yet we
know it is possible to live to the century mark and be witty. Need I
recall George Burns and Bob Hope? Both were able to function at
almost one hundred percent until the switch was flicked. That is
good enough.
Young blood really
is the key to youth
18 October 2012
by Helen Thomson
HUMANS are constantly
searching for an elixir of youth - could it be that an infusion of
young blood holds the key?
This seems to be true
for mice, at least. According to research presented this week at the
Society for Neuroscience conference in New Orleans, Louisiana, giving
young blood to old mice can reverse some of the effects of
age-related cognitive decline.
Last year, Saul
Villeda, then at Stanford University in California, and colleagues
showed they could boost the growth of new cells in the brains of old
mice by giving them a blood infusion from young mice (Nature,
doi.org/c9jwvm).
"We know that
blood has this huge effect on brain cells, but we didn't know if its
effects extended beyond cell regeneration," he says.
Now the team has
tested for changes in cognition by linking the circulatory systems of
young and old mice. Once the blood of each conjoined mouse had fully
mixed with the other, the researchers analysed their brains.
Tissue from the
hippocampus of old mice given young blood showed changes in the
expression of 200 to 300 genes, particularly in those involved in
synaptic plasticity, which underpins learning and memory. They also
found changes in some proteins involved in nerve growth.
The infusion of young
blood also boosted the number and strength of neuronal connections
in an area of the brain where new cells do not grow. This didn't
happen when old mice received old blood.
To find out whether
these changes improved cognition, the team gave 12 old mice eight
intravenous shots of blood plasma either from a young or an old
mouse, over the course of one month. They used plasma rather than
whole blood to exclude any effect produced by blood cells.
The mice then took
part in a standard memory task to locate a hidden platform in water.
The old mice that had received young blood plasma remembered where to
find the platform much quicker than the mice on the old plasma.
To find out which
brain area was involved in this reversal of cognitive decline, the
team performed fear conditioning tests. Mice that had been given
young blood were better at remembering fear associated with tasks
that activated the hippocampus, suggesting that young blood has a
specific effect on this area of the brain.
But the mystery
remains: what exactly is it about young blood that old blood doesn't
have? "We have not identified any individual factors responsible
for the rejuvenating effects of young plasma yet," says Tony
Wyss-Coray, also at Stanford. His team is now trying to identify
possible candidates such as lipids and hormones.
Villeda is hopeful the
results might one day translate to humans since the components of
blood that change with age in mice mirror those in humans.
While "it's
plausible that similar mechanisms operate in humans," says
Joseph Quinn at Oregon Health and Science University in Portland,
there is no evidence yet to support this.
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