So is this the reason for your memory problems rather than your stroke? Or is your doctor enamored with Occams razor?
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From telephone numbers to foreign vocabulary, our brains hold a
seemingly endless supply of information. However, as we are getting
older, our ability to learn and remember new things declines. A team of
scientists around Associate Prof Dr Antonio Del Sol Mesa from the
Luxembourg Centre for Systems Biomedicine of the University of
Luxembourg and Dr Ronald van Kesteren of the VU University Amsterdam
have identified the molecular mechanisms of this cognitive decline using
latest high-throughput proteomics and statistical methods.
The results were published this week in the prestigious scientific
journal “Molecular and Cellular Proteomics”
(doi:.10.1074/mcp.M113.032086).
Brain cells undergo chemical and structural changes, when information
is written into our memory or recalled afterwards. Particularly, the
number and the strength of connections between nerve cells, the
so-called synapses, changes. To investigate why learning becomes more
difficult even during healthy ageing, the scientists looked at the
molecular composition of brain connections in healthy mice of 20 to 100
weeks of age. This corresponds to a period from puberty until retirement
in humans. "Amazingly, there was only one group of four proteins of the
so-called extracellular matrix which increased strongly with age. The
rest stayed more or less the same," says Prof Dr Antonio del Sol Mesa
from the Luxembourg Centre for Systems Biomedicine.
The extracellular matrix is a mesh right at the connections between
brain cells. A healthy amount of these proteins ensures a balance
between stability and flexibility of synapses and is vital for learning
and memory. "An increase of these proteins with age makes the
connections between brain cells more rigid which lowers their ability to
adapt to new situations. Learning gets difficult, memory slows down,"
Dr Ronald van Kesteren of the VU University Amsterdam elaborates.
In addition, the researchers not only looked at the individual
molecules but also analysed the whole picture using a systems biology
approach. Here they described the interplay between molecules as
networks that together tightly control the amount of individual
molecules and their interactions. “A healthy network keeps all molecules
in the right level for proper functioning. In older mice we found,
however, that the overall molecular composition is more variable
compared to younger animals. This shows that the network is losing its
control and can be more easily disturbed when we age,” Prof Dr Antonio
del Sol Mesa explains. According to the researchers this makes the brain
more susceptible to diseases.
Hence, this insight into the normal aging process could also help in
the future to better understand complex neurodegenerative diseases such
as Alzheimer's and Parkinson's disease. Chemical compounds that modulate
the extracellular matrix might be promising new treatments for learning
disorders and memory loss.
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