Alzheimer's, Dementia & Mental Health
Cognitive decline with age
is normal, routine – but not inevitable
Research making it clear cognitive decline with age
is natural part of life, scientists tracking the problem down to highly
specific components of the brain
By David Stauth
Aug. 7, 2013 – If you forget where you put your car
keys and you can’t seem to remember things as well as you used to, the
problem may well be with the GluN2B subunits in your NMDA receptors. And
don’t be surprised if by tomorrow you can’t remember the name of those
They help you remember things, but you’ve been losing
them almost since the day you were born, and it’s only going to get
worse. An old adult may have only half as many of them as a younger
Research on these biochemical processes in the
Linus Pauling Institute at Oregon State University is making it clear
that cognitive decline with age is a natural part of life, and
scientists are tracking the problem down to highly specific components
of the brain. Separate from some more serious problems like dementia and
Alzheimer’s disease, virtually everyone loses memory-making and
cognitive abilities as they age. The process is well under way by the
age of 40 and picks up speed after that.
But of considerable interest: It may not have to be
“These are biological processes, and once we fully
understand what is going on, we may be able to slow or prevent it,” said
Kathy Magnusson, a neuroscientist in the OSU Department of Biomedical
Sciences, College of Veterinary Medicine, and professor in the Linus
Pauling Institute. “There may be ways to influence it with diet, health
habits, continued mental activity or even drugs.”
The processes are complex. In a study just
published in the Journal of Neuroscience, researchers found that one
protein that stabilizes receptors in a young animal – a good thing
conducive to learning and memory – can have just the opposite effect if
there’s too much of it in an older animal.
But complexity aside, progress is being made. In
recent research, supported by the National Institutes of Health, OSU
scientists used a genetic therapy in laboratory mice, in which a virus
helped carry complementary DNA into appropriate cells and restored some
GluN2B subunits. Tests showed that it helped mice improve their memory
and cognitive ability.
The NMDA receptor has been known of for decades,
Magnusson said. It plays a role in memory and learning but isn’t active
all the time – it takes a fairly strong stimulus of some type to turn it
on and allow you to remember something. The routine of getting dressed
in the morning is ignored and quickly lost to the fog of time, but the
day you had an auto accident earns a permanent etching in your memory.
Within the NMDA receptor are various subunits, and
Magnusson said that research keeps pointing back to the GluN2B subunit
as one of the most important. Infants and children have lots of them,
and as a result are like a sponge in soaking up memories and learning
new things. But they gradually dwindle in number with age, and it also
appears the ones that are left work less efficiently.
“You can still learn new things and make new
memories when you are older, but it’s not as easy,” Magnusson said.
“Fewer messages get through, fewer connections get made, and your brain
has to work harder.”
Until more specific help is available, she said,
some of the best advice for maintaining cognitive function is to keep
using your brain. Break old habits, do things different ways. Get
physical exercise, maintain a good diet and ensure social interaction.
Such activities help keep these “subunits” active and functioning.
Gene therapy such as that already used in mice
would probably be a last choice for humans, rather than a first option,
Magnusson said. Dietary or drug options would be explored first.
“The one thing that does seem fairly clear is that
cognitive decline is not inevitable,” she said. “It’s biological, we’re
finding out why it happens, and it appears there are ways we might be
able to slow or stop it, perhaps repair the NMDA receptors. If we can
determine how to do that without harm, we will.”
About the Linus Pauling
Institute: The Linus Pauling Institute at OSU,
Corvallis, Oregon, is a world leader in the study of micronutrients and
their role in promoting optimum health or preventing and treating
disease. Major areas of research include heart disease, cancer, aging
and neurodegenerative disease.
This research was supported by grant number AG16322
of the National Institutes of Health.