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 darned subunits. 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 person.
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 that way. "These are biological processes, and once we fully understand what is going on, we may be able to slow or prevent it."
In recent research [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. [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] 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. "The one thing that does seem fairly clear is that cognitive decline is not inevitable. 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."