In younger people we can see the affect of stress often show up in their reduced ability to process information and it may materialize as lack of focus, depression, ADHD, Dyslexia and similar challenges. In the older generation we can see stress reduce a persons memory, focus and concentration and at its worse manifest as Alzheimer's disease.
Not so long ago the early signs of Alzheimer's disease was typically seen in people over the age of 65, and became more pronounced and more common in people over the age of 85. But the fact that there are many people in their 70's, 80's, 90's and older with excellent memories proves that a degradation in our memories performance is not a natural part of the aging process.
Today many people in their forties and fifties are concerned about the fact that their memory and their ability to concentrate appears to be failing, and their zest for life is almost gone. Although some people still assume that this decline is a natural part of the aging process, fortunately enough people have recognized that this is not natural and thus there must be a cause and therefore a cure or at least a preventative measure that can be taken. Tremendous funds are currently been channeled into research programs designed to understand the way the memory works, and what occurs to produce memory problems and disease's such as Alzheimer's. (If this is an area of interest to you, I highly recommend you read "Brain Longevity" by Dr. Khasla, M.D.)
Research findings reveal that although a certain amount of stress can heighten our memory recall, and encoding, too much stress can cause it to shut down, and on going chronic stress can actually lead to cell degeneration in the hippocampus, our memory processing center, resulting in severe memory degradation.
I will not attempt to give you a lesson here on how our memory works, but I would like to draw your attention to a couple of basic links between stress and it's potential interference with, or damage to our memory system.
Our hippocampus is our main memory processing area within the brain. It serves to handle both our short term memory, and to collate information and when so instructed (if relevant enough or rehearsed enough) to pass this information into our long term memory system. We also use the hippocampus to recall memories from long term storage. The hippocampus, as with many structures in the brain has a left and a right structure. The hippocampus residing in our left hemisphere is thought to handle symbolic digital processing and auditory short-term memory, while the right hippocampus is largely involved with visuospatial processing and visual short term memory. These two parts of the hippocampus are connected via the hippocampal commissure. Thus as with the other parts of the brain residing in the separate brain hemispheres, when we lock into the stress response, locking into our dominant brain hemisphere, we will also loose integration between the right and the left hippocampus. When this line of communication goes down, temporarily, we have the experience of our mind going blank/drawing a blank; for example a nervous person about to make a public address, sees the audience, stresses and their mind goes completely blank. Partial shut down may put us in the common situation of recognizing a face, but forgetting the name - I know I know it, it's on the tip of my tongue… These examples are common with temporary short lived stress. However the long term chronic stress has a much more profound and damaging effect on your hippocampus. Not only will the lack of connectivity interfere with both your memory processing, filing and recall, but recent research has shown that chemicals released as part of the stress response actually kill the brain cells in the hippocampus.
Researchers have for some time recognized that people locked in the stress response for extended periods of time have memory impairment, and degeneration of the hippocampus. Cortisol was thought to be the possible culprit, causing a toxic bath to the brain cells in this area. However new research from the University of California, Irvine, by researchers Brunson and Baram’s proves conclusively that excessive release of the hormone CFR (corticotropin-releasing hormone) will find it's way into the hippocampus (where there are many receptors for CRF) and overtime will kill the cells in this area. Fortunately these cells are renewable. However as with Multiple Sclerosis and other brain problems if the on going cause of the damage is greater than the speed at which the cells can be replaced, degeneration in this area of the brain will result, or scar tissue will develop to interfere with normal processing. Thus if you are locked in the stress response for extended periods of time, causing a continual release of CRF to flood into the hippocampus, it makes sense that it would affect the normal operating environment of our hippocampus. Add this to the confusion caused by the lack of left/right connectivity between the two areas of the hippocampus and you can see how short term stress hampers our memory, and long term stress kills it!