Feeling frazzled from stress and wondering why you’re so scatterbrained these days?
Well stress and memory are more linked than you may realize and though you may think you can learn to live with high daily stress levels, your brain doesn’t really ever get used to it - as is demonstrated by how significantly stress can mess with your memory.
Maybe it’s time to slow down and learn to relax? Is what’s stressing you out worth risking your memories over? Because though chronic stress can lead to problems with memory formation and retrieval today (where did I put those car keys!) the long term consequences of elevated neural stress hormones can be scary and irreversible, like brain shrinkage in areas of the brain linked to memory and accelerated age related memory loss.
How Chronic Stress Damages Your Memory
While sudden moments of stress can focus your memory (which is why people who go through traumatic experiences sometimes remember everything in too much detail) in general, high stress levels work against the formation and the retrieval of memories. And when you think about why this is, it makes a lot of sense.
For memory formation to occur you need to:
- Pay attention to something and encode a piece of information as a potential memory
- Consolidate that bit of encoded memory so that it makes it into longer term memory storage (beyond the very short confines of the working memory)
- Be able to retrieve that bit of encoded information as a memory at a later date
All of these processes require mental energy, any of these processes can be derailed by stress and if any one of the three steps of memory get derailed – the memory won’t work.
When you’re stressed about something you focus a lot of mental energy at the source of your stress. So if you're stressed about a meeting you just had with your boss you may be replaying the meeting in your head and using up a lot of your potential attention on your internal thought processes.
Encoding Problems - Now imagine you get a phone call from your spouse who gives you a shopping list of items to pick up on the way home. Although you hear the list as it is said to you, your attention is so diverted onto the focus of your stress that you don’t even encode the information as something to be remembered. You might not even remember a need to stop at all on the way home!
Consolidation Problems - Or maybe you do manage to focus on the list for a moment and think you’ve got it, but as soon as you hang up the phone, instead of rethinking about the items you need to pick up, you go right back to stressing about work and that list never gets consolidated into a long term memory. (One main way we consolidate an encoded memory is through repetition…eggs, butter and cheese…eggs, butter and cheese…). On the way home you remember that you’re supposed to buy something, but you have no idea what!
Recall Problems – Even if you manage to stay focused on encoding and on consolidating a memory, stress can still derail things at the last stage, as you try to recall your encoded information. So imagine you’ve got the list in your head and you head into the store and as soon as walk in you see the person you just had a difficult meeting with at work. This spikes your stress level and your attention is once again very diverted to the source of your stress – and you find that when you try to remember what you came in to buy, you can no longer retrieve your memory.
So your brain only has a finite amount of attention to focus. When stressed, you focus a great deal of your attention on the source of your stress. When you fail to focus your attention on the encoding or consolidation of a memory, it can derail the process – just as stress can also derail the ability to access a memory.
If you are under a chronic state of stress, your mind is never able to focus as completely as it should on memory processes, and so chronic stress diminishes your ability to remember.
The Neuroscience of Stress Related Memory Impairment
Chronic stress causes increased levels of the stress hormone cortisol in the brain and cortisol interferes with the normal functioning of neurotransmitters involved in memory processes.
- In the short term, stress causes a spike in cortisol that interferes with memory processes for a couple of hours
- And in the long term, chronically elevated cortisol levels (from chronic stress) are actually toxic to brain cells and can result in shrinkage in areas of the brain essential to memory processes
So chronic stress causes both immediate memory impairment and the potential for lasting damage down the road…
Researchers can observe this cortisol effect in animal model experiments. In one experiment, rats that had been trained to find their way through a maze were given an electric shock (a stressful event) and then tested on their ability to recall the path through.
- When tested 2 minutes after the shock the rats had no problem finding the path through
- When tested 4 hours after getting shocked the rats had no problems remembering the path
- But when tested 30 minutes after the shock the rats couldn’t remember the way out of the maze
This memory deficit is explained by the rise and fall of cortisol levels in the brain following a stressful event.
Cortisol levels do not rise for a few minutes after the event
Cortisol levels rise after a few minutes and stay elevated for as long as a couple of hours
By 4 hours after the stressful event cortisol levels have returned to normal
When cortisol levels rise memory is impaired. Before and after this rise, memory is unaffected.1
The Stress Hormone Degenerative Cascade – Once It Starts It’s Hard to Stop
Your chronic stress may be giving you memory problems today – but if you’re smart, you’ll reign in some of that stress now before it has a chance to do lasting and permanent damage.
High levels of chronic stress can cause memory problems in people at any age, but for older people, especially people who have been stressed for a long time, stress levels can lead to a downward spiral of memory-related brain damage called the degenerative cascade.
Here’s what happens:
- Chronically stress increases cortisol levels in the brain.
- The hippocampus is the area of the brain which is largely responsible for memory formation and retrieval. The hippocampus is also the area of the brain which controls cortisol levels and which signals for a reduction in cortisol secretions after these levels reach a certain elevated point.
- High cortisol levels are neuro-toxic and cause brain cell death in the hippocampus. Prolonged elevated cortisol levels (such as from years of chronic stress) can lead to a significant shrinkage of the hippocampus and a decreased ability for the hippocampus to regulate cortisol levels.
- In time, after years of cortisol damage, the hippocampus is less able to effectively monitor and signal for a reduction in elevated cortisol levels (it can no longer close the feedback loop) and so stress can cause high cortisol levels that stay elevated and do accelerated and continuing damage to the memory areas of the brain.2
Once reached, this stage of ongoing damage (called the degenerative cascade) is very difficult to arrest.
How to Improve Your Memory
If chronic stress affects your memory you might logically want to take steps to reduce your stress level – but beyond this, you can also improve you memory through conscious effort.
To counter the negative effects of stress on your memory, try:
- Focusing – Stress derails memory by diverting much of your mental focus away from what you need to remember. You can counter this by consciously focusing your attention on any task at hand, one task at a time. If you’re talking with someone on the phone, for example, resist the urge to check emails at the same time, as you may find that by the end of the conversation you’ve missed something important.
- Using Mnemonic Tricks – By associating information with easily remembered songs or acronyms you strengthen the encoding and ease the retrieval.
- Repetition – Nothing fancy here ( we all do it when trying to remember a phone number) but mentally repeating information to be remembered increases the odds it’ll get encoded into longer term memory storage.
- Visualization – Tying a memory to more than one form of sensory perception strengthens the encoding and ease of retrieval. If you need to remember a shopping list, visualize each of the ingredients on it, and to further help things along. imagine what each will feel like in your hands and what each will taste like.
- Association – If you can relate new information to
information you already have in your memory banks you strengthen the encoding process. So, for example, if you are trying
to remember instructions on how to repair your broken bicycle, associate each
of the steps with something you know well, such as steps of car repair. 3
Page last updated Jul 10, 2012