Dr. Roy Murrell, DC 200 NE 20th Avenue, Suite 140 Portland Oregon 97232 - disclaimer - 971-312-9497
ANATOMY OF STRESS PART II: STRESS AND MEMORY
One of the most common things aging baby boomers worry about is declining mental capacity and loss of memory. With the current epidemic of Alzheimer's it is easy to become paranoid with the slightest stumble, like trying to remember where you parked your car at the mall. Doctors say this is common with age and not to worry, at least until you forget that you even own a car. Does stress accelerate this normal aging process? Lets talk a little about the anatomy of memory first.
There are two basic types of memory: Explicit which consist of facts and events and your conscious awareness of knowing them, and Implicit which are skills and habits and our knowledge of how to do things without thinking about them. Explicit memories can become Implicit with time and repetition, like playing an instrument. There are two major parts of the brain that are involved in storage of memories, the cortex (the vast convoluted surface of the brain) and the hippocampus which sits under the cortex. It is these two areas that are most affected by Alzheimer's disease. If you wanted a good metaphor, the cortex would be the hard drive of your computer and the hippocampus would be the keyboard to access the hard drive. Memories are stored on several neurons (nerve cells), not just one. When you are trying to remember someone’s name, you might struggle with it, while being able to remember the color of his hair or facial features, etc. The neuron that stores this information becomes excited and interacts with other neurons which can bring more information to your consciousness and hopefully one of these will be the name you are trying to remember.
Stress and memory are sort of like stress and pain -- a mixed bag. Short-term stressors can actually enhance memory. This makes sense, in that this is the sort of optimal stress that we would call "stimulation" -- alert and focused. This is accomplished by getting the sympathetic nervous system to stimulate the hippocampus into a more alert, activated state, facilitating memory consolidation.
If the stress evolves into a more intense, long-term stress, it will have just the opposite effect. Your memory will decline. This is commonly seen in people that have Cushing's Syndrome, a disease in which patients develop tumors that secrete large amounts of glucocorticoids (the same hormone produced in stress). It has been known for decades that these patients develop serious explicit memory problems that are known as Cushingoid Dementia.
Most of the research around long term stress has been associated with sustained high glucocorticoids and the findings are not good. The Hippocampus seems to be the most affected and these effects can be long term. They consist of decreasing volume or size of the Hippocampus as well as decreasing function. (Remember the Hippocampus is responsible for placing and retrieving information from the cortex.) What concerns scientists the most is the common and frequent use of synthetic glucocorticoids like prednisone or hydrocortisone by the medical community for anti-inflammatory use. The last decade has seen a huge increase in auto-immune inflammatory diseases and these drugs are the first line of defense (and many times, the only defense).
STRESS AND SLEEP
The over-the-counter and prescription drug market for sleep aids is a billion dollar industry. When it comes to sleep and stress, it is a double-edged sword; not getting enough sleep causes stress and stress causes insomnia. It is estimated that 75% of insomnia is related to some sort of stress.
Most people think we need sleep to rest our body but what we really need it for is to rest our brain. The brain comprises only 3% of the body's weight but uses 25% of its energy. All this activity takes a lot of glucose (energy food) and we eventually need to take a break to replenish these energy stores. It is also important for the consolidation and processing of information. Research has shown that sleep deprivation can decrease the level of retention of new information into long-term memory. A recent study of jet lag (a form of sleep deprivation) experienced by flight crews that fly consistent over-seas flights through multiple time zones showed a significant decrease in memory and cognitive skills and even a smaller temporal lobe of the brain compared with flight crews that did not fly these routes.
The most important part of this double-edged sword is the effect of stress on how we sleep. Even the smallest thing like knowing you have to get up early for an important engagement can make you sleep restlessly. How many times have you set your alarm for something and then wake up several times in the night thinking it is time to get up? What is even worse is chronic stress causing chronic insomnia. You go to bed knowing or believing that you are not going to sleep which causes a stress response that then fulfills your prediction, perpetuating the chronic insomnia.
Medications can help you break this cycle but are seldom recommended as a long-term solution. This is a complicated issue but the first thing you should look at is identifying the source of your stress. If you can't eliminate it, at least try to decrease its effects on you by putting it into a different context (like putting whatever positive spin on it you can). Second on my list would be to get more exercise (especially cardiovascular). This usually sounds terrible when you are sleep deprived but trust me, it will be immensely helpful. Next would be to stay away from processed foods high in additives and sugar; they only increase your stress levels. There are many natural foods and herbs that have a calming effect on us, so do some research and find those you like. Stay away from stressful television before bed or anything that gets your pulse going (except maybe doing the wild thing with your partner). Unfortunately for some, none of this will help and they will continue to rely on medication and struggle with sleep deprivation.
STRESS, SEX, AND REPRODUCTION
Libido and sexual performance are two things most people take for granted until they are not there. It takes a lot to slow down the average guy's libido but as we age erections are a different story. It is estimated that about half of all visits to a doctor complaining about erectile dysfunction are related to psychogenic causes, most of which are stress related. The whole process of erection is a very complicated dance between hormones controlled by the brain via the sympathetic and parasympathetic nervous systems with a great deal of help from the vascular system. An over active adrenal gland pumping out glucocorticoid stress hormones can throw a monkey wrench into the picture quickly. There can be numerous causes but the most common are hormonal imbalances and a sluggish nervous system (which could be related to your spine so see your Chiropractor).
On the flip side of this equation, women are much more complicated. There are a number of things that can inhibit the monthly cycle and the success of reproduction as well as a healthy libido. Again, it would be too much to get into the details, but the cascade of releasing hormones that start in the brain and travel to the ovaries where they stimulate estrogen production are inhibited by glucocorticoids. One other thing that can interfere is the hormone prolactin that is produced during breast feeding but is also secreted during stress. (This is the reason it is somewhat of a birth control during breast feeding but not one you want to count on.) Endorphins produced during exercise can also be a complication. It is common for extreme athletes to stop having normal periods due to a lack of estrogen production from the ovaries.
Despite all of this, in most cases, it takes a lot more than mild stress to interfere with one of life's most basic human reflexes. On the other hand, we have all known someone who finally makes that monumental decision to have a baby and then becomes despondent when she does not get pregnant in the first month or two of trying. After months of trying and copious amounts of stress, she resigns to the fact it is not going to happen and boom: she gets pregnant.
STRESS AND DEPRESSION
It is estimated that between 5 and 20 percent of us will experience a major, incapacitating depression at some point in our lives. No one really knows what causes depression but the accepted premise relates to some sort of disorder of the brain neurotransmitters. There are three primary neurotransmitters, norepinephrine, serotonin, and dopamine. Their function is to transmit data through the synaptic junction from one nerve cell to the next after which they are recycled back into the nerve cell to be reused later. Current anti-depression drugs prevent this recycling and therefore create an increased number of these transmitters to flood the synaptic space. Most of the current drugs target serotonin, better known as SSRI’s (Selective Serotonin Re-uptake Inhibitors). They really don't know exactly why these help; they just know that some depression responds to these drugs, at least for a period of time.
How and where does stress fit into this equation? This can run in two directions. Most people who have depression are prone to abnormal stress responses and frequently (but not always) have high glucocorticoid levels. On the flip side, those who are experiencing chronic stress, especially around issues of loss of control or loss of a social support system, tend to get depressed. It has also been known for years that patients prescribed ongoing doses of synthetic glucocorticoids for inflammatory diseases can become clinically depressed. It has also been shown that stress hormones can alter all three of the neurotransmitter systems in the way of decreased synthesis, how fast they are broken down, how many receptors there are for each neurotransmitter, how well they work, and so on. Again, there is a lot that is not known but it is safe to say that stress and depression commonly have a symbiotic relationship.
By now, you have read that stress affects almost every system of the body. It can play havoc with your digestive system, raise your blood pressure, interfere with your sleep, ruin your sex life and possibly damage your brain. It’s enough to make you depressed just reading about it. Stress has a cumulative effect and really, this is all about how fast we age. There are so many things that affect aging and it starts in childhood. Animals studies show that the more stress a child has, the more glucocorticoids he/she will secrete as an adult in response to stressful events. This often is influenced by socio-economic status, stability of the family dynamics, nutrition, exercise, healthy relationships and a host of other factors.
As adults, there are many obvious things that reduce stress: working at a job you love, having a loving relationship, putting energy into a good social network of friends, and two of my favorites, nutrition and exercise. Bad food is a stress all of its own and accounts for a vast majority of the chronic illness in our aging population. Exercise is as important as food, or at least a close second, and the best stress reducer is cardiovascular exercise. It has a vast array of benefits from better circulation, lower blood pressure, better digestion, and better sleep, to those great things called endorphins that make you feel good. It is also very helpful for mild to moderate depression. All that being said, it has to be something you like doing which is the difficult part for some people who just hate any form of exercise. If you are not the cardio type, try Yoga, Tai Chi, or meditation; they are all very helpful.
It is a new year and the start of a new decade so make it a point to be aware of your stress and do what you can to reduce it when possible. You might just live longer and more importantly, healthfully.
Yours in Health,