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How to Live Well With Early Alzheimer's
By Deborah Mitchell
St. Martin's PressCopyright © 2010 Lynn Sonberg Book Associates
All rights reserved.
What Is Memory?
Oscar Wilde once said, "Memory is the diary we all carry about with us," and this sentiment presents a familiar, convenient image. But you can't hold a memory, like you can a diary. Nor can you taste it, smell it, see it, or hear it. A touch can, however, be the stimulus that causes a memory to come to your consciousness. The same is true of a smell, a sound, a scene, or a food or beverage. But none of these concepts answers the big questions: What is memory? How does the human brain collect, store, and process memories? Where does memory go when it's "gone"?
Chances are one of the reasons you are holding this book is that these are some of the very questions you are asking yourself, perhaps for yourself or for a loved one who is experiencing memory loss or who has early Alzheimer's disease. It's also very likely that you also want to know what you can do about preventing and preserving memory. But before we can answer any of these and other related questions and concerns, it's helpful to have a basic understanding of how a healthy brain works.
HOW A HEALTHY BRAIN WORKS
The human brain is a three-pound biological wonder. The estimated 100 billion nerve cells (neurons) that populate this soft, grayish-white mass dictate nearly everything you do whether you are conscious of it or not. Thus your brain controls not only the love you feel for your partner but the beating of your heart whenever you see him or her.
The vast amount of research into the causes, prevention, and treatment of Alzheimer's disease and other dementias goes hand-in-hand with the work being done by scientists to explore the extremely complex workings of the brain. Here is some of what we know thus far about the brain and how it works.
The brain loves sugar (glucose), and it needs a constant supply of this food to nourish and energize the constant activity of the billions of neurons. Let's liken this activity to a relay race. The neurons have fibers (called dendrites and axons) that form connections with other nerve cells. When a nerve cell is activated (as when we hear the starting gun at the start of a race), it sends an electrical message (like a baton) along the length of a long fiber called an axon.
When the signal reaches the end of the nerve cell (the handing-off point), brain chemicals called neurotransmitters are released from another type of fiber called dendrites. The neurotransmitters cross the gap between nerve cells (synapses) and attach themselves to receptors on the nerve cell on the other side of the synapse. Nerve cells that accept neurotransmitters (accept the baton from the "runner") then pass the message along to the next nerve cell, and on and on until the signal reaches its end point.
When you keep repeating an action (for example, practicing a tennis serve), you restimulate and reactivate the same nerve cell connections, or synapses, again and again. After you have practiced for some time, the synapses undergo a physical change and become stronger and more efficient at storing the behavior in your long-term memory. The areas of the brain that form the core of the memory-processing center are the hippocampus, the amygdala, and several other structures in the temporal lobe.
The hippocampus lies deep within the brain in the temporal lobe. Experts generally agree that the hippocampus plays a critical role in the formation of new memories of events (episodic memory). It is one of the first areas of the brain to suffer damage in people who have Alzheimer's disease.
The amygdala appears to have an important part in the formation of emotional memory. As you will learn below, emotional memory is very powerful and long-lasting.
WHAT IS MEMORY?
Memory is a brain function that involves the ability to retain information or to recover information about experiences from the past. When we say or think to ourselves, "I remember that!" there is a process that takes place in the brain that involves the recovery and reconstruction of information that we have stored about things we have learned or done.
Types of Memory
Memory can be broken down into three categories: sensory, short-term, and long-term. Sensory memory occurs when you first encounter or perceive an event or object. For example, let's say you are driving in an unfamiliar city and you get lost. The moment you realize you do not know where you are, you are overtaken by a feeling of anxiety and frustration. A sensory memory has just been created.
Short-term memory (also known as working memory) stores information that you need to remember within a short amount of time (minutes to hours). Now that you are lost, you decide you need to stop to ask someone for directions. When you receive the verbal direction, you will need to retrieve the instructions while you maneuver through the streets. This information is short-term memory.
Chances are you won't need to remember the directions again and again, so your memory of them will eventually be replaced by other memories. That is the nature of short-term memories: They are supposed to be fleeting. If they were not, you would not be able to accommodate them. Research shows that the average person is able to retain only about seven (plus or minus two) unrelated pieces of information in the mind at one time. That's why it's easier to remember a seven-digit telephone number or a Social Security number rather than a vehicle identification number or a set of complicated directions on how to break down and reassemble a motor.
Short-term memory also is fragile. Let's return to the driving example. If while you are getting verbal directions your passenger interrupts you by saying, "Do you think we'll make it by two-thirty, because I have an appointment," chances are you will forget some or all of the instructions being given to you. This mental glitch is normal; it is simply the nature of short-term memory. We will be referring to short-term memory often, as this is a type of memory that is lost by people who have Alzheimer's disease. For example, it is typical for individuals in the early stages of Alzheimer's to forget what they had for lunch today, or to forget someone's name shortly after being told what it is.
In long-term memory, your brain stores information that you need to access again and again. In our example, long-term memory is your memory of how to drive. All long-term memory involves permanent, physical changes to the nerve cells and electrical circuitry of the brain. If you have ever wondered why a person who has moderate to severe Alzheimer's has poor or no short-term memory but can remember with clarity events from their childhood or the name of their first love, it is because their long-term memory is intact, "hardwired" into the brain.
Long-term memory can be broken down into three types, or parts:
Episodic memory refers to the ability to recall personal events and experiences from the past. The past can be as recent as yesterday (remembering what you ate for lunch) or a baseball game you saw when you were seven years old. This type of memory organizes information around events (episodes) that occurred in your life. Episodic memory allows us to recall not only events but also information that is associated with those events. So, you may remember the baseball game as well as eating hot dogs and popcorn at the game. People who have early Alzheimer's disease generally have no problems with episodic memory.
Semantic (or declarative) memory includes facts that are so entrenched in your brain that you don't have to exert any effort to recall them. Examples include knowing the days of the week or knowing what a cat is. This type of memory also allows people to understand written words regardless of what type style they are presented in, because the brain understands the concept of a letter rather than a specific example of one. These types of memories are subject to destruction early in Alzheimer's disease.
Procedural memory is the type necessary to perform activities like driving, eating, dancing, and walking. It is the "how" type of long-term memory: the ability to remember how to do something in a series of steps. For driving, for example, those steps can include getting into the car, putting the key into the ignition, turning the key, putting the car into drive, and so on. When we retrieve information from procedural memory, we retrieve one step at a time, and each step then triggers the next step. Procedural memories are more resilient to destruction than are semantic memories in people who have Alzheimer's disease. Therefore, people in the early stages of the disease typically have little or no trouble remembering how to do the ballroom dancing they did for years, or how to make their favorite sandwich. Many people with early Alzheimer's disease even remember how to drive, although their sense of direction and remembering where they are going can be compromised and thus driving is often not safe for them to continue.
You may see different terms for these types of long-term memories, but overall, the consensus is that these various types of long-term memory are related and overlap, although scientists are not exactly sure how they work together.
The differences between short- and long-term memories are not simply how long the memories last. As we mentioned, the brain can only handle a small number of short-term memories at the same time, yet it can store an unlimited number of long-term memories. And unlike short-term memories, which are easily disrupted, long-term memories are not lost if some interrupt your train of thought.
Memories and Emotions
Have you ever wondered why some memories stay clear for years while others fade over time? The answer is emotion, both positive and negative. Research shows that the brain retains many details about events that evoke lots of emotions (e.g., your wedding day, a traumatic car accident). In fact, according to a study done by experts at Duke University, women are more likely than men to report intense emotional experiences and to remember them.
Why does this happen? Two areas of the brain are active during successful retrieval of memories: the amygdala and the hippocampus. These areas of the brain are close to each other and they also successfully encode emotional memories. Therefore memories that have emotional significance for people are better hardwired in the brain and better recalled. So when your Aunt Helen can't remember what she had for lunch today but she can vividly remember the blue dress she wore the day she got her first kiss, you'll know why.
What Do Memories Look Like?
A new study published in June 2009 by investigators at the Montreal Neurological Institute and Hospital, McGill University, and the University of California, Los Angeles states that for the first time, scientists have been able to capture an image that shows what happens when long-term memories are formed. What does long-term memory look like?
The researchers exposed nerve cells to a brain chemical called serotonin, which has been shown to stimulate the formation of memory. They then used a fluorescent protein capable of changing from green to red when it is exposed to ultraviolet light. When they flashed the cells with the light, they noted that any proteins that already existed turned red. But when they stimulated the cells to form memories, they saw new green proteins under the microscope.
Although green fluorescent blips may not be the stuff of which poetry is written, this discovery is considered a breakthrough for memory researchers. Images of long-term memory are formed when new proteins are created at the synapse, which is the connection between nerve cells. When this action takes place, it increases the strength of the synaptic connection and reinforces the memory that has been formed. Neuroscientists now know that protein synthesis is necessary for long-term memory to last. This information may help them develop new ways to prevent and treat memory loss.
Normal Memory Loss
Although it is common to think that memory problems don't begin until people are middle-aged or older, the truth is that brain cells begin to die when individuals are in their twenties. This is also the time when the body makes less of the chemicals the brain cells need to continue their work. Over time, these brain cell changes begin to have an impact on memory. Short-term and remote memories are not usually impacted by the aging process, but recent memory may be affected. Don't become alarmed if you forget the names of people you were introduced to recently: This is part of normal changes in memory. In fact, the more you fret over your inability to recall the names immediately, the more difficult it may be for you to remember. That temporary lapse, however, is the result of stress and not the onset of dementia. In most cases, you will remember the names with time — perhaps minutes, hours, or even a day or two.
When it comes to memory and memory loss, it is not a matter of black and white, but plenty of gray areas in between. Caregivers of people who have Alzheimer's disease will often ask why their loved ones can remember something one day and then forget it the next, and then retrieve it again later. The answer, it seems, lies somewhere in that gray area.
Sometimes, however, memory problems persist and gradually grow worse, significantly affecting daily activities. You or a loved one may have trouble remembering how to do things that once were a habit or getting to a place that you have been to many times in the past. That's when you should stop and evaluate what is going on and ask, Is it Alzheimer's disease or is it something else? That's the question we address in the next chapter.CHAPTER 2
The Many Faces of Memory Loss
When people begin to notice lapses in their memory, too many believe that a diagnosis of Alzheimer's disease will inevitably follow. The truth, however, is that in many cases memory loss is caused by a reversible condition, or it may be attributed to a common condition known as mild cognitive impairment. In other people it is caused by a type of dementia besides Alzheimer's. The point is, if you have trouble remembering your shopping list, if you keep losing your keys, or if you can't remember someone's name, it doesn't necessarily mean the seeds of Alzheimer's disease or dementia have planted themselves in your brain.
In this chapter we explore the main causes of memory loss, namely aging, mild cognitive impairment (MCI), Alzheimer's disease, and other types of dementia, as well as use of medications, depression, alcoholism, medical conditions, and head trauma.
AGE-RELATED MEMORY LAPSE
If you are age 50 or older, you are a member of a population in which about two-thirds of men and women notice memory problems, such as forgetting appointments, having trouble remembering names, and walking into a room and forgetting what they came for. Relax, these are small memory lapses that typically occur with age. These lapses' sometimes referred to as "senior moments"' may be frustrating, but they don't interfere with your ability to do your job, travel, run your household, or perform any of your other activities.
Several factors cause the brain to change in its ability to retrieve and hold onto memories. Along with the loss of neurons with age, older people often experience a decrease in blood flow to the brain. Less oxygen to the brain cells can mean a reduced ability to recall. The hippocampus is also very susceptible to age-related deterioration, and this can affect the ability to retain information.
Overall, age-related forgetfulness is not a loss of memory but a slowing down in the ability to absorb, store, and retrieve information. Thus, it might take you a little longer to recall someone's name or where a certain restaurant is located, but you will. Just be a little patient with yourself. If you begin to worry a lot about your senior moments, the stress itself can affect both memory functioning and mood. That's because the body releases cortisol, a hormone released by the adrenal glands in response to stress. High cortisol levels have a negative impact on memory, even in healthy individuals, and they can even damage the hippocampus.
Many brain functions, however, are barely affected by normal aging. For example, natural aging of the brain does not damage the knowledge and wisdom you've accumulated during your life, as well as your common sense, the ability to form reasonable arguments and judgments, and the ability to learn new skills (although it may take you a little longer to learn them).
At this point in their lives, some people who are experiencing age-related memory glitches take steps to exercise their brains as a precautionary measure against dementia and/or further cognitive deterioration. This is a positive move, and we strongly encourage it. In fact, the activities discussed in chapter 9 may provide you with some suggestions.
Excerpted from How to Live Well With Early Alzheimer's by Deborah Mitchell. Copyright © 2010 Lynn Sonberg Book Associates. Excerpted by permission of St. Martin's Press.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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