The Brain, Memory, and Alzheimer's Disease

What Your Doctor May Not Tell You About(TM) Alzheimer's Disease : The Complete Guide to Preventing, Treating, and Coping with Memory Loss (What Your Doctor May Not Tell You About...(Paperback))
by Deborah Mitchell, Gayatri Devi, M.D.

Perhaps the biggest mystery that faces humankind is not whether there is life on other planets or how the universe began, but exactly how the human brain works. I believe the human brain is the last frontier. What is thought? What is memory? How is memory stored? Where is memory stored? What happens when memory is lost? How does the brain know how to manage this concept we call memory?

You probably had not thought much about these questions until now. But, because you have picked up this book, things have probably changed. Now you want some answers-which we will provide in this chapter-because either you or a loved one is having memory “problems.” Keys are being misplaced, again and again. The names of neighbors are being forgotten. Perhaps bills aren't paid on time or are forgotten altogether. The titles of favorite books can't be recalled. And somewhere in the back of your mind, two words loom, even though they frighten you and you try to push them away:

Alzheimer's disease.
And to that we reply, don't be alarmed. Why?

• Some forgetfulness occurs as a natural part of aging. There is a difference between this age-related forgetfulness and the memory loss associated with Alzheimer's disease and other forms of dementia. I will talk about the differences in the pages ahead.
  
  
• If you are concerned about memory loss, there are things you can do to help prevent it.
  
  
• And, if Alzheimer's disease is diagnosed, there are many ways to make the life of the person who has the disease a loving, rich, and fulfilling one.
  
  

There is much confusion and apprehension surrounding what constitutes “normal” age-related memory loss and changes in brain function and what clues suggest the serious and progressive memory loss that is characteristic of Alzheimer's disease. To help alleviate any anxiety and fears you may have about memory loss and to help you more clearly understand what Alzheimer's disease is, I believe it is important for you to have a basic understanding of the following:

• healthy brain activity and how the brain ages normally;
  
  
• how memory works and what constitutes normal age-related memory loss;
  
  
• the signs and symptoms of Alzheimer's disease and other forms of dementia; and
  
  
• how the normal age-related changes in brain function and memory compare with those associated with Alzheimer's disease.

Perhaps more than any other medical condition, Alzheimer's disease has a profound impact not only on the individuals who have the disease, but on their family, friends, and other significant people in their lives. I believe it is essential that those who are closest to the people who have Alzheimer's understand that the changes in personality and behavior they will witness and experience are the result of physical damage to the brain, and that this damage leads to much frustration, anxiety, and fear on the part of those who have the disease and those who love them.

Individuals who are affected by Alzheimer's are not their disease; they are not Alzheimer's patients-they are people affected by Alzheimer's disease. They are still mother, father, sister, brother, aunt, uncle, grandmother, best friend; they are still individuals capable of loving and sharing; they still need a hug and a smile. So do you. And you'll be better able to give and receive those feelings once you become more familiar with your challenger-the human brain and the changes it can go through during this disease process.

Normal Brain Activity

The human brain is without question the most complex piece of machinery known to humankind. It contains an estimated 100 billion nerve cells that tirelessly communicate and make it possible for you to think, remember, move, perform vital functions, and, overall, experience life. Your brain controls virtually every aspect of your life, from sitting and breathing to your desire to eat or paint, to your empathy for a friend or your joy in seeing a sunset.

Looking Inside a Healthy Brain

Even though the brain is such a complex organ, we are understanding it more and more through research, which is also helping us uncover the mysteries of why memory loss, Alzheimer's disease, and other dementias occur. I believe a basic understanding of how a healthy brain functions can help you better appreciate what happens to people who experience memory loss or dementia. It will also help you understand how the “brain boosters” can benefit you and your loved ones.

The human brain, although weighing in at a mere three and a half pounds, is very much a heavyweight. Nearly half of all the blood pumped from the heart goes directly to the brain, even though this organ accounts for a mere fraction of the entire body weight. A constant supply of sugar (glucose) is produced by the body at all times to keep the brain nourished. Why does the brain need all this energy? The billions of nerve cells are in constant activity, whether you are awake or asleep, constantly producing electrical signals. Thanks to new imaging techniques, activity in areas of the brain as small as a grapeseed or as large as an orange can be measured as various tasks are performed.

Different parts of the brain specialize in different tasks, recruiting other areas as needed to best accomplish a given job. While extremely efficient, this level of subspecialization comes at a price. Destruction of an area important for, say, memory or for math will make it difficult for a person to be able to designate another area of their brain to do the same function. Children have this capacity, as their brains are not yet fully developed, but adults are more restricted. Despite this, adults are capable of a tremendous amount of adaptation or “plasticity,” so there is some measure of this in our older years as well.

The brain is divided into two sides, or hemispheres. The left side deals with language and details and is the more “analytical” or “logical” part of the brain. The right side deals with space and understanding emotions and is the more “artistic” part of the brain. So, the right side sees the forest, while the left side sees the trees. Some people are more “left brained” while others are more “right brained,” yet others are about equal. If you are wondering which side of your brain you tend to use more, try this experiment. Look quickly (for about one second) at the picture below, then look away.

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iiiii
iiiii
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iiiii
iiiii
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What did you see? If you saw the E, you are a right-brainer; if you saw a bunch of little i's, then you are a left-brainer; and if you saw both, you are using both sides of your brain. Within each side of the brain are various lobes. The frontal lobe, the largest area of the brain, is concerned with voluntary movement, language expression, social judgment, personality, problem solving, and abstract thinking in general. The temporal lobe is involved with memory, language comprehension, and perception. Deep within the temporal lobe is a structure called the hippocampus that can be viewed as a gateway for storing and retrieving certain types of memory. The parietal lobe is important for sensation and for understanding spatial relations. The occipital lobe is involved in vision.

In Alzheimer's disease, the earliest changes occur in the hippocampus and then spread to other areas of the brain, especially the temporal and parietal lobes. The hippocampus is a tiny, sea horse-shaped organ that is one of the most sensitive parts of the brain. It is more vulnerable to the effects of reduced oxygen and glucose supply than any other part. It lies near the middle of the brain, one hippocampus on the right side and another on the left. This organ is very important for the “when,” “what,” and “where” memories.

It would be helpful if all the brain's functions and tasks were as neatly compartmentalized into the various regions and lobes I've just identified. In reality, however, that isn't so. Memory, for example, isn't confined to just one area of the brain. When we recover a memory, it is as if we cast a net over the entire brain and pull out aspects of the memory from different parts of the brain to form the whole mosaic of the memory. When you hear a snippet of a song, it activates a part of a memory trace, and the brain then may recall for you who you danced with the first time you heard the song, what you were wearing, what your partner's perfume smelled like, and how their skin felt. Each of these bits of the memory mosaic comes from a different part of the brain.

Storage of memory also occurs in the same fashion. For example, when you see and smell a flower, the messages regarding what you see are active in one part of your brain, while the smell is processed in another, and the sorting and filing of the memory of the flower happen in yet another region.

Brain Talk: How Brain Cells Communicate

Neurons and neurotransmitters are the great communicators in the brain. The 100 billion nerve cells in the brain communicate by producing and sending electrical signals to other cells. Unlike heart cells, no two nerve cells actually communicate by direct contact. Instead, when one neuron is ready to communicate with another neuron, a signal travels along the body and axon (a single branch that extends from the neuron's main body; its job is to carry signals to other neurons). When a message reaches the tip of the axon, it triggers the release of chemicals called neurotransmitters into the synapse, the space between the axon of the sending neuron and a receiving neuron. The neurotransmitters then attach themselves to receptors (docking sites) on the dendrites (receiving arms) of the receiving neuron. Once the neurotransmitters are attached, the process of sending the signals begins again.

In a healthy brain, a message is transmitted from neuron to neuron until it reaches its intended destination, which may be leg muscles, lungs, eyes, or another part of the brain. Nerve cells are sending signals every second of your life: when you see a flower, stub your toe, fall in love, or digest your lunch, signals are flying.

One way to imagine the brain is to think of it as a very intricate orchestra consisting of billions of positions, all under one conductor (you!), but divided into different sections- strings, reeds, and so on. When one area does not function well or is not in sync with the others, then the music is not quite right, the mind isn't quite right, and memory can be affected.

In a healthy brain, nerve cells and neurotransmitters go about their communication function with few or no problems. However, as you'll learn in the next chapter, something interferes with the normal functioning of the neurons and neuro-transmitters in people who have Alzheimer's disease.

The Healthy Aging Brain and Declining Memory

As we age, we expect to feel a few aches and pains and notice graying hair and wrinkles, but these are just the external signs of aging. What about internal changes, particularly in the brain? The passing of the years is accompanied by a normal dying off of nerve cells in the brain. In fact, brain cells begin to die when people are in their twenties, decades before they even think about the possibility of Alzheimer's disease. At the same time, aging is also associated with a decline in the number of synapses (fewer cells means fewer synapses), a decline in the amount of some brain chemicals, and shrinkage of the brain size, often called atrophy. Although we place such a premium on remembering, it is important to realize that the human brain was designed to forget. We have evolved over millennia with forgetfulness programmed into our brain as a normal function so that there will be available space for new memories as old memories are pruned away. In some very rare instances, individuals are unable to forget anything. In these situations the person becomes unable to function as the brain becomes clogged with millions of memory traces.

“Senior Moments”

For the majority of people sixty-five years and older, all of these brain changes work together to result in mild forgetfulness, a slight loss of concentration, and a slower response time when, say, they try to recall a telephone number or someone's birthday. They may occasionally forget what to buy at the grocery store, where they put their keys, or the name of the teller they always see at the bank. And, for this majority, these transient episodes of forgetfulness can be annoying, yet certainly manageable.

Sylvia, a sixty-nine-year-old retired accountant, calls her minor slips of memory “senior moments.” She finds that making simple adjustments, such as always making a shopping list instead of relying on remembering what she needs from the store, or always putting her car keys in a basket by the front door, has reduced her number of senior moments, as well as stressful episodes. She also keeps her mind active by reading and staying socially active as a volunteer in the community.

Memory Loss Is Inevitable but Alzheimer's Is Not

It's important to remember that while all of us will forget more as we get older, loss of memory is not synonymous with Alzheimer's disease or dementia. Many people in their eighties and nineties remain mentally sharp and witty and continue to contribute to society as writers, grandparents, researchers, volunteers, physicians, politicians, and artists. Exactly why some people retain their memories while others do not is still a mystery, but one that researchers and physicians are exploring vigorously.

In fact, contrary to what experts thought for years, recent research is showing us that people can maintain brain plasticity and number of synapses well into their eighties and nineties. This ability doesn't come without some effort, however. Thus the adage “use it or lose it” applies here, and we'll help you do just that in chapter 6, “Brain Boosters: An Exercise Program for Mental Fitness.”

What Is Memory?

How Are Memories Stored?

Each time you remember something, up to three steps may occur. The first step is your perception or registration of the object or event. Let's say you decide to learn French and you have a list of ten vocabulary words. You look at the words and say them out loud, which allows your senses to register the sight and sound of the words. This is a rapid assessment process, which takes less than a second for each sound. You have created a sensory memory.

In step two, you retain the sensory memory. This typically involves thinking about the words, repeating them several times in class or at home. At this point, this sensory memory is “stored” in short-term memory. However, if you drop out of the French class or don't practice the words over and over again, your memory of them will eventually be replaced by other, incoming memories. The vast majority of short-term memories doesn't make it to the third step because they aren't important enough to remember for a longer length of time or they were not consolidated (practiced, reviewed repeatedly in the mind, or in some other way often brought to your attention). Short-term memory is an important concept for people who have Alzheimer's disease, as this is one type of memory that is lost.

In step three, you recall the situation. Not all memories reach this stage. If you stay in your French class, do your homework, and practice speaking French, you will likely remember the words and continue to improve your vocabulary. This memory has been stored in long-term memory. Truly long-term memory is always associated with permanent structural changes in nerve cells and circuitry. It is remarkably resistant to destruction. This is why even people who have advanced Alzheimer's disease, who do not know where they are or the names of family members, will give you their parents' names and sing along to old familiar tunes.

All long-term memory is always associated with physical changes in the brain. Physical changes result when nerve cells sprout to form more branches for more connections to other cells, and from the strengthening or weakening of connections between some nerve cells. This type of preferential connecting allows the formation of a pathway or a network. This allows cells with similar functions to establish strong connections with one another, in, for instance, a visual pathway for sight memories and an auditory pathway for sound memories.

On the Types of Memory

I can't think and hit at the same time.
-Yogi Berra

We can also view memory as procedural or declarative. Declarative memory is the type of memory that most people associate with having a good memory, that is, the ability to recite facts. Declarative memory is the memory of facts and events; people with a good declarative memory are often good at games such as Trivial Pursuit or Jeopardy. This is the kind of memory that is involved in answering “what,” “where,” and “when” questions. Procedural memory is the memory necessary to perform activities like walking, driving, and dancing. It is the answer to a “how” question, as in “How do you walk?” The “when” and “where” answers, which relate to a specific time and place, are far more sensitive to destruction. These memories are affected first in memory disorders.

Constant repetition of an initially declarative memory task such as the multiplication tables or playing the piano makes it a procedural or muscle memory. Think of a skill such as learning to drive. At first, it is a very conscious and describable process, but with repetition it soon becomes automatic and “reflexive.” In the process, the brain converts a fragile memory into something very resistant to destruction. Hence, the old adage of habits first being cobwebs, then cables, is true in neuroscience. The brain lays down strong connections between appropriate regions when a task is repeated over and over again.

Great athletes often have very well-developed procedural memories for golf or shooting baskets, for example. Because a lot of their memory is procedural, it is hard for them to describe their skill and teach it to someone else. They play by “instinct.” This is why it is sometimes hard for champion athletes to become good coaches. The inimitable Yogi Berra noted the difference between these two forms of memory: “I can't think [declarative memory] and hit [procedural 'muscle' memory] at the same time.” By the way, it should come as no surprise that Yogi did not make it as a coach!

Among people who develop Alzheimer's disease, they will first experience destruction of their declarative memory skills, such as what happened when and where (what movie did I see and who was in it), and then the retention of facts (what is the capital of Italy and what is 6 times 6). Very old memories, which occurred when a patient was young, are resistant to destruction. The “when” and “where” memories are destroyed first, the “what” next, and finally the “how” memory is destroyed. Thus persons with abnormal forgetfulness will progress from “When did I last have a sandwich?” and “Where did I put my sandwich?” to “What is a sandwich?” to “How do I eat a sandwich?”

Procedural skills are the most resilient, so that the ability to do whatever it is the person is skilled at, be it cooking or knitting or drafting, is the last to go. In a certain condition called apraxia (an inability to perform purposeful movements), some kinds of manual tasks are affected. In addition to memory changes, in a condition called aphasia, patients will have difficulty with language, although their memory may be intact.

Emotion and Memory

Intense emotions are often associated with unforgettable memories. Thus, neither war experiences nor first kisses are usually forgotten. For such occasions, people often remember the dress they were wearing on the day, what the day was like, about what time of the day it was, what the weather was like, and the surroundings-almost like a snapshot. This is because the part of the brain that controls emotion, a small brain organ called the amygdala, is very closely linked to the hippocampus, which is so important for memory. Various studies have found that memories that have emotional meaning are better laid down in the brain and better retrieved than those that lack emotional significance.

Flashbacks are negative consequences of this emotionally etched memory, where victims of extreme trauma, like war, relive the entire experience in excruciating detail. Seemingly innocuous triggers can set off this emotionally highly sensitive and well-remembered memory trace: a scent in the environment, the color of someone's eyes, the shape of a room, or the sound of a plane passing overhead.

Interestingly, mnemonists, or memory specialists, use emotion to their advantage to remember. One famous mnemonist, studied by the renowned Russian scientist Luria, experienced sensations on his skin, tasted a particular taste, and saw a particular color every time he heard a certain note of music. He consciously made each memory an intense emotional experience and, therefore, unforgettable. Unfortunately, this man became so good at remembering that he had trouble forgetting. This made it impossible for him to function well on a daily basis, until he worked out a method to actively forget. (He needed to write down each memory he needed to forget on a blackboard and erase it!) Thus we can see the value of forgetting.

The Bottom Line

The human brain is an ever-changing, ever-evolving organ that has the capability to acquire and retain new information when it is well into its eighth or ninth decade. It is also the organ of memory, that hard-to-define concept that we depend on every second of every day. What happens when that “friend” begins to slip away from us, not just infrequently but on a daily basis? Could it be something serious? Could it be Alzheimer's disease?

Copyright © 2004 by Gayatri Devi, M.D., and Lynn Sonberg

About the Author

Deborah Mitchell is a medical writer and journalist specializing in complementary medicine and nutrition topics. Her articles have appeared in professional journals, as well as national consumer magazines. She has authored and co-authored eleven books about various health topics, including Natural Healing for Back Pain, The Natural Guide to Headache Relief, The Dictionary of Nutritional Healing, Natural Aphrodisiacs, Natural Medicine for PMS and MSm: The Natural Pain Relief Remedy.

Gayatri Devi, M.D. lives in New York City.