Read an Excerpt
Note: The Figures, Tables and/or Test mentioned in this chapter do not appear on the web.
Evaluate Your Memory
A good storyteller is a person who has a good memory,
and hopes other people haven't.
IRVIN S. COBB, AMERICAN HUMORIST
Woody Allen once said that the brain was his second favorite organ. While the brain may indeed be the number two choice for many of us, it is by far our most important organ, and memory is one of its most critical functions.
In this part of the book, you will learn how to assess your memory and determine whether it is normal or abnormal. You will also learn about the basic processes underlying memory formation and retrieval in the brain, and how aging affects these processes. This information will help you fully understand the reasoning behind the different elements in the Memory Program.
Some of us forget names; others cannot recall places they've been to before. Our ability to associate names, faces, and places in the context of time helps us to reinforce our memories. Lost memories that suddenly resurface indicate that our brains store much more information than we are aware of in everyday life. Sigmund Freud was convinced that the root cause of "forgetting" is an unconscious conflict that creates a mental block when we consciously try to remember.
While this theory may apply to some people, as we grow older there is a different type of memory loss that affects most of us. This memory loss is a direct result of the aging process.
Benign versus Malignant Memory Loss
In the 1960s, V. A. Kral, a Canadian physician, coined the term "benign senescent forgetfulness" to describe the mild memory loss that he observed in older people, which he distinguished from the more malignant memory loss that is an early sign of dementia. Kral's terminology has been replaced by "age-associated memory impairment" (AAMI) and "age-related cognitive decline" (ARCD). Cognition is a word used to describe a wide range of intellectual functions, including memory. The term "mild cognitive impairment" (MCI) defines a broad group of people who have cognitive deficits and fall between the categories of "normal" and "dementia." Although the original "benign senescent forgetfulness" is rapidly disappearing from the field, it is still useful to recognize that memory loss during aging is often "benign," because it does not worsen markedly over time, especially if sound preventive measures are employed. My patient David Finestone was a case in point: he adopted a systematic program that improved his memory and overall level of functioning.
I have always tended to forget the names of people when I am introduced to them for the first time. I am sure that many of the people I met were convinced that I forgot their names because I didn't really care one way or another. In some cases this was true. But even when I do make a conscious effort to remember a name, I often cannot retain it unless it is repeated back to me. Even more embarrassing is when I meet someone who crossed my path some months or years ago and I discover that I am absolutely clueless about that person's name. I wouldn't be surprised if some of you have had similar experiences, though hopefully not as often as I've had.
Before I started studying memory loss, I preferred to forget this personal flaw. However, at the back of my mind was the memory of how my mother used to constantly joke about my late father's inability to remember names. I grew up in Calcutta, India, and my father would regularly call Mr. Chatterjee by the name of Mr. Banerjee while Mr. Ghosh became Mr. Das. My father gave a few unfortunate souls four or five names on different occasions. In striking contrast, my mother always had a razor sharp recall for names. This facility only doubled her amusement at my father's gaffes, which often led to his laughing at himself. But observing these patterns in my family led me to wonder: is the ability to recall names mainly genetic? If so, I would have a great excuse for my shoddy recall of names, though blaming my father's genes for this deficit does sound like a lame excuse.
Forgetting names is a widespread, almost universal, phenomenon. Some of you may agree with my self-serving explanation that there is a strong genetic component. However, forgetting names is not in itself a clinical syndrome, and few researchers have exerted much time or energy to get to the root of this problem, genetic or otherwise. There has been one remarkable exception: Albert DaMasio, a neurologist who is a giant in his field.
The Tip-of-the-Tongue Phenomenon
In a compelling paper published in the journal Nature, DaMasio and his colleagues showed that the areas of the brain that encode and store memories of proper nouns are distinct from those responsible for other kinds of nouns, even though these regions are physically very close to one another and are near the hippocampus, which forms part of the temporal lobe in the brain. His work has taught us a great deal about how different elements of memory are stored and helps explain the tip-of-the-tongue phenomenon. If memories for different types of words are stored in different groups of nerve cells, these nerve cells need to communicate with one another to produce a composite memory of the entire object or person that is rich in detail. If this communication does not occur, you may recall one element of the memory but not another, and the missing component remains on the tip of the tongue. This process of retrieval is not entirely conscious, because the "missing link" may suddenly resurface when your mind is preoccupied with something else, which somehow gives the nerve cells a better opportunity to communicate.
Symptoms of Memory Loss
Many other symptoms of memory loss are not as benign as forgetting names and are listed on the following page. If you (or someone close to you) have signs of severe memory loss, or if you've developed functional changes associated with memory loss, you should get your symptoms investigated by a doctor. The most important warning sign is a clear-cut worsening in memory compared to how you were a few months or years ago. Early, Usually Benign, Signs of Memory Loss
Signs of Severe Memory Loss
- Forgetting names
- Forgetting a few items on a shopping list
- Misplacing keys, wallets, handbags
- Forgetting to turn off the stove once
- Losing your way in a giant mall
- Not recognizing someone you met a long time ago
Functional Changes Associated with Severe Memory Loss
- Getting lost in a familiar place
- Losing your way when driving a familiar route
- Forgetting important appointments repeatedly
- Forgetting to turn off the stove on several occasions
- Repeating the same questions over and over again
- Difficulty in understanding words or in speaking fluently
- Not knowing the date or time
- Problems at work; coworkers say that your poor memory is causing too many mistakes
- Making many errors in balancing a checkbook or writing checks
- Difficulty in naming common objects or finding words
- Apathy, irritability, and other personality changes accompanying memory loss
Seeing Your Doctor for Memory Loss
Any one of the following categories of professionals can evaluate memory loss:
- PRIMARY CARE PHYSICIANS (internists, family practitioners) can identify the medical causes of memory loss (e. g., hormonal abnormality or medication toxicity), but they often miss the early signs of subtle to mild memory loss because most are not very skilled at testing for it.
- NEUROLOGISTS are physicians trained in the diagnosis and evaluation of neurological disorders such as stroke and multiple sclerosis. They are generally good at identifying early signs of memory loss. However, only some neurologists have developed expertise in diagnosing and treating memory disorders.
- PSYCHIATRISTS have a medical degree and specialize in the treatment of mental disorders. They are excellent at identifying causes such as depression underlying memory loss. However, like most neurologists, most psychiatrists are not skilled at diagnosing and treating memory disorders.
- NEUROPSYCHOLOGISTS have a Ph. D. and not a medical degree. They are expert at administering tests of cognitive function, including memory, and interpreting the test results as normal or abnormal. They usually work in collaboration with a primary care physician, neurologist, or psychiatrist.
Where to Go for Help
Some doctors still advise their patients not to worry, that memory loss is just part of growing old and can't be helped. Clearly, they have not kept up with the latest developments that show how memory loss can be reversed or at least slowed down.
If you have severe memory loss then you should see a doctor. In our specialty center, neurologists, psychiatrists, and neuropsychologists work closely together, using a team approach. Until the average physician gets better at recognizing the types and causes of memory loss, your best option is to go to one of these specialized academic medical centers that employs a team approach. There are now a large number of these centers serving virtually every major urban, and even semiurban, area in the United States (listed in the appendix). If you do not have ready access to one of these centers, consult a neurologist or psychiatrist, or your primary care physician. Inquire if they have experience in diagnosing and treating memory loss and dementia.
If you have no memory loss, or mild memory loss not due to a specific reversible cause, you probably do not need to consult any physician and can go ahead with learning about and implementing the Memory Program in this book. But to identify exactly where you stand on the spectrum of memory loss, you need to take the following memory tests and see how well you perform on them.
Other Tests of Memory
The Selective Reminding Test is a complex list-learning test that starts in a simple way: the tester recites a list of twelve unrelated words and then asks the subject to recite all twelve words together. Then comes the tricky part: the tester prompts the subject with only those words that the subject missed on the first repetition, following which the subject is again required to repeat all twelve words, that is, recite the words that were missed the first time as well as those that were "kept in memory" from the first to the second trial. This sequence continues until the subject either gets all twelve words correct in successive repetitions or a total of twelve trials is completed. In the delayed recall part, the subject is challenged fifteen minutes after the last trial to recall the entire list of twelve words. The large number of trials requires complex scoring procedures and neuropsychological expertise. The Visual Reproduction subtest of the Wechsler Memory Scale is a different type of test because it evaluates the ability to remember shapes (recalling visual images).
Each test taps into a slightly different aspect of memory. A neu-ropsychologist typically administers a whole range of tests and looks for consistent patterns of deficits. If the subject performs well in all except one test, it may be due to a lapse in concentration. On the other hand, if someone scores consistently below normal on several memory tests, further investigation is necessary.
Factors That Affect
Your Memory Test Performance
Three well-recognized factors can influence performance on memory tests: age, education, and gender.
Since it is "normal" for memory test scores to worsen as people grow older, the standard test scores are adjusted downward to get the "norms" for that age group. Therefore, a "normal" ninety-year-old person may actually score worse on the standardized memory tests than a fifty-year-old person with moderate memory loss.
These age-adjusted test scores are used to help distinguish a clinical disorder from normal test performance within a particular age group. The flip side, of course, is the risk of dismissing worsening memory as "normal" for a person's age and doing nothing about it.
People who are highly educated score much better on neuropsychological tests than people with low levels of education. You may recall that when my patient Frieda Kohlberg, who had a genius-level IQ, developed only very subtle memory deficits and otherwise tested at or above the normal range for someone her age, it was actually the first sign of Alzheimer's disease. But compared to other tests of intelligence and cognitive ability, memory is less affected by the subject's educational background.
You may be wondering about the third leg of the triad: age, education, and gender. In fact, there are subtle differences: women score slightly better on tests of verbal memory, and men score slightly better on tests of nonverbal memory (unusual shapes and diagrams that cannot be "coded" verbally for recall) and mathematical ability. However, these differences are very small and may result more from bias during the educational process than from a true genetic influence.
If You Get Neuropsychological Testing
If you get neuropsychological testing, you should find out from the neuropsychologist if the actual raw scores were used to make the interpretation or if they were adjusted for age and other factors. If you do well with or without age and education adjustments, your mental faculties are in excellent condition. If you need such adjustments to raise you into the normal range for people at your age and education level, then you probably have subtle age-related memory loss. If you score poorly, whether age and education adjustments are made, your memory loss is severe enough that you should go see a physician (if you haven't already). Action Steps to Evaluate Your Memory
- Subjectively, is your memory worsening over time based on your own perception? Do others say that your memory is worsening?
- Use the lists in this chapter to check if you have symptoms of mild or severe memory loss, and if you have functional impairment due to memory loss.
- Identify your strengths and weaknesses, separating them into the verbal and nonverbal (spatial, 3-D) memory categories, based on the Subjective Memory Questionnaire.
- Have someone give you the memory tests in this chapter. Classify yourself according to the post-test instructions into one of three categories: no memory loss, subtle to mild memory loss, severe memory loss.
- If your memory has worsened considerably over time, or if you have symptoms of severe memory loss, or if you scored very poorly on the memory tests, you should consult a neurologist or psychiatrist, preferably with the input of a neuropsychologist. If you have access, go to the memory disorders clinic at your local major academic medical center.
- If your memory has not worsened considerably over time and you do not have severe symptoms and you scored well on the memory tests, or if you have only minimal to mild deficits on the memory tests, medical consultation is not essential. In essence, if you have no memory loss or mild memory loss, you should read further to understand and implement the Memory Program in your daily life.
Imaging Your Brain to Diagnose Memory Loss
While neuropsychological testing is critical to define the extent of memory loss, brain imaging is often more helpful in identifying the type of brain abnormality that may be causing the memory loss. Brain imaging techniques broadly fall into two categories: structural (CT and MRI) and functional (SPECT and positron-emission tomography, or PET).
Structural brain imaging techniques are used to evaluate the structure, or anatomy, of the brain. Computerized axial tomography (CAT or CT) was the first such technique. Strangely enough, it was invented in the 1970s by researchers at EMI, a British music recording company that couldn't capitalize on it, although they did get the Nobel Prize for their invention. CT scanners take a large number of X rays in different planes and use computer technology to "reconstruct" the internal brain structure, which then becomes crystal clear to the viewer.
MRI works on a different principle. A strong magnetic field is applied around the head, and the distance traveled by individual protons (subatomic particles) in response to the magnetic field is measured in various parts of the brain. The MRI's computers use this information to produce clear, fine-grained images of internal brain structures. Unlike CT, MRI involves no radiation exposure. In any case, the risk of damage from radiation is low for the brain because it has few dividing or reproducing cells, making DNA damage unlikely.
Claustrophobia can develop in the MRI machine, which makes a loud banging noise. "Open" MRI is a method recently developed for people who have claustrophobia, but because it is open (the head is only partially enclosed) the magnetic field used is weaker and the sensitivity of the technique is much lower than that of a regular MRI.
Both SPECT and PET involve the intravenous injection of a radioactive tracer that is taken up by the brain. A combination of high-resolution cameras and sophisticated computers produces a 3-D image of radioactive tracer counts, representing blood flow or glucose metabolism (consumption), throughout the brain. SPECT or PET can reveal subtle deficits in blood flow or glucose consumption that have not led to changes in brain structure the subject may still have a normal MRI. The first patient described in the introduction, David Finestone, had a subtle blood flow deficit on SPECT in the presence of a normal MRI, and this information proved very useful in his clinical management.
Brain Imaging to Diagnose Early Alzheimer's Disease
Recent studies show that a reduction in size of the hippocampus (which can be detected by using MRI) and a reduction in temporal and parietal lobe blood flow (SPECT) and glucose metabolism (PET) are often early diagnostic features of Alzheimer's disease. However, using MRI to assess the hippocampus requires sophisticated, labor-intensive research techniques (visual inspection isn't good enough).Also, these abnormalities detected by MRI and SPECT/ PET can occur as part of normal aging and in other neurologic disorders. Although none of these techniques are diagnostic by themselves, they can help when the clinical picture is unclear.
Functional MRI is a new technique that involves looking at changes in hemoglobin oxygen saturation (indicates brain tissue oxygen use), usually while the subject is performing a test of attention or memory. Functional MRI is in its infancy but may well become the wave of the future. A major problem is that its results are worthless if people cannot keep their heads completely still while they lie in the scanner.
The decision about which brain imaging technique to use remains in the hands of your physician. Nonetheless, if you have memory loss, knowing the basics outlined here will make you a more informed consumer about the role of these brain imaging procedures in diagnosing the cause of your memory loss.