Diagnosing Amnesia

In July 2007 a woman wandered the streets of Dallas, Texas, with no destination in mind. She was not familiar with Dallas. In fact, she had no idea how she even got to Dallas. Perhaps she was visiting family or friends. It was also possible that she lived in Dallas. But the woman had no idea where she lived, or even who she was.

Police officers who investigated the situation said the woman was in good health. She simply had no memory. An officer from the Terrell Police Department told CBS News it was the first time he had ever been asked to identify someone with amnesia who just did not know where she was at all.

Situations like this are rare. Most people who have amnesia, or at least their family members, are aware of how they got it in the first place—on the playing field, perhaps, or in a car accident, or, like FBI agent John E. Douglas, after an illness. When a person such as the woman in Dallas is discovered, he or she is usually taken to a hospital in the hope that doctors can unlock the person’s memories or at least determine what happened to block them in the first place.

The first step is a general examination. If the person is running a fever, the amnesia could be caused by a brain infection. If the person shows signs of a head injury, such as large pupils in the eyes, this may be what caused the amnesia. Doctors also ask questions to determine how well a person’s brain and memory seem to be working as well as what kind of memory loss might be present: retrograde or anteretrograde, depending on whether the person is forgetting old memories or brand-new ones.

“When checking for attention or anteretrograde amnesia,” says author and doctor Robert C. Cantu, “useful tests are repeating four words immediately and two minutes later, repeating five numbers forward and especially backward, and repeating the months of the year backward.”⁴¹

Tests like these are often used in situations when amnesia is suspected and there is a need to find out immediately. When a football player suffers a blow to the head during a game, for example, team doctors ask the player certain kinds of questions to test memory. If the player cannot answer them, then he probably has a serious brain injury.

There are better tests to sort out the amount of brain damage and memory loss a person might have suffered. As scientists learn more about how and where the human brain creates and stores memories, they are able to come up with specific kinds of questions that give them clues about what parts of the brain might not be working. These tests take longer than the word-repeat tests a team doctor might use on the playing field, but they also give doctors a more precise picture of what is happening in the brain.

The Wisconsin Card Sorting Test

Since the late 1940s, doctors have been using the Wisconsin Card Sorting Test, or WCST, to see how well a patient’s brain is working. The WCST can be used in many situations, and it is one of the common tests a person with amnesia is asked to perform. During the WCST, a doctor places four cards on a table. Each card has a different number of colored shapes on it. The first card, for example, might have one yellow triangle. The second might have two blue squares, and the third might have three red circles. The fourth card might show four green diamonds. The patient is then given a stack of cards that also have colored shapes on them. The task is to compare these cards to the four on the table and sort them into rows.

How the patient does this tells the doctor a lot about how the brain is working. The patient might choose a logical reason for sorting the cards, such as placing the cards in rows by color or placing all pictures of squares in one row and all pictures of circles in another. Many sorting options are possible, but the doctor decides ahead of time on one “correct” way to sort— say, by the number of shapes on the card. As the patient places each new card into a row, the doctor says whether the choice is right or wrong. Most people whose brains work normally, even very young children, can soon figure out the correct way to sort the cards.

“If the subject fails to correctly match the cards according to the unstated guidelines, they must be able to alter their sorting strategy,” says Shaheen Emmanuel Lakhan in an article in the Journal of Medicine. “Throughout the WCST procedure, the subject is not informed of the reasoning behind the . . . ‘right’ or ‘wrong’ feedback.”⁴²

Doctors examine the process a person uses to arrange the cards and how long it takes him to discover the “right” way to sort them. This information gives doctors some clues about how certain parts of the patient’s brain are working.

Language Tests

The ability to use words and language is one of the brain’s most important and complicated jobs. Knowing what an object is and being able to describe it in words is simple for someone who has not suffered brain damage, but the process of learning new words and remembering old ones is actually very complicated. A person who has amnesia may not be able to do this very easily. How well a patient uses language, therefore, gives doctors a good idea of how serious memory loss might be.

Physicians Mark Kritchevsky, Judy Chang, and Larry R. Squire describe one patient who came to a San Diego, California, emergency room with a headache and no memory of his name or his past. The last thing he could remember was hitch- hiking in some bushes. He had very noticeable problems with language.

“The patient said that he saw the numbers but did not know their names,” say Kritchevsky and his colleagues. “He could not name a pen and said that, ‘It’s to write with.’ He could not name a shoe and said that, ‘It’s to walk on.’ He could not name a watch.”⁴³ This man’s situation is a good example of how amnesia often causes trouble for a person who is trying to think of words.

Doctors have come up with two good tests of a person’s language ability that give a better picture of what parts of the brain have been damaged and how severe a person’s memory loss might be. The first test is called the Phonemic Verbal Fluency Test. It is similar to the board game Scattergories: The patient is asked to say or write as many words as she can think of that start with a certain letter. As anyone who has played Scattergories knows, this can take quite a bit of thought, and it depends on certain parts of the brain more than others. A person who struggles with this test will give doctors clues about what part of the brain might have been damaged.

The second language test is called the Stroop Color Word Interference Test. In this test, a person is shown cards with the names of colors on them, printed in black ink. First, the patient reads the words on the cards: for example, blue, red, and green. In the next step of the test, the person is shown cards of different colors and is asked to name the color of each card. In the third step, the patient is shown cards with the names of colors on them, but the words themselves are printed in a different color. For example, a card might have the word red written on it, but in green ink. The patient is asked to name the color of the ink, not the word written on the card.

“In the third task,” says Lakhan, “the normal tendency to read the words, rather than the color of the ink in which the words are printed, elicits a significant slowing in reaction time (the time it takes to name the correct color).”⁴⁴

Patients who have a long reaction time, or who cannot name the correct color at all but can only read the word, usually have

Take the Stroop Test

How would you do on the Stroop Color Word Interference Test? Try this. Gather felt pens in three different colors of ink: blue, green, and red. On a sheet of white paper, write the words blue, green, and red, but in a different color of ink. For instance, write blue in red ink, then green in blue ink. Fill the paper with a row of such words. Then, go through the list, saying the color of each word instead of the word itself: If the word red is written in green ink, say green, not red. It is harder than it seems. For patients who have had a brain injury, it may be impossible.

This test is often used on people who are climbing Mount Everest, to determine whether the altitude and lack of oxygen are affecting their brains.

damage in the front part of the brain. This also means they may have problems with memory.

A Need to See the Brain

Language tests and card-sorting tests have been very useful to help doctors discover what parts of a person’s brain are not working properly, but these tests may do more to satisfy a scientist’s curiosity than to help a patient. Just knowing what parts of the brain have suffered the most damage does nothing to cure the patient’s amnesia or bring back memories that have disappeared. These tests also do nothing to help doctors see where or how extensive the damage is.

In the 1940s and 1950s, the time period when the Wisconsin Card Sorting Test was invented and when amnesic HM was recovering from his memory-robbing surgery, doctors had no good way to see what was actually happening to a person’s brain except by actually cutting into the skull to take a look. Given the risk of complications, the thought of brain surgery is, for most people who have amnesia, more frightening than the memory problems themselves. Brains affected by diseases such as Alzheimer’s are best studied after the person has died, when the brain can be removed during an autopsy and examined more closely.

Things are changing, however. Scientists still may not know everything about the brain, but they have come up with brilliant new ways to study it in living patients—without cutting open the skull at all.

The Human Brain, in Pictures

Most great inventions happen by accident, and this was the case in 1895, when a German physicist named Wilhelm Conrad Röntgen happened upon a form of radiation that could make images of the bones underneath the skin of his wife’s hand. Röntgen did not know what to call the beams of radiation that did this, so he settled on the letter X, to stand for “unknown.” The name X-ray stuck, and it has been one of the most important medical breakthroughs in all of human history.

X-ray technology has led to many discoveries and has countless uses in medicine. Cracks in broken bones are identified and repaired, bullets from gunshot wounds are found and removed, and cancerous growths are discovered—all through the use of X-rays. Radiation technology makes it possible to do something for which all patients are thankful: Doctors can see what is happening inside the body without having to cut into it.

“Prior to the x-ray, a physician was able to employ only four of the five senses (hearing, smelling, touching, and tasting) in detecting an illness and its causes,” say Meyer Friedman and Gerald W. Friedland, authors of Medicine’s 10 Greatest Discoveries. “Roentgen’s discovery allowed the doctor to employ the fifth sense (seeing)—not only for detecting, but often enough for curing a disease.”⁴⁵

Nowhere is this more important than the brain. Surgery on this part of the body is extremely difficult. The brain is so well protected that just getting to it is a challenge, and once the brain tissue is exposed, any wrong move by the surgeon could change the patient’s life forever.

With the invention of three important types of technology, all of which evolved from X-rays, modern doctors can take very clear pictures of all parts of the brain. They can see where a blood clot has formed in a patient who has had a stroke. They can find swollen areas in a patient with a brain infection. They can examine the damage done by clumping proteins in Alzheimer’s disease, and they can see whether new medications for this disease are working. They can also “see” thought processes happening in the brain and find the holes in the pathways of electrical signals that might be causing gaps in memory.

Computed Tomography

X-ray technology has come a long way from the simple, black-and-white pictures doctors use to see if a bone is broken. Computers and X-ray machines now work together to create computed tomography scans, also known as CT or CAT scans, of any part of the body, including soft tissues in the abdomen and the head.

Drilling for Memories

In the 1940s and 1950s, before there were ways to look at a brain without breaching the skull, about forty thousand lobotomies were performed on patients in the United States. A lobotomy, or surgery on one or more lobes of the brain, was thought to help people with psychiatric disorders. The process was not always surgically safe. Some doctors even used crude drills to perform a lobotomy. Often, the goal was to make aggressive or difficult patients more cooperative, but it usually had the opposite effect. As doctors and patients soon found out, removing or damaging parts of the brain this way can lead to loss of emotions, hostile and rude behavior in social situations, and of course, the loss of memory.

Before CT scans, X-ray pictures were single films showing bones as white areas, soft tissues such as muscles and skin as gray areas, and air as black areas. CT scanning takes similar pictures, but many more of them, to get a better look at an entire part of the body. The pictures of a kidney, for instance, show slices of the organ, almost like cutting a loaf of bread. Separately, each slice shows not only the surface of the kidney but what is beneath it. When the slices are put back together, you see the entire organ again.

CT scanning of the head works much the same way, taking pictures of the skull and brain in slices. A computer then puts the pictures together like a puzzle, so doctors can see a full and detailed picture of the brain, both outside and in. CT scanning of the head helps doctors to find and diagnose many brain problems that might be causing amnesia: Tumors will show up on a CT scan, as will skull fractures and bleeding in the brain if a patient has had a head injury. Blood clots or broken blood vessels that cause strokes can be found quickly on a CT scan, as well. It is a fast, painless way for doctors to find out what might be wiping out a person’s memories.

“The CT scan revolutionized neurological diagnosis,” say Arthur and Mitchell Bard, authors of The Complete Idiot’sGuide to Understanding the Brain. “The CT scan eliminated the need for drilling exploratory burr holes in the skill.”⁴⁶

Most CT scans of the brain take about twenty minutes. The machine that takes the pictures is called a CT scanner and is shaped like a large donut. The amnesia patient lies on a table, and the table slowly slides through the hole in the center of the machine while pictures are taken.

New CT machines can spin the body around as they take pictures, and this is called a spiral CT. Doctors like these machines because a spiral CT can make three-dimensional pictures of the inside of the body, giving an even better look at brain tissue. Patients like spiral CT machines because they are faster than the older models, so patients do not have to lie perfectly still for quite as long while the machine takes pictures.

Computed tomography is very useful, but it has disadvantages. It exposes patients to radiation, for one thing, so it carries a small risk of causing cancer. CT scans are also a bit better at showing hard tissue, such as the bones of the skull, than showing the details of soft tissue, such as the brain. Doctors working with amnesia patients often use another, newer kind of technology, one that uses magnets instead of X-rays to get a better look at what is beneath the skull.

Magnetic Resonance Imaging

Magnetic resonance imaging, or MRI, takes pictures of the body using magnetic forces. MRI technology provides extremely clear pictures of any type of tissue a doctor wants to look at, even blood flowing in a vein or artery (and perhaps causing memory-blocking damage in the head). MRI scans are used to diagnose many types of diseases, but they are especially useful for looking at the brain.

“An MRI is not bound by the same constrictions as a CT scan,” say Richard C. Senelick, Peter W. Rossi, and Karla Dougherty, authors of Living with Stroke: A Guide for Families. “It can take pictures of the brain past any skeletal structures; it can depict extraordinary details of specific, minute areas within the brain.”⁴⁷

Using magnets to take pictures is very complicated, but like the memory processes it helps to study, MRI technology depends on electrical currents. The body is made up of billions of atoms, the building blocks of cells. Atoms, especially hydrogen atoms, have tiny electrical charges. Magnetic resonance uses a giant magnet to “spin” these hydrogen atoms, and electrical charges make them line up differently under magnetic forces. Computers are able to read the way the atoms line up and translate the information into pictures of a specific part of the body.

An amnesic patient whose doctor requests an MRI lies on a table, which slides into a long tube. The machine takes pictures of the patient’s brain in very thin slices, much like a CT scan. But a CT scan can only take slices from front to back, the way a loaf of bread is sliced. An MRI can take slices in any direction: top to bottom, side to side, even on a diagonal. The “loaves” themselves might look funny this way, but when a computer puts the slices back together, the full image of the brain is clear. So clear, in fact, that it is like looking at the actual brain.

“An MRI can select a point inside the human body and essentially ask it to identify its tissue type,” says Tom Philbin in The 100 Greatest Inventions of All Time: A Ranking Past to Present. The MRI, he says, can “‘look’ at the soft tissues of the body. The brain, spinal cord, and nerves in particular are seen much more clearly with an MRI.”⁴⁸

MRI technology is still quite new, but it is the best method doctors have for looking at the kinds of brain problems that cause amnesia. Most importantly, MRI images of the brain can even be taken while a patient looks at a certain type of picture or does other tasks. These images can help doctors see what parts of the brain are working at different times and what parts are not. With technology such as this, scientists are able to learn much more about how the brain works and the particular parts of it that cause amnesia. Someday, this might make surgical repair of the brain possible to reconnect an amnesiac’s memory.

Electroencephalogram

Seeing the activity of a working brain depends on reading the electrical pulses that neurons are constantly sending back and forth, even when we are asleep. Brain cells talk to each other by way of electrical charges. Therefore, it is possible to measure the electrical activity in the brain to figure out what parts are communicating and what is not working properly. An electroencephalogram, or EEG, is a test doctors use to eavesdrop on what brain cells are telling each other. The “gram” part of the process is a sheet of paper with wavy lines on it, showing doctors the pattern of the electrical activity that is happening in the brain.

During an EEG, flat, metal discs called electrodes are stuck all over the patient’s scalp. Each of these electrodes has a wire that connects it to the recording machine, which draws the lines of the graph. The electrodes look and feel strange, but the process is not painful. They pick up the signals that are jumping around deep beneath the skull.

EEGs can help doctors see how brain cells are communicating and how the brain is responding to senses such as sight and hearing. The graph may seem like nothing but a series of wiggly lines to the untrained eye, but brain specialists can use it to learn more about all kinds of brain conditions, even attention deficit disorder (ADD), sleeping problems, and hallucinations (when the patient “sees” things that are not there). EEGs are also used for patients who are in a coma to see if there is still any activity going on in the brain. The EEG may be one of the keys to unlocking some of the mysteries surrounding memory loss.

Paired with other tests such as CT scans and MRIs, EEGs provide important clues about what is happening inside a person’s brain to cause memory problems. As these kinds of technology evolve and become more sensitive and detailed than ever before, they give hope to thousands of people who live with memory loss. One day, there may be a way to “recharge” a sick or injured brain and dig up memories that have been buried. For now, however, there still is no cure for amnesia. People with the condition can only take part in imaging tests such as CT and MRI scans and hope to make history as part of a future cure for memory problems.