Eye-tracking tests may help diagnose Alzheimer's disease

Q: I've heard there's finally a test for Alzheimer's disease, and that it has to do with your eyes. What is it, and how does it work?

A: Although researchers continue their search for a single and definitive diagnostic test for Alzheimer's disease, they haven't reached that goal at this time. However, they continue to make advances in the field, including recent studies that suggest impaired eye movement may be a predictive symptom in some cases.

We don't yet have a cure for Alzheimer's disease, but early intervention has been linked to better outcomes for patients, including an improved quality of life. That makes any developments that aid in diagnosis important.

As most of you probably know, Alzheimer's is a progressive disease. Physical changes that occur within the brain gradually result in cognitive impairment and dementia. Although Alzheimer's disease is most often seen in older adults, it is not considered a normal part of aging. Symptoms include a decline in memory, thinking, speech, judgment, concentration and the ability to carry out tasks. The disease also results in changes to mood and personality.

Other types of dementia and cognitive impairment share many of the same symptoms, which makes early diagnosis more challenging. A diagnosis of Alzheimer's involves a range of screening processes, including a neurological exam, tests to assess cognition and mental status, genetic testing and brain imaging scans. For some patients in the early stages of the disease, watchful waiting is a necessary - and sometimes frustrating - part of the process.

The study you're asking about looks into impaired eye movement as a diagnostic tool in at-risk patients. Participants with two different types of cognitive impairment were assigned visual tasks on a computer screen. For example, they were asked to look at the left side of the screen whenever a flashing icon appears on the right side. A device that can measure 500 eye movements per second then analyzed how well each person completed the task. The researchers found the visual behavior of each group was unique enough that they could differentiate between the two types of dementia just by the results of the tests.

Even more promising was the fact that the eye movement pattern in one type of dementia, where people struggled to look at the correct side of the screen, was similar to those with an Alzheimer's diagnosis.

The take-away here is that eye tracking shows potential for predicting whether someone with mild cognitive impairment is likely to progress to Alzheimer's disease. That means instead of waiting for advancing symptoms, more patients could begin treatment earlier than is now possible.

Without a cure for Alzheimer's, patients rely on therapies developed to prolong and increase independence and improve quality of life. These include memory training, mental stimulation, social integration and physical exercise programs. Cognitive therapies, such as puzzles, simple number and arithmetic problems and memory exercises, have also been shown to have a benefit. These are all most successful before Alzheimer's disease has progressed too far, which makes early diagnosis all the more important.

Q: My wife just had her yearly checkup, and when her blood test results came back, she was told she had recently suffered a heart attack. How can that be, because she never had any symptoms?

A: Your wife had what is known as a "silent" heart attack. Just as the name suggests, it's a heart attack that occurs without the person realizing it is happening. In many cases, though, it turns out the episode wasn't all that silent after all.

It's true that the person didn't experience the numb left arm or sudden chest pain that we all recognize from movies and television, often referred to as the "Hollywood" heart attack. However, upon review, many people will realize they were aware of different, subtler symptoms that signaled a heart attack was taking place.

A heart attack occurs when something causes the flow of blood to the heart to become blocked. Without the oxygen and nutrients supplied by a network of blood vessels known as the coronary arteries, the heart muscle begins to die. This causes an array of symptoms. The most commonly known symptoms of heart attack include pain and pressure in the chest, and pain or discomfort in one or both arms. Additional symptoms include pain or discomfort in the neck, jaw, back or stomach; nausea, lightheadedness, dizziness, shortness of breath, sudden sweating and fatigue. These can be so mild, brief or even innocuous that the person never connects them to a heart attack.

Studies suggest silent heart attacks are more common in women than in men. Women are also more likely to experience symptoms that are unrelated to chest pain. People who have had a silent heart attack may later recall feeling dizzy or short of breath, having a bout of stomach pain or nausea, or experiencing a neck ache or unusual fatigue. These symptoms are easy to attribute to other causes, such as a case of the flu, stress, indigestion or a strained muscle. However, as in your wife's case, blood tests will reveal elevated levels of a protein known as troponin T or troponin I. These are released into the blood when the heart muscle is damaged.

The risk factors for any type of heart attack are the same. These include a prior heart attack, a family history of heart disease, using tobacco products, high blood pressure, high blood cholesterol, being overweight, poor diet and lack of exercise. Age and race also play a role.

After someone has had a heart attack, they can make lifestyle changes to lower risk. These include quitting smoking, reaching and maintaining a healthy weight, adopting a healthful diet; managing chronic health conditions, such as diabetes; and becoming physically active. If appropriate, medications to control high blood pressure and high blood cholesterol will be prescribed.

If anyone has the symptoms of a silent heart attack, it's important not to ignore them. Early treatment will not only lessen the amount of damage that is done to the heart, it may well save your life.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.