One of the most frustrating things about Alzheimer’s disease is the inability to diagnose it early. As it stands today, a diagnosis of Alzheimer’s disease is based largely on interviews with the person and his or her family. Circumstantial evidence of behaviors, memory and language patterns, and family medical history lead to a diagnosis. However, a new study led by USC neuropsychologist Duke Han, PhD, associate professor of family medicine (clinical scholar) at the Keck School of Medicine of the University of Southern California suggests that cognitive tests are also able to detect early Alzheimer’s in people who have not yet developed symptoms.
Scientists know that Alzheimer’s disease begins to damage the brain a long time before the symptoms become pronounced enough to warrant a doctor’s visit or testing. Groups of protein clusters, called Amyloid plaques, and tangles of protein grow in the brain and impair its function. Some imaging can detect Amyloid plaques, but that imaging is incredibly expensive, invasive and not easily or widely available. As a result, the only definitive diagnosis of Alzheimer’s disease can be made only after death when physicians can examine the brain.
However, the new USC study showed that people with amyloid plaques performed worse on tests of memory, language, attention, working memory and other cognitive tasks than people who did not have them. This is the first study to show that there is “a perceivable difference in how people with preclinical Alzheimer’s disease perform on cognitive tests,” said Dr. Han. If cognitive tests can detect the existence of early Alzheimer’s disease, that is a game changer for treatment.
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The study’s findings could lead to changes in best practices in annual check-ups for seniors. If this type of cognitive testing is included in annual physicals, then theoretically the onset of Alzheimer’s disease could be detected at a much earlier stage. This would lead to earlier treatment to slow the progression of the disease. Dr. Han says that a baseline read of people’s cognition in their 50’s or 60’s would be invaluable in diagnosing Alzheimer’s disease later on. “Then it could be used as a way to track whether someone is experiencing a true decline in cognition in the future.”
“While there’s no cure for Alzheimer’s disease, the earlier you know that you’re at risk for developing it, the more you can potentially do to help stave off that diagnosis in the future,” Han says. “For example, exercise, cognitive activity and social activity have been shown to improve brain health.”
Detecting Alzheimer’s disease in its earliest stages would impact millions of Americans. The Alzheimer’s Association estimates that five million people in the U.S. have Alzheimer’s disease and that the number could reach 16 million people by the year 2050. According to the Alzheimer’s Association, the direct costs “American society of caring for those with Alzheimer’s and other dementias will total an estimated $259 billion in 2017. A recent study found that in the last five years of life, the costs of a person with dementia, on average, total more than $287,000 (in 2010 dollars).”
If new tests can be developed for the early detection of Alzheimer’s disease, then treatment can begin earlier, reducing the health care costs for everyone. As medications and treatments are developed and applied earlier, the progression of the disease could be slowed, benefiting patients and families.