Before We Forget...

In the coming decades, an exploding population of people with Alzheimer's disease will overwhelm the U.S. health care system. But finding ways to identify those at risk might stem the crisis. Forgotten names, misplaced keys, and words that lurk on the tip of the tongue: Although these temporary memory lapses rarely signal anything serious, they can mark the onset of Alzheimer's disease. The illness strikes 10% of those age 65 or older, and nearly half of people over 85--and by the year 2050, the number of Americans with the disorder will nearly triple, jumping to 13.2 million, according to Denis Evans, co-director of the Rush Institute for Healthy Aging in Chicago. Alzheimer's could bankrupt the United States health care enterprise in the coming decades, says Jennie Ward Robinson, director of medical and scientific affairs at the Alzheimer's Association. "Our system is not equipped to deal with the demands of caring for so many people who require 24-hour care," she says. The ability to recognize Alzheimer's disease early--before it causes serious harm--could alleviate the stress on the health care infrastructure, and researchers are pursuing tests to predict who might be at risk. Currently, physicians can diagnose Alzheimer's disease with reasonable accuracy by looking for its signature symptoms: a steady decline in memory, increasing confusion, and growing problems with language and decision-making skills. Unlike normal age-related memory slips, Alzheimer's symptoms progressively worsen and come with a battery of behavioral changes such as psychosis, belligerence, aggression, and sleep disorders. By the time these symptoms appear, however, the disease has already done significant damage. "Clearly what we would like to be able to do is take older people with normal cognitive function and look at their brains and determine who is at risk so that when we have drugs that can help prevent Alzheimer's, we know who to give them to," says Neil Buckholtz, chief of the Dementias of Aging Branch of the National Institute on Aging in Bethesda, Maryland. Alzheimer's disease progressively destroys neurons in the brain. In particular, the disease whittles away regions that are associated with cognition, emotion, memory, and spatial ability. It leaves behind hallmark masses of tangled proteins that can be seen under a microscope--but only after the person dies. Now researchers are working to exploit the telltale damage that Alzheimer's inflicts on the brain to develop methods for detecting these changes in their early stages. Using such tests, physicians might even be able to sniff out the disease before people become symptomatic, says Buckholtz. "Even a delay of 1 to 2 years could be dramatic from a public health perspective," says Claudia Kawas, a neurologist at the Institute for Brain Aging and Dementia at the University of California, Irvine. Some researchers have used a technique called magnetic resonance imaging to measure the hippocampus, an area of the brain that helps orchestrate learning and memory and is known to atrophy in Alzheimer's patients. They found that in a group of people with mild cognitive impairment, the individuals who were most likely to develop Alzheimer's disease were the ones with the smallest hippocampuses. The results suggest that in people who are experiencing cognitive problems, an undersized hippocampus might provide an early warning of impending disease. Changes begin even earlier in a region of the brain called the entorhinal cortex, an area near the hippocampus that also contributes to memory. A study published in 2001 examined brain activity of healthy elderly adults using a combination of imaging techniques. The volunteers who showed the least activity in the entorhinal cortex were most likely to experience cognitive decline during the course of the 3-year study. Researchers hope to transform findings such as these into diagnostic tests that could detect brain changes in healthy people before they develop full-fledged Alzheimer's. Improved cognitive tests are also showing promise as early diagnostic tools. Kawas and her colleagues showed that visual memory skill could predict Alzheimer's up to 15 years before diagnosis. People who have the most trouble drawing from memory simple shapes that they saw earlier run about twice the risk of developing Alzheimer's as those who perform better on the test, the researchers found. The results suggest that Alzheimer's begins long before symptoms arise, says Kawas. "It's beginning to look like Alzheimer's is a chronic process," says Kawas. "Some people in their 40s already have the [protein] deposits that may be the beginnings of Alzheimer's." Kawas says she hopes that researchers will find risk factors--such as diet--that can be manipulated in midlife to stave off the development of Alzheimer's later on. In the long run, early diagnosis helps only if it is coupled with effective treatment or prevention strategies. The drugs currently approved for Alzheimer's benefit about half of the patients who receive them--and only modestly. Still, getting these medications to people sooner could make a difference. "Research has shown that people gain 6 months and in a few cases as much as a year from taking current prescribed treatments," says Robinson. "Families are able to keep their loved ones at home a little longer using these therapies." This extra time at home benefits both the patient and the health care system, which isn't set up to minister efficiently to Alzheimer's patients, says Stephen McConnell, a public policy expert at the Alzheimer's Association. Experts agree that finding ways to prevent Alzheimer's disease--or at the very least, push back its onset--is crucial to averting a health care crisis, and predictive tests are the first step. If researchers can couple those tests with effective treatment and prevention strategies, they will ease countless minds. "When I cared for patients, they would tell me that they'd sooner be dead than lose their minds," says Evans. "It's the human cost of what's going to happen if we don't do something about this disease that is most worrisome." Christie Aschwanden is a freelance writer in Locarno, Switzerland, where she tests her verbal memory in three languages on a daily basis.