Today, arriving at a diagnosis of Alzheimer’s is often a prolonged and agonizing ordeal; Reagan’s doctors reportedly took a year to reach their verdict. The only certain diagnosis can be made by examining the brain after death, which reveals the nerve tangles and protein deposits, known as plaques, that characterize the disease. In living patients, doctors make a diagnosis-using verbal testing and a history from the family-only after eliminating other causes of mental deterioration, such as stroke, depression, overmedication or a tumor.
A team of researchers, led by Drs. Leonard Scinto and Huntington Potter of Harvard Medical School, knew that Down-syndrome patients who live past 30 develop brain lesions and dementia identical to those of older Alzheimer’s patients. (Chromosome 21 is involved in Down syndrome and some eases of Alzheimer’s.) They knew, too, that Down patients over 30 are hyperresponsive to the pupil-dilating drug tropieamide, the same drops your ophthalmologist uses to see inside your eyes. Seinto and his colleagues gave 19 patients with known or suspected Alzheimer’s eye drops containing an extremely diluted solution of tropieamide- about 100 times weaker than in ordinary use. The restills were dramatic. In 18 of the 19 Alzheimer’s patients, the pupils dilated 18 percent; in a control group of healthy elderly patients, the enlargement of the pupils was only 4 percent. The researchers don’t yet know whether the abnormal dilation can be found before Alzheimer’s symptoms occur.
Right now, with little help to offer Alzheimer’s patients (the only approved drug, taurine hydrochloride, is of limited usefulness and only in early stages of the disease), the prospect of a definitive test raises thorny ethical questions about who should have it performed. Suppose it turns out that the eye-drop test can identify those likely to get the disease years before they will be troubled by it? As long as the prognosis for Alzheimer’s remains so gloomy, early diagnosis could affect insurance, hiring or tenure and even marriage prospects.
Many researchers believe an accurate, simple Alzheimer’s test is an important first step in reaching a realistic goal: using yet-to-be developed drugs to delay the onset of symptoms for 5, 10 or even 20 years before any irreversible symptoms occur. Dr. Allen Roses and colleagues at Duke University Medical School have found that a normally occurring protein in the blood known as ApoE comes in several genetic variants. People who inherit two copies of the undesirable ApoE 4 are at risk for getting Alzheimer’s before 70, while those who inherit ApoE 2 and 3 tend not to get the disease until 10 to 20 years later. Within the next five years, Roses hopes to develop a drug that would mimic this apparently protective effect.
Scientists are also pursuing other treatments. At the University of Florida, researchers are studying how chemicals called cathecols could be used to help protect brain cells. The Alzheimer’s Disease Cooperative Study Unit, a national consortium led by Dr. Leon Thal of the University of California, San Diego, is recruiting Alzheimer’s patients to take part in trials of steroids; they may fight inflammation in the brain that could contribute to cell destruction. Postmenopausal estrogen may help prevent brain-cell death, and next summer several U.S. centers plan to begin a long-term study of some 100 women taking the hormone.
Already President Reagan’s disclosure has tripled the rate of calls pouring in to the national Alzheimer’s Association’s help line. And by stimulating more interest in the disease, leading to still more research, it could turn out to be the Great Communicator’s greatest communication of all.
