lzheimer’s disease is by far the most common cause of dementia and one of the world’s most feared disorders. By 2050, there will be 135 million Alzheimer’s sufferers worldwide, a threefold increase from today, with three-quarters of cases occurring in low- and middle-income countries. Predicting the onset of Alzheimer’s, let alone preventing or curing it, remains an immense challenge.
Alzheimer’s disease was identified more than a century ago from autopsy results that showed characteristic brain lesions called “amyloid plaques.” The disease is more difficult to diagnose in the living. Doctors rely on observation of memory loss and other thinking deficits (such as reasoning or language comprehension) ”“ signs that plaques are already present in the brain. But any cure would have to be administered before the plaques form, and years before symptoms of dementia appear.
Alzheimer’s might be more predictable if scientists had the time and resources to conduct far-reaching longitudinal studies over many years. Such studies ideally would involve blood, imaging, memory, and medical tests, as well as detailed lifestyle questionnaires filled out by thousands of young and middle-aged people. Study participants would be followed over decades to see who developed the disease, and which tests proved positive before Alzheimer’s was diagnosed.