All is lost, insist researchers.

• Position: Alzheimer's Disease - Disease/Disorder overview

Alzheimer's disease has joined cancer at the top of the list of feared diagnoses and, although it does have the potential to devastate millions of patients and families, there are reasons for hope--and possibly opportunities to reduce risk or alter the course of the disease's progression. maintains Keith Black, professor and chair of the Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles, Calif.

"With no cure, no effective treatment, and not even a reliable, practical way to diagnose it, Alzheimer's has become one of the most dreaded diseases of our time," notes Black. "When we talk about new noninvasive technology aimed at providing early detection, many people say they wouldn't want to know in advance. The outlook is just too frightening and they say there's nothing they could do about it anyway--but there's a lot of misinformation about the disease, and emerging data suggests that some very simple things we can do right now might change its course, especially if we intervene early in disease progression--years before symptoms begin."

Until recently, the hallmark changes in the brain leading to a diagnosis of Alzheimer's disease could be seen only after death, in brain sections treated to reveal plaques containing beta-amyloid protein and neurofibrillary tangles containing abnormal tau protein. Special imaging studies--positron emission tomography, or PET scans and tests of cerebrospinal fluid now offer the best, though imperfect, chance to detect and diagnose the disease in living patients. However, spinal taps cause discomfort and PET scans require injection of a radioactive tracer. Yet, even if the tests were 100% accurate, they would not be convenient, practical, or cost-effective as an early screening method, Black emphasizes.

"A few years ago, we discovered that beta-amyloid plaques occur not only in the brain, but in the retina in the back of the eye, which is literally an extension of brain tissue. We also found that the plaques can be seen in the retina even before they begin to accumulate in the brain, and we developed a device that enables us to look through the eye--just as an ophthalmologist looks through the eye to diagnose retinal disease--and see these changes.

"Preliminary results suggest the optical imaging device may be extremely predictive, possibly providing earlier detection...