Can Alzheimer's disease be predicted? And if it could, would you want to take the test?

Those questions are being sparked by three new studies, each of which presents a potential method for foretelling, years in advance, the memory loss and cognitive impairment that are the hallmarks of the debilitating brain disease.

Researchers have already identified genetic risk factors that give some people higher odds of one day contracting Alzheimer's. The new studies are different: They propose that certain "biomarkers" of the disease may be detectable after it has begun to affect the brain, but before symptoms have become apparent.

The three studies target different biomarkers in different places: one in the blood, one in the cerebrospinal fluid, and one in the brain