The onset of Alzheimer's is not a sudden thing, which reinforces the view of it as a lifestyle disease: "The first changes in the brain of a person with Alzheimer's disease can be observed as much as ten years in advance - ten years before the person in question has become so ill that he or she can be diagnosed with the disease. [Researchers] are studying biomarkers - substances present in spinal fluid and linked to Alzheimer's disease. The group has studied close to 140 people with mild memory impairment, showing that a certain combination of markers (low levels of the substance beta-amyloid and high levels of the substance tau) indicate a high risk of developing Alzheimer's disease in the future. As many as 91 per cent of the patients with mild memory impairment who had these risk markers went on to develop Alzheimer's within a ten-year period. In contrast, those who had memory impairment but normal values for the markers did not run a higher risk of getting Alzheimer's than healthy individuals. ... This is a very important finding with regard to the development of new therapies against the disease. All prospective therapies have so far shown to be ineffective in stopping the disease, and many people are concerned that the pharmaceutical companies will give up their efforts in this field. But these failures may depend on the fact that the new therapies were initiated too late. When a patient receives a diagnosis today, the damage has already gone too far." I'm not sold on this last comment, given the evidence suggesting that Alzheimer's symptoms are reversible.