YOU ASKED, WE ANSWERED: Expert Responses to Alzheimer's Queries

We read through hundreds of your questions and submitted some for Dr. Ronald Petersen, director of the Mayo Alzheimer's Disease Research Center and professor of neurology at the Mayo Clinic College of Medicine, to answer. His answers to viewers' most common questions are below.

Bruce from New Haven, Conn., asked: "The ABC story reports that 30+ minutes of exercrise several times/wk lessens the risk ofAlzheimer's. Aerobic exercise? What intensity of exercise? How measured -- by heart rate?"

Dr. Petersen answered: The data regarding these issues are somewhat lean. The published reports indicate that, if a person exercises at least three times per week, presumably for 30 to 45 minutes to a sufficient heart rate to perspire during that time frame, this might be beneficial. But I must emphasize, the precise prescription for how much exercise and for how often is uncertain.

Ann from Olean, N.Y., asked: "Does it matter at what age you start exercising?"

Dr. Petersen answered: In general, the earlier the better. However, a recent study from the University of Washington indicated that, even when older individuals begin exercising late in life, it can be beneficial to them. Consequently, we certainly would recommend that people exercise on a regular basis at any age, the sooner the better.

David from Knoxville, Tenn., asked: "What foods might be helpful in delaying the onset of Alzheimer's or mild cognitive impairment?"

Dr. Petersen answered: There is some evidence in the literature that a Mediterranean diet may be beneficial for the prevention of dementia and Alzheimer's disease. In general, we usually recommend that people follow a "heart healthy" diet that is likely to benefit not only cardiovascular function but perhaps cognitive function, as well.

James from Rochester, N.Y., asked: "In the story this evening that focused on physical activity not only preventing Alzheimer's but also allowing existing plaque to be removed, my question is, does this provide an opportunity for future research to eradicate this frustrating disease? My mother is in the early stages of the disease and it's just tragic to know she'll never get better. Thank you."

Dr. Petersen answered: We certainly hope that there will be a cure for Alzheimer's disease, but in the short run, we are attempting to delay the onset of the disease and perhaps slow the progression. If we are successful at either of these goals, it is likely that we will have a significant impact on the number of persons developing Alzheimer's disease. Alzheimer's is a complex disease, and there may not be a simple single cure for all of its subtypes, but we are attempting to reduce its impact by delaying the onset.

"CF" from Riverside, Calif., asked: "My mother is 83 and is now demonstrating obvious signs of Alzheimer's, but she is very healthy and walks and could do more exercise ... can exercise help to stabilize the disease."

Dr. Petersen answered: A recent study did indicate that when older individuals exercise, there may be improved cognitive function, as well. Definitive studies in Alzheimer's disease are less clear, and while we still recommend that individuals stay intellectually and physically active even into the disease, a precise documentation of the benefit of these recommendations is lacking.

Vicki from San Jose, Calif., asked: "My mother was diagnosed with severe dementia at age 89. How does that differ from Alzheimer's? Is dementia a precurser to Alzheimer's? Do both Alzheimer's and dementia tend to be hereditary? Would exercise ward off dementia as well as Alzheimer's? Thank you."

Dr. Petersen answered: Dementia is the umbrella term we use to describe an impairment in memory and at least one other cognitive function, such as language, attention or problem solving. The cognitive impairment must be of sufficient severity to compromise daily activities, and if so, that constitutes dementia. Among the dementias, there are multiple causes, and Alzheimer's disease is the most frequent cause, especially in elderly individuals. Therefore, Alzheimer's disease is one type of dementia due to a degenerative disease of the brain and involves certain pathologic features that are characteristic of the disorder.

Addella from Leisuretown, N.J., asked: "I have been diagnosed with mild to moderate 'Visual Alzheimer's.' What can I do to slow the progression?"

Dr. Petersen answered: "Visual Alzheimer's" is a particular variant of general Alzheimer's disease. In people with visual Alzheimer's, the posterior parts of the brain are more affected than the memory parts. Consequently, these individuals will have difficulty with visuospatial functions. Nevertheless, if the underlying cause of the visual problems is due to Alzheimer's pathology, all of the information that is available that pertains to Alzheimer's disease would be applicable to the visual variant of Alzheimer's disease, as well.

Louise from Bethesda, Md., asked: "Is Alzheimer's disease found primarily in those with a genetic link to others with the disease?"

Dr. Petersen answered: Generally speaking, there are two forms of Alzheimer's disease: familial Alzheimer's disease and sporadic Alzheimer's disease. Familial Alzheimer's disease is actually quite rare, but in these unusual circumstances, there is a definite inherited pattern for the disease. Typically, this occurs earlier in life with individuals in their 30s, 40s or 50s being affected. The vast majority of Alzheimer's disease is so-called sporadic or late onset Alzheimer's disease. There may be a genetic component to it, but it is not inherited in a definitive pattern.