This is an exciting time to be involved in Alzheimer’s disease research, as a great deal has been discovered about its underlying biology as the disease progresses. Clinicians and scientists are now able to detect some of the earliest features of developing Alzheimer’s — even prior to the onset of symptoms such as forgetfulness. It is hoped that this will lead to intervention with treatments that will be effective very early in the disease process.
Much of the information regarding the early presentation of Alzheimer’s disease has occurred through the discovery of biomarkers. Biomarkers are biological signals in the brain that allow clinicians to detect the Alzheimer’s process beginning very early in the disease process. For example, amyloid, the protein thought to be a key player in the development of the disease, forms the basis of one of Alzheimer’s hallmarks — neuritic plaque. Clinicians are now able to detect the presence of amyloid in the brain of normal living individuals who are asymptomatic. That is, either by using positron emission tomography (PET) scans or through lumbar punctures and analyzing the cerebrospinal fluid, clinicians are able to detect the presence of the amyloid protein in the brain. These findings have led to several clinical trials aimed at either preventing the buildup or enhancing the removal of the amyloid protein from the brain. Currently, this is a very active area of research.
The other biological hallmark of Alzheimer’s disease is the development of the neurofibrillary tangle in the brain. Alzheimer’s disease has been characterized as a “plaque and tangle disease,” and identification of these two entities in the brain has led to the potential for early treatment. The neurofibrillary tangle is comprised of the protein, tau, and we are developing techniques to detect tau in the brain in much the same way as we have done with amyloid. PET scanning has been developed to enable us to see the tau protein buildup in the brain of normal individuals. In addition, with a lumbar puncture, we can see evidence of the tau protein in the cerebrospinal fluid, as well. These findings give us the opportunity to view the two major determinants of the disease process early in its course. Therapies for the treatment of the tau protein lag behind those for amyloid but are very much on the radar screen of scientists.
We are hopeful that we will be able to, in the not too distant future, identify people who are at risk of developing Alzheimer’s disease, possibly by obtaining these biomarkers on individuals when they are normal, and then intervening with effective therapies. By attacking the disease as early as possible, we will potentially be able to delay the onset of clinical symptoms or possibly even prevent them if we are successful. This approach will have a significant impact on the numbers of individuals who will develop the disease in the future; and with the aging of America, this is becoming a public health priority. While much work remains to be done, we continue to see significant progress toward developing effective therapies for Alzheimer’s disease.
Dr. Petersen is considered an international expert in Alzheimer’s disease, early-onset dementia and related neurodegenerative diseases. In addition to directing the Mayo Clinic Alzheimer’s Disease Research Center and the Mayo Clinic’s Robert and Arlene Kogod Center on Aging, Dr. Petersen also chairs the Advisory Council on Alzheimer’s Research, Care and Services.