Ten years ago, Mayo Clinic investigators published a seminal paper on mild cognitive impairment (MCI). Since then, thousands of papers have appeared in the medical literature focusing on this early stage of cognitive disorders.
According to Mayo Clinic scientists, understanding MCI plays a critical role in the efforts to identify the earliest markers of Alzheimer's disease and develop therapies to stop or slow its progression. This month, Mayo Clinic investigators authored a review paper in the Archives of Neurology summarizing both the progress that has been made in the field of MCI and the challenges that remain.
Individuals with MCI can function reasonably well in everyday activities, but often have difficulty remembering details of conversations, events and upcoming appointments. Most (but not all) patients with MCI develop a progressive decline in their thinking abilities over time. Alzheimer's disease is usually the underlying cause.
"There is currently a push toward identifying individuals at the earliest clinical stage of Alzheimer's disease. This is important because the earlier you can intervene with therapies, the more likely you are to prevent further damage to the brain," says Ronald Petersen, M.D., Ph.D., neurologist and director of the Mayo Clinic Alzheimer's Disease Research Center. "Over the past decade, we've come to realize that MCI may represent the very earliest clinical features of Alzheimer's disease. Most studies, both here at Mayo Clinic and elsewhere, have demonstrated that individuals with MCI have an increased risk of developing Alzheimer's disease within two to five years."
The growing interest in MCI also has led to a variety of drug treatment trials that have tested whether it's possible to slow the progression of MCI to Alzheimer's disease. According to Dr. Petersen, almost all of these trials have been negative, but it continues to remain an active area of investigation.
"We're optimistic with regards to potential treatment for MCI and, ultimately, Alzheimer's disease," says Dr. Petersen. "MCI is a stage at which individuals are minimally symptomatic, but there is a great deal left to preserve. As researchers and pharmaceutical companies work to design therapies to intervene at the earliest possible stage, we're hopeful that we'll eventually be able to stop or slow the rate of cognitive decline."
The Mayo Clinic Study of Aging has played a significant role in the past decade's MCI research. This population-based study in Olmsted County, Minn., involves nearly 3,000 participants aged 70 through 89 years who were cognitively normal or had MCI at the onset of the study. Using this population, Mayo Clinic researchers estimate the prevalence of MCI at approximately 15 percent. Another way Mayo Clinic investigators are participating in the current research efforts is through leadership in the Alzheimer's Disease Neuroimaging Initiative (ADNI), a major investigation sponsored by the National Institute on Aging and a consortium of pharmaceutical imaging companies and not-for-profit organizations. ADNI is designed to evaluate the role of imaging measures and chemical biomarkers in predicting who will develop Alzheimer's disease. The major clinical focal point of the study is on patients with MCI and assessing the value of imaging and chemical biomarkers at the earliest possible stage in disease progression.
"We believe MCI serves an important role in advancing our understanding of disease mechanisms with the ultimate goal of finding preventive therapies," says Dr. Petersen. "The progress over the past 10 years is significant, and I'm hopeful our progress will be even greater in the next decade."
Other Mayo Clinic scientists involved in this research include Rosebud Roberts, M.B., Ch.B.; David Knopman, M.D.; Bradley Boeve, M.D.; Yonas Geda, M.D.; Robert Ivnik, Ph.D.; Glenn Smith, Ph.D.; and Clifford Jack, M.D.
About Mayo Clinic
Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. Doctors from every medical specialty work together to care for patients, joined by common systems and a philosophy of "the needs of the patient come first." More than 3,700 physicians, scientists and researchers, and 50,100 allied health staff work at Mayo Clinic, which has campuses in Rochester, Minn; Jacksonville, Fla; and Scottsdale/Phoenix, Ariz.; and community-based providers in more than 70 locations in southern Minnesota., western Wisconsin and northeast Iowa. These locations treat more than half a million people each year.
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