Early diagnosis and intervention in Alzheimer’s disease is an important target for researchers and clinicians, since it may lead to better outcomes, new interventions, as well as more time to learn about the disease and prepare for significant life changes. This has led to new research studies attempting earlier detection of cognitive decline in late life. The early changes are termed "mild cognitive impairment," or MCI. This concept has caught the interest of the dementia research community and also has the interest of practicing neurologists, primary care physicians, and psychiatrists who see such patients.

With an emphasis on early intervention so that medications may have greater impact, identifying people very early with cognitive decline or people who are at risk becomes increasingly important. The early diagnostic assessments were not focused on sensitivity to detect the earliest manifestations. New studies looking at people who had been followed in longitudinal population studies and developed dementia, or studies of people who became mildly memory impaired and who evolved over time into full-blown dementia, have been the basis for our new understanding. Data suggests that people who develop a relatively isolated memory disorder can evolve into full-blown Alzheimer’s disease at the rate of 10 to 15% per year, quite above the equal age-associated rate of 1 to 2% per year. Obviously we would want to identify these people. A particularly active area of research focuses on the earliest changes that can be identified on cognitive assessment or on scans such as MRI or PET.

Our paper on MCI was important because it was part of an evidence-based search of the literature to provide the best practices for diagnosis (Knopman, et al., same issue) and treatment (Doody, et al., same issue) of dementia, organized by the Practice Parameters Subcommittee of the American Academy of Neurology (AAN). Papers to be included in the analysis had to meet certain standards of evidence. This particular document, on MCI, was intended to inform physicians of an advancing field that would probably have a significant impact on the way they practice, and to some extent to set an agenda for how we do research on early cases.

In layman’s terms, this paper outlines the issues and the data supporting our ability to identify, much earlier than previously, the memory and thinking changes that will eventually develop into Alzheimer’s disease. With current and [hopefully] more-powerful future therapies, identifying these people sooner will likely make their treatments more effective. For the present, the ability to alert physicians to the patterns of cognitive impairment that don’t meet the criteria for dementia but do represent its early signs will enable them to monitor such patients closely and intervene as soon as it is deemed appropriate.

My involvement in this research stems from my clinical and basic research in Alzheimer’s disease over the past 25 years. This particular project was the result of a great deal of work by a very diligent group of investigators in Alzheimer’s disease, comprising neurologists, geriatric psychiatrists, geriatricians, and other researchers (please see the list of authors for this paper). I co-chaired, with Dr. Jeffrey Cummings, the Dementia Practice Parameters Committee that did the literature search and the individual evaluations of all papers that evaluated mild cognitive impairment and its outcomes. Many of the members of this committee, including myself, had been involved in the evaluation of patients with MCI who had presented to a clinic, as well as in following patients in epidemiological long-term studies and observing the decline in memory function and other cognitive domains that eventually led to manifest Alzheimer’s disease. In the course of trying to identify both the earliest clinical and biological changes that occur in people who are going to develop Alzheimer’s disease, I and many colleagues have been increasingly led to study MCI and people who are at risk for developing dementia, in an effort to facilitate efforts to blunt the effect of the coming epidemic in Alzheimer’s disease and other late-life dementias.