Mild Cognitive Impairment
Because the onset of AD is so slow and symptoms develop gradually over many years, there is a period during which people are slightly more forgetful than they used to be, and perhaps more forgetful than they ought to be. They don't yet have other cognitive or behavioral problems that would classify them as having AD, however. This is the condition that Dr. Petersen named mild cognitive impairment, or MCI. Classifying this condition has been a major boon to researchers because it has provided the parameters within which to study subtle changes in memory and other cognitive skills that may predict the development of AD.
Long-term studies at the Mayo Clinic's Alzheimer's Disease Research Center and with thousands of other research volunteers around the world suggest that people diagnosed with MCI will go on to develop dementia (usually Alzheimer's disease) at a rate of 10-15 percent a year. "We need to identify these people at this earlier stage so that therapies and interventions can be designed to prevent that progression," Dr. Petersen told us. "Ultimately we'd like to identify people who are at risk of developing Alzheimer's disease and other diseases when they still have no symptoms."
Since first describing the condition, Dr. Petersen and other researchers have developed a framework for understanding the causes and consequences of MCI by identifying subtypes. These subtypes are based on the most affected cognitive skills, which may reveal the areas of the brain that are affected as well. Amnestic MCI, the subtype in which memory problems are the most important feature, indicates possible involvement of the hippocampal formation, the memory center of the brain. Other types of MCI, called nonamnestic MCI, are characterized by declines in other cognitive skills, suggesting damage to other brain regions. For example, some people may have visual difficulties or trouble orienting themselves in space. They may be unable to reproduce a drawing or an arrangement of colored blocks. Such deficiencies suggest that other neurodegenerative diseases, such as frontotemporal dementia, as well as vascular or psychiatric conditions, might be causing this nonamnestic MCI.
The classification of two types of MCI—amnestic and nonamnestic—has been widely adopted by AD researchers and investigators conducting AD clinical trials. This framework may have a wider application as well. An understanding of amnestic MCI, combined with other diagnostic tools currently in development and drugs now undergoing clinical trial, may eventually help physicians diagnose and treat people before full-blown Alzheimer's disease has developed.
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Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.
In This Section
Momentum in Science: The Supplementary Series
- Understanding and Attacking Alzheimer's 12 min
- How Far We Have Come in Alzheimer's Research 15 min
- Identifying Mild Cognitive Impairment 20 min
- The Role of Genetics in Alzheimer's 12 min
- Advances in Brain Imaging 11 min
- Looking Into the Future of Alzheimer's 6 min
- The Connection Between Insulin and Alzheimer's 21 min
- Inflammation, the Immune System, and Alzheimer's 29 min
- The Benefit of Diet and Exercise in Alzheimer's 16 min
- Cognitive Reserve: What the Religious Orders Study is Revealing about Alzheimer's 20 min
- Searching for an Alzheimer's Cure: The Story of Flurizan 30 min
- The Pulse of Drug Development 15 min
- The DeMoe Family: Early-Onset Alzheimer's Genetics 25 min
- The Nanney/Felts Family: Late-Onset Alzheimer's Genetics 20 min
- The Quest for Biomarkers 17 min
Video: Inside the Brain: Unraveling the Mystery of Alzheimer's Disease
This 4-minute captioned video shows the progression of Alzheimer's disease in the brain.
Inside the Brain: An Interactive Tour
The Brain Tour explains how the brain works and how Alzheimer's affects it.
Alzheimer's Disease: Unraveling the Mystery
This book explains what AD is, describes the main areas in which researchers are working, and highlights new approaches for helping families and friends care for people with AD.
- About The Scientists
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- Rapid advances in our knowledge about AD have led to the development of promising new drugs and treatment strategies. However, before these new strategies can be used in clinical practice, they must be shown to work in people. Advances in prevention and treatment are only possible thanks to volunteers who participate in clinical trials.
- Among those touched by Alzheimer's (excluding self), nearly one-third provide support as a friend or relative, another 3% provide support as a healthcare professional, and the remaining two-thirds provide no support to the person suffering from Alzheimer's. When support is provided, it most often entails emotional support, followed by care-giving support. While small in comparison, more than one person in ten is providing financial support. Read more.