What is Mild Cognitive Impairment?

Memory loss has long been viewed as an inevitable product of aging. More recently, physicians and researchers have adapted their view and now believe that a certain degree of memory loss can represent an underlying disease process occurring in the brain.

The term “dementia” has been used to characterize memory loss that exceeds what is expected during the normal aging process. People with dementia are unable to function independently at their typical level. They may no longer be able to manage their personal finances or provide for their own basic needs. It’s important to know that dementia has many causes; Alzheimer’s disease is the most common.

Many older individuals may complain of memory problems, but still manage to independently perform all of their day‐to‐day tasks. Because their memory problems do not interfere with daily activities, these people do not meet criteria for a diagnosis of dementia. This cluster of symptoms, in which a person experiences significant problems with memory, language or other functions severe enough to be noticeable to other people and show up on tests of memory, but not serious enough interfere with daily life, has been called Mild Cognitive Impairment (MCI).

Researchers now believe that MCI often represents cognitive decline that reflects a degenerative brain process beyond the scope of normal aging but precedes more severe deterioration and a diagnosis of dementia. MCI is a condition in which a person has problems with memory or thinking that are greater than those anticipated for his or her age. However, people with MCI do not have the more severe cognitive problems or functional changes that characterize Alzheimer’s disease. MCI has several types. The type most associated with memory loss is called amnestic MCI.

Until recently, physicians were not able to provide any specific information concerning the significance of MCI. However, in the last few years, there has been a substantial increase in the number of studies focusing on patients with complaints of early memory loss. Although much more work still needs to be done, doctors and researchers have made significant progress in characterizing these early memory problems and their potential outcomes.

The early stages of dementia appear as subtle changes that may only be noticeable to a trained professional or a close family member or friend. People in the early stages of MCI will often compensate for their memory problems with strategies like making lists, keeping notes, and relying more often on a calendar.

Several studies have shown that memory complaints in the elderly are associated with a higher‐than‐average risk of developing dementia in the future. Approximately 60% of people who meet formal criteria for MCI (i.e., memory complaint plus evidence of memory impairment on memory tests) develop Alzheimer’s disease within five years. However, it is also clear that some patients with MCI will never develop dementia.

Several studies have suggested that results of certain imaging procedures like MRIs and PET scans can help to determine an individual’s risk for developing dementia in the future. Researchers are now focusing their efforts on characterizing the stage of the Alzheimer’s disease spectrum that precedes MCI.

Researchers at Brigham and Women's Hospital and Massachusetts General Hospital are actively seeking participants showing symptoms of MCI to participate in several studies to help them better understand the causes of MCI. There are also studies for older individuals with even milder memory changes that use brain scans to try to predict who may develop more severe problems and progress towards Alzheimer’s dementia. There are also ongoing clinical trials of medications aimed at decreasing Alzheimer’s pathology in the brain. With better knowledge of the earliest stages of MCI, researchers may be able to test potential treatments at earlier stages, when they may have the greatest promise for slowing down progression of this devastating disease. To learn more these studies, please see the study pages listed below.

Observational Studies

Alzheimer's Disease Neuroimaging Initiative - 2 (ADNI-2): A study to determine whether imaging of the brain can help predict onset and monitor the progression of cognitive change.

Evolution of memory-related fMRI activation over the course of MCI and AD: Identifying Early Biomarkers of Alzheimer's Disease