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Is It Mild Cognitive Impairment or Alzheimer's Disease?

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Updated March 07, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

What Is Mild Cognitive Impairment (MCI)?

Mild cognitive impairment is a decline in cognition, including concentration, communication, memory and orientation. These declines may also impact the person’s ability to conduct daily activities in such areas as dressing, bathing and eating meals.

MCI is often thought of as the period between normal cognition and when Alzheimer’s disease develops. Others consider it to be the actual early stages of Alzheimer's, although not everyone with MCI will develop Alzheimer’s. Some people may be given a diagnosis of MCI, experience a reversible dementia and then return to normal cognitive functioning.

Changing Definitions of MCI

The definition of MCI has continually evolved. In the initial guidelines for a diagnosis of MCI, the only area an individual could demonstrate impairment in was his memory. All other cognitive functioning had to remain intact.

The definition was then revised, and it allowed for problems in other cognitive areas, such as reasoning and judgment. However, the person had to continue functioning quite well in daily life; if activities of daily living were impacted, the diagnosis would then likely be dementia, or specifically, the early stages of Alzheimer's disease.

More recently, researchers found that this definition was not fitting with what they found in their evaluations of those who were diagnosed with MCI, since many people with MCI in their study did indeed demonstrate a functional impairment.

Because of this, a team from the Alzheimer's Association and National Institutes of Aging recommended another revised definition of MCI in 2012. This one allowed for mild impairment in activities of daily living, in addition to the cognitive challenges outlined above. While it gives more flexibility and perhaps is more accurate, it also may result in some people who were already diagnosed as having Alzheimer’s or another dementia now fitting the criteria for MCI instead.

In effect, the newly revised definition blurs the line between MCI and Alzheimer’s, so some researchers recommended that the term MCI due to AD (Alzheimer’s disease) be used, unless it's clear that the MCI is related to other potentially reversible causes, such as normal pressure hydrocephalus or vitamin B12 deficiency.

Prevalence of MCI

It’s estimated that about 20% of people over the age of 70 have MCI. After receiving a diagnosis of MCI, the majority will develop Alzheimer’s within five years. Generally, as people age, they are more likely to develop MCI, as well as Alzheimer’s disease.

What Causes MCI?

The cause of MCI is unknown. It does appear to have similar risk factors to Alzheimer’s, such as age, education and such brain/body health factors as stroke, diabetes, cholesterol, heart health and blood pressure.

What’s the Difference Between MCI and Alzheimer’s Disease?

Many, but not all, cases of MCI develop into Alzheimer’s disease. Symptoms of Alzheimer’s disease do begin with MCI. MCI is a general term for mild impairments in thought processes and memory, whereas Alzheimer’s is a specific disease in which memory and functioning continue to decline over time.

There is some support for considering MCI simply to be a very early stage of Alzheimer’s. Studies have shown changes in the brains of people with MCI similar to the changes that are present in Alzheimer’s.

What’s the Difference Between MCI and Normal Age-Related Memory Changes?

As people age, it’s normal for them to experience some occasional memory gaps, such as not being able to remember someone’s name that they haven’t seen for awhile or where they set down their favorite pen. A periodic delay in being able to access memories is also typical as we age. What’s not normal, and moves people toward an MCI diagnosis, is the experience of additional concerns in the areas of language, judgment and problem-solving, or when the memory loss is more than just occasional.

Individuals with normal age-related memory changes have less of a chance of developing Alzheimer’s disease than those already diagnosed with MCI.

Treatment of MCI

There is no medication approved for treatment of MCI at this time. Some physicians do opt to prescribe donepezil (Aricept), since it has been researched as a treatment for MCI and has shown some benefit. Other physicians recommend general risk-reduction strategies similar to what is recommended for Alzheimer’s, including maintaining healthy eating habits, an active brain and regular social interaction.

Sources:

Alzheimer’s Memory Center. Mild Cognitive Impairment. Accessed February 24, 2012. http://www.amcneurology.com/blog/2009/12/02/mild-cognitive-impairment-mci/

Journal of Alzheimer’s Disease. Effects of Varying Diagnostic Criteria on Prevalence of Mild Cognitive Impairment in a Community Based Sample. Accessed February 24, 2012. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146555/

Morris, J. Archives of Neurology. February 6, 2012. Revised Criteria for Mild Cognitive Impairment May Compromise the Diagnosis of Alzheimer Disease Dementia. Accessed February 7, 2012. http://archneur.ama-assn.org/cgi/content/full/archneurol.2011.3152

Neurology. Longitudinal pattern of regional brain volume change differentiates normal aging from MCI. Accessed February 24, 2012. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690968/

NYU Langone Medical Center. Mild Cognitive Impairment. Accessed February 23, 2012. http://www.med.nyu.edu/adc/forpatients/cognitiveimpair.html#what

University of California, San Francisco. Mild Cognitive Impairment. Accessed February 7, 2012. http://memory.ucsf.edu/education/diseases/mci

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