Mild Cognitive Impairment vs. Alzheimer's

Memory Loss Can Be a Symptom of Mild Cognitive Impairment
Peter Dazeley Photographer's Choice 585506011/ Getty Images

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 activities of daily living 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.

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, the revised definition also blurs the line between MCI and Alzheimer’s.

Consequently, some researchers have recommended that the term MCI due to AD (Alzheimer’s disease) be used, unless it's clear that the symptoms of MCI are 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. Generally, as people age, they are more likely to develop MCI, as well as Alzheimer’s disease.

More about Progression of MCI to Dementia

People with MCI are at a higher risk of progressing to Alzheimer's disease; however, despite this risk, not everyone does. One study found that after a diagnosis of MCI, 40% of people "reverted" (that is, their cognitive abilities returned to normal) for a time, although they were significantly more likely to develop Alzheimer's within 5 years when compared with those who never had MCI.

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?

Symptoms of Alzheimer’s disease typically begin with MCI. MCI refers to relatively minor impairments in thought processes and memory, whereas Alzheimer’s is a specific disease in which memory and functioning continue to significantly decline over time.

Some researchers would like to identify MCI simply as a very early stage of Alzheimer’s, especially because studies have shown changes in the brains of people with MCI that are similar to those that are present in Alzheimer’s. However, since some people who are diagnosed with MCI don't continue to decline or show other symptoms of dementia, this definition is unlikely. 

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.


Alzheimer’s Memory Center. Mild Cognitive Impairment. Accessed February 24, 2012.

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.

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.

Neurology. Longitudinal pattern of regional brain volume change differentiates normal aging from MCI. Accessed February 24, 2012.

Neurology. Mild cognitive impairment and progression to dementia: New Findings. 2014.

NYU Langone Medical Center. Mild Cognitive Impairment. Accessed February 23, 2012.

University of California, San Francisco. Mild Cognitive Impairment. Accessed February 7, 2012.

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