Mild Cognitive Impairment vs. Alzheimer's Disease

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

Overview

It’s estimated that about 20 percent 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.

MCI is often thought of as the period between normal cognition and when Alzheimer’s disease develops. Others consider it to be an actual early stage of Alzheimer's, although not everyone with MCI will develop Alzheimer’s.

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 memory. All other cognitive functioning had to remain intact.

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

A group of researchers found that this definition was not always 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 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.

Causes

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

Progression 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 percent 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 five years when compared with those who never had MCI.

How MCI Differs From Alzheimer’s

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. 

MCI vs. Normal 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

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, physical activity, an active brain, and regular social interaction.

A Word From Verywell

While it's normal to feel worried if you see some of the symptoms of MCI in yourself, it's important to see your doctor for an evaluation since some cognitive problems are at least partially reversible with appropriate treatment. It's also possible that your doctor's appointment could provide some reassurance that you're simply experiencing some normal, age-related memory loss

It's important to remember that, while some people with MCI eventually develop Alzheimer's, others do not. Some people with MCI even function reasonably well and remain stable for many years.

Sources:

Alzheimer's & Dementia. (2011) 1–10. The diagnosis of mild cognitive impairment due to Alzheimer’s disease: Recommendations from the National Institute on Aging and Alzheimer’s Association workgroup

Journal of Alzheimer’s Disease. Effects of Varying Diagnostic Criteria on Prevalence of Mild Cognitive Impairment in a Community Based Sample.

Morris, J. Archives of Neurology. February 6, 2012. Revised Criteria for Mild Cognitive Impairment May Compromise the Diagnosis of Alzheimer Disease Dementia.

Neurology. Longitudinal pattern of regional brain volume change differentiates normal aging from MCI

Neurology. Mild cognitive impairment and progression to dementia: New Findings. 2014. http://www.neurology.org/content/82/4/e34.full.pdf

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