What is Mild Cognitive Impairment?

Memory, forgetfulness and aging. What is mild cognitive impairment and how is it different from normal aging or dementia? Can it be reversed and the 30 question cognitive test. Matt Huentelman, Ph.D., explains.

Mild cognitive impairment (MCI) is characterized by changes in cognitive performance that are uncommon or atypical for someone’s age and education level.

Many older adults wonder if their forgetfulness or confusion episodes are part of normal aging. But their everyday life functions are not impacted at all. And what they usually experience are very subtle changes in memory, thinking, ability to express through language, in sense of direction or navigation, or remembering instructions, planning and other executive functioning skills.

MCI is often thought of as a stage between “normal aging” and dementia. Since it’s not dementia, the implication is that mild cognitive impairment is typically not significant enough to impact your daily life.

What are the Symptoms of Mild Cognitive Impairment?

In most cases the person with MCI may have no noticeable symptoms.

Sometimes, the person has some memory loss complaints or is worried about dementia. Or one of their friends or family members has concerns about their cognitive abilities.

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What people tend to notice are cognitive decline or memory and thinking changes similar to those found in Alzheimer's disease. These would be some of the cognitive warning signs or symptoms of mild cognitive impairment.
Symptoms of mild cognitive impairment.

What people tend to notice are cognitive decline or memory and thinking changes similar to those found in Alzheimer’s disease.

  • Feeling overwhelmed by decision making or planning activities.
  • Missing appointments or important events.
  • Forgetting words or feeling like the words are on the tip of your tongue. That’s called aphasia.
  • Losing your sense of direction. Having a hard time navigating around the city that you know very well. Not a new city.
  • Having difficulty understanding complex instructions.

Those would be some of the cognitive warning signs.

All of us have these instances where we forget someone’s name, a word, or why we walked into the kitchen, but those are much fewer and far between than we will admit to ourselves. We are usually extra hard on ourselves when it comes to our own forgetfulness.

When it happens, we get nervous about it. But it doesn’t affect our daily life.

We may forget why we went to the kitchen, but eventually we remember what we were doing, what we forgot. This is quite different from not being able to find our way back home after going to the grocery store. That’s a problem, that affects our daily life. Forgetting where we left our keys for a few hours, that’s normal.

How is MCI Diagnosed?

Mild cognitive impairment is primarily identified in people who already have concerns about their cognition but, when tested, they don’t quite rise to the clinical definition of dementia. Their memory or thinking abilities have declined over time but this does not impact their day-to-day activities.

This cognitive impairment is assessed through the use of standardized memory and thinking tests administered by a health care professional.

When doctors assess a person’s mental performance, an MCI patient’s score may show a mild level of impairment for their age and education level. Medical professionals use tests such as the Mini-Mental State Examination (MMSE) or the Montreal Cognitive Assessment (MoCA) to do these evaluations.

The results for a person with MCI are typically not significant enough to be labeled dementia. It is important to note that a diagnosis of MCI typically requires significant clinical judgment by your doctor and this could include multiple tests of your memory and cognition, images of your brain, and blood tests.☜

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What is the Difference between MCI and Dementia?

Both MCI and dementia are characterized by objective evidence of cognitive impairments. The main difference between mild cognitive impairment and dementia is that in the latter there is evident interference with daily life functioning.

Another big difference between MCI and dementia is simply that based on your testing, you fall into the range of the memory scores that we would consider not to be dementia.

Is there Physical Evidence of Mild Cognitive Impairment in the Brain Tissue?

When you look at the brain of someone who died with a determination of MCI, often times you can see some of the same changes that we see with other degenerative brain diseases that can lead to dementia.

Those include changes that we see with Alzheimer’s disease (AD), Parkinson’s disease, and vascular dementia.

In summary, if you look at the brain of a collection of people with MCI, you would see a whole array of changes that we see in the brain in normal aging as well as in dementia.

These changes may include:

  • abnormal clumps of amyloid proteins (plaques) and tau tangles, characteristic of Alzheimer’s disease
  • microscopic deposits of a protein called alpha-synuclein that can form Lewy bodies, associated with Parkinson’s disease and Lewy Body dementia
  • small strokes or reduced blood flow in brain blood vessels due to blockages and/or vascular damage
  • shrinkage of the hippocampus
  • brain ventricle enlargement

And their levels would often range between those seen in normal aging and those found in patients with dementia. It is important to note that these are generalities and each patient may be different.

Abnormal Clumps of Proteins

If you looked at three groups of people, normal aging, mild cognitive impairment and, let’s say, Alzheimer’s disease patients. And we looked at hundreds of people’s brains in each of those groups, the average level of amyloid plaques would be low in normal aging, high in the Alzheimer’s disease group and somewhere in the middle for MCI.

Small Strokes or Cerebrovascular Disease

Some strokes can be seen with brain imaging. Significant strokes are generally caught when a person is alive because they will have symptoms associated with them.

But you can observe so-called mini strokes under the microscope when you look at the brain following death. You may observe evidence that blood has leaked out from the blood vessels and into the brain tissue.

As with the abnormal clumps of proteins, the MCI group would fall in between a group of dementia patients and normal aging individuals with regards to these blood vessel changes.

The same group differences would apply to shrinkage of the hippocampus.

Ventricle Enlargement

The ventricles circulate your cerebrospinal fluid, or CSF, which bathes your brain. CSF is important to manage the balance of nutrients in the brain and to aid in the removal of toxins. 

Humans have four brain ventricles. They are spaces or cavities filled with cerebrospinal fluid.

Physical Evidence of Mild Cognitive Impairment in the Brain Tissue: Ventricle Enlargement.
Physical Evidence of Mild Cognitive Impairment in the Brain Tissue: Ventricle Enlargement.

When large numbers of cells die – this results in an overall shrinkage of the brain tissue. Since the brain and spinal cord are a closed system, our ventricles enlarge to compensate for this loss of brain tissue. This enlargement can be observed in the brain of patients with advanced Alzheimer’s disease.

It sounds like we’re  discussing two findings. Cells are dying and ventricles are getting bigger, but really they’re linked to each other. And more often than not, both of them are very obvious. For example, if we weigh the brain at death, it weighs less in a patient with Alzheimer’s disease.

What is Mild Cognitive Impairment with Memory Loss (Amnestic MCI)?

Amnestic MCI is the form of mild cognitive impairment that looks more like early Alzheimer’s disease because it is accompanied by memory loss as the primary symptom.

People with an amnestic MCI diagnosis  have a higher probability of progressing to Alzheimer’s disease than non-amnestic MCI individuals.

What are the other Types of MCI?

MCI is split into two groups: amnestic and non-amnestic.

In non-amnestic MCI, cognitive abilities  like language, executive functioning, and visual-spatial skills are impaired.

Typically, in the non-amnestic MCI patient, memory problems are not the primary concern.

At what Age does Mild Cognitive Impairment Start?

This is different for each person. The American Academy of Neurology estimates that 15% of individuals over the age of 65 may meet certain criteria for a diagnosis of MCI.

Memory, forgetfulness and aging. What is mild cognitive impairment and how is it different from normal aging or dementia? Can it be reversed and the 30 question cognitive test. Matt Huentelman, Ph.D., explains.
Memory, forgetfulness and aging. What is mild cognitive impairment and how is it different from normal aging or dementia? Can it be reversed and the 30 question cognitive test. Matt Huentelman, Ph.D., explains.

How Fast does Mild Cognitive Impairment Progress?

This is also different for each person, and we don’t have good ways of telling how fast MCI is going to progress.

But usually this question is about how long do I have before I get an Alzheimer’s diagnosis or how long before I recover. Because people with mild cognitive impairment can recover.

Progression to dementia typically takes many years. Research suggests that this number is between 3-5 years for the majority of amnestic MCI patients – but it can be shorter and it can be longer than this.

If the MCI is caused by medication use, recovery back to normal can be rapid, occurring during the course of a few months or so. However this can depend on how long one was taking the medication and how long it remains in the body after stopping the last dose.

Can MCI be Reversed or Does it Always Lead to Dementia?

MCI can follow three patterns: functions can get progressively worse, remain stable, or revert back to normal. So, the answer to the question is yes, it can be reversed and it does not always lead to dementia.

MCI can sometimes be caused by certain medicines.  Maybe the person is on a medication that impairs their memory and their doctor might not even know this is a potential side effect. In these cases, when the medicine is stopped normal cognitive functioning can return.

In other occasions, mild cognitive impairment can be caused by chronic sleep issues, depression or other psychiatric disorders. Even elevated stress for long periods of time can lead to impaired cognitive abilities. In these cases, addressing the underlying issues that may be causing the MCI symptoms is important.

Even though some cognitive impairment can be temporary and linked to medications, it is not common to get a diagnosis of MCI and then return to non-MCI / “normal” status — that happens, but it is not the norm.

A diagnosis of MCI is concerning, but it is not a guarantee that you’re headed towards dementia. Most MCI remain stable… and around 10% convert to dementia each year.

The longer you live with a diagnosis of MCI the higher your chances are of converting to clinically recognized dementia.

Be part of the solution. Help scientists understand how to prevent dementia. Take the MindCrowd test today 👉 mindcrowd.org 

MindCrowd is a scientific study that gives researchers a set of data baselines about how normal, healthy brains perform at different ages.

MindCrowd cannot diagnose dementia or predict the risk for cognitive decline. By taking this quiz you will help researchers in the future to more properly evaluate Alzheimer’s patients and usher in a new era of precision aging.

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Can you Still Drive with MCI?

This is definitely a case-by-case decision that should be made in close consultation with your doctor. It depends on the level of impairment and which types of impairment are predominating. You can’t give a blank statement about driving, that’s an individual discussion with the physician.

Is There Treatment for Mild Cognitive Impairment?

There is no FDA-approved treatment for MCIs.

However, some of the drugs that are approved for use in Alzheimer’s disease patients may be helpful. Cholinesterase inhibitors (Aricept®, Exelon®, Razadyne®) and NMDA receptor antagonists (Namenda®) are the two classes of drugs that are approved for use in Alzheimer’s disease. They typically only work for a short period of time though.

Non-pharmaceutical approaches can demonstrate benefit in the MCI patient. One of the most common suggestions is to exercise regularly as exercise is known to improve brain health.

Measuring Cognitive Impairment: The 30 Question Cognitive Test or MMSE

The Mini–Mental State Examination (MMSE) test is one of the ways that memory is assessed in a clinical space. This is sometimes referred by people as the “30 Question Cognitive Test.”

This test is very simple for people who don’t have memory and thinking problems. The goal of this test is not to test your intelligence but to test and identify significant cognitive problems.

The Mini-Mental State Examination (MMSE) includes items that assess registration, attention and calculation, recall, language, and orientation.

The MMSE has to be administered by a professional. You cannot self-administer the MMSE. Your friends can’t give this memory test to you.

This needs to be done in a clinical space by a professional who has been trained in how to give the test and how to score the test.

There are specific ways in which this test has to be given.

In general, this test is a blunt way of testing someone’s memory. It functions as a screening test that could result in further assessment if necessary. Neurologists like it because it’s fast, pretty simple to give and it does a good job of picking out dementia and strong memory problems.


A certain percentage of people with MCI go on to eventually have Alzheimer’s disease, vascular dementia, or some other dementia type.

Not all individuals with mild cognitive impairment progress to dementia. Some people recover in full while others never progress but rather maintain their memory and thinking skills at this new, lower, level.

Thus, MCI is NOT necessarily a precursor to Alzheimer’s disease or any other dementia. It is a diagnosis that should be taken seriously and managed with the guidance of your physician.


Discover how it compares with others like you in 10 short minutes by playing the free online MindCrowd memory game.

And help scientists find new ways to protect our brains from memory loss as we age.

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Matt Huentelman is a neuroscientist and a human genetics researcher. His laboratory studies how the brain ages and explores various ways in which we can prevent brain aging and protect against diseases of the aging brain like Alzheimer’s disease. His lab is based at TGen in Phoenix, Arizona, and he is also the lead scientist for the MindCrowd project.

MindCrowd is an internet based study of the brain that anyone 18 years of age or older can join and it can be found at mindcrowd.org

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