What is Mild Cognitive Impairment? Symptoms, Causes, and Recovery

How is mild cognitive impairment different from dementia? Can it be reversed? MindCrowd’s lead neuroscientist and human genetics researcher, Dr. Matt Huentelman, breaks down the answers.

Many people experience memory difficulties, and forgetfulness as they age. Is this mild cognitive impairment (MCI)? Is this a diagnosable condition? And if so, how do we know?

The difference from normal memory lapse episodes can be tricky to grasp. What distinguishes MCI is that the changes are measurable compared to peers, even if daily life is largely intact.

Everyone forgets things sometimes, but with MCI these lapses happen more often than normal for their age.

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.

Those would be some of the cognitive warning signs.

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 is a problem, that affects our daily life. Forgetting where we left our keys for a few hours, that’s normal.

How is MCI Diagnosed?

Sometimes, a family member or friend brings a person to the doctor, worried about memory or thinking changes. The patient may insist that they are fine — but subtle cognitive changes are noticeable to those who know them best.

Other times, the person notices changes themselves and wants to be proactive. They may have a family history of Alzheimer’s, which increases risk—but it’s not written in the stars. Ruling out other causes is a great first step.

Therefore, mild cognitive impairment is primarily identified in people who already have concerns about their cognition. Their memory or thinking abilities have declined over time but this does not impact their day-to-day activities.

The Diagnostic Process

They go to their clinician – this could be a physician, neurologist, or psychologist – and share their concerns. The doctor will start with a detailed history and functional review.

Next, the health care professional assesses cognitive function using standardized memory and thinking tests.

When tested, an MCI patient’s score may show a mild level of impairment for their age and education. However, it won’t rise to the clinical definition of dementia.

After the cognitive test, the clinician may:

• Order blood tests to check for vitamin deficiencies, thyroid problems, or other conditions that can affect cognition
• Request brain imaging in some cases to rule out structural causes
• Administer additional memory tests

The results for a person with MCI are typically not significant enough to be labeled dementia. A diagnosis usually requires careful clinical judgment by your doctor, taking all these factors into account. ☜

At what Age does Mild Cognitive Impairment Start?

This is different for each person. About 15% of people over age 65 meet the criteria for MCI, according to the American Academy of Neurology.

What are the Risk Factors?

Dr. Lee Ryan is a world-renowned expert in memory and cognitive aging. She is Director of the Brain Imaging Center at the U of A and Bio5.

She shares some common factors that can contribute to memory problems. These include:

You can clearly see that many of these are reversible and don’t necessarily indicate MCI.

How Fast does Mild Cognitive Impairment Progress?

This is also different for each person. We don’t yet have reliable ways to predict how fast MCI is going to progress.

This question is usually about how long someone has before developing Alzheimer’s. Or how long it might take to 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.

(We’ll explain what amnestic MCI means later in this article.)

However, progression can be shorter or longer than this range.

If the MCI is caused by medication use, recovery back to normal can be rapid. It can occur over the course of a few months.

However, this can depend on how long the medication was taken and how long it remains in the body after the last dose. Always talk to your doctor before stopping any medication. Your doctor will evaluate ways of managing this with you.

Is There Treatment for Mild Cognitive Impairment?

There is no FDA-approved treatment for MCIs.

However, some drugs approved for use in Alzheimer’s disease patients may be helpful. These include:

• Cholinesterase inhibitors (Aricept®, Exelon®, Razadyne®)
• NMDA receptor antagonists (Namenda®)

They typically only work for a short period 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.

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

When examining the brain of a person who died with an MCI diagnosis, it often shows changes seen in 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, examining the brains of people with MCI reveals a whole array of changes. Some are seen in normal aging, while others are seen in dementia patients.

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, which can form Lewy bodies. These are associated with Parkinson’s disease and Lewy Body dementia
• small strokes or reduced blood flow in brain blood vessels caused by 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 every patient is different, so these are broad patterns rather than hard rules.

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 looked at hundreds of people’s brains in each group, the average level of amyloid plaques would be:

Small Strokes or Cerebrovascular Disease

Mini strokes, blood leakage, and other cerebrovascular changes can be related to small vessel disease in the brain. Some strokes can be seen with brain imaging. On MRI, these often appear as white matter hyperintensities (WMHs).

Significant strokes are generally caught when a person is alive because they cause noticeable symptoms.

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

The MCI group usually falls between normal aging and dementia patients with regards to these blood vessel changes.

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

Ventricle Enlargement: The Brain’s Space-Filling Response

The ventricles circulate cerebrospinal fluid (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 — spaces or cavities filled with this fluid.

When large numbers of cells die, the overall brain tissue shrinks. Because the brain and spinal cord are a closed system, the ventricles expand to compensate for this tissue loss. 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 they’re closely linked.

Often, both of them are very obvious. As the tissue shrinks, the CSF expands.

What is the Difference between MCI and Dementia?

Both MCI and dementia are characterized by objective evidence of cognitive impairments. This means that we can measure and quantify their problems with memory and thinking.

The main difference is that dementia interferes with daily activities, while mild cognitive impairment does not.

Another way to put it: based on your test scores, MCI falls below the range of the memory scores for dementia. Think of it like lab results: from this value to this value is considered MCI, and beyond that range, it’s classified as dementia.

Are There Types of MCI?

Yes. 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.

Let’s Explore Mild Cognitive Impairment with Memory Loss (Amnestic MCI)

In amnestic MCI memory loss is the primary symptom, making it look more like early Alzheimer’s disease.

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

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.

Therefore, 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. And their doctor may not even know it’s 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 can lead to impaired cognitive abilities. In these cases, addressing the underlying issues that may be causing the MCI symptoms is important.

It is not common to get a diagnosis of MCI and then return to non-MCI / “normal” status. Even if the cognitive impairment was temporary and linked to medications. It 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 of converting to clinically recognized dementia.

Measuring Cognitive Impairment: The 30 Question Cognitive Test or MMSE

The Mini–Mental State Examination (MMSE) test is one way to assess memory in a clinical space. Sometimes people call it the “30 Question Cognitive Test.”

The goal of the test isn’t to measure your intelligence but to identify significant cognitive problems. The Mini-Mental State Examination (MMSE) includes items that assess registration, attention and calculation, recall, language, and orientation.

There are specific rules for administering this test. The MMSE must be administered by a professional who has been trained in how to give the test and how to score the test. It must be conducted in a clinical setting.

You cannot self-administer the MMSE, and your friends can’t give this memory test to you.

This test is very easy for people who don’t have memory and thinking problems.

In general, the MMSE is a blunt tool for testing someone’s memory. It functions as a screening test that may lead to further assessment if necessary. Neurologists like it because it’s fast, fairly easy to give, and does a good job of picking out dementia and strong memory problems.

In summary, 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.

• Related Read: 🧠 Is it MCI or just “Brain Fog”?

Many people experienced a “cognitive haze” during social isolation and lockdown. Discover what Dr. Matt Huentelman found about why isolation impacts our memory: Lockdown Brain Fog & Social Isolation

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