Mild cognitive impairment (MCI)

Updated: 2024-02-13

Overview

Mild cognitive impairment (MCI) is the stage between the expected decline in memory and thinking that happens with age and the more serious decline of dementia. MCI may include problems with memory, language or judgment.

People with MCI may be aware that their memory or mental function has "slipped." Family and close friends also may notice changes. But these changes aren't bad enough to impact daily life or affect usual activities.

MCI may increase the risk of dementia caused by Alzheimer's disease or other brain disorders. But some people with mild cognitive impairment might never get worse. And some eventually get better.

Symptoms

The brain, like the rest of the body, changes with age. Many people notice they become more forgetful as they age. It may take longer to think of a word or to recall a person's name.

If concerns with mental function go beyond what's expected, the symptoms may be due to mild cognitive impairment (MCI). MCI may be the cause of changes in thinking if:

• You forget things more often.
• You miss appointments or social events.
• You lose your train of thought. Or you can't follow the plot of a book or movie.
• You have trouble following a conversation.
• You find it hard to make decisions, finish a task or follow instructions.
• You start to have trouble finding your way around places you know well.
• You begin to have poor judgment.
• Your family and friends notice any of these changes.

If you have MCI, you also may experience:

• Depression.
• Anxiety.
• A short temper and aggression.
• A lack of interest.

When to see a doctor

Talk to your health care provider if you or someone close to you notices you're having problems with memory or thinking. This may include trouble recalling recent events or having trouble thinking clearly.

Causes

Changes in brain structure with MCI and Alzheimer's disease

Changes in brain structure with MCI and Alzheimer's disease

Some changes in brain structure — such as the decrease in size of the brain's memory center (hippocampus) — are typical with aging. However, this reduction in size is greater in those with mild cognitive impairment and even more dramatic in people with Alzheimer's disease.

Brain shrinkage in MCI and Alzheimer's disease

Brain shrinkage in MCI and Alzheimer's disease

Dementia causes the brain to lose mass, especially in critical areas. Note the difference in size between a healthy brain (top), a mild cognitive impairment brain (middle) and an Alzheimer's disease brain (bottom).

There's no single cause of mild cognitive impairment (MCI), although MCI may be due to early Alzheimer's disease. There's no single outcome for the disorder. Symptoms of MCI may remain stable for years. Or MCI may progress to Alzheimer's disease dementia or another type of dementia. In some cases, MCI may improve over time.

MCI often involves the same types of brain changes seen in Alzheimer's disease or other forms of dementia. In MCI, those changes occur at a lesser degree. Some of these changes have been seen in autopsy studies of people with MCI.

These changes include:

• Clumps of beta-amyloid protein, called plaques, and tangles of tau proteins that are seen in Alzheimer's disease.
• Microscopic clumps of a protein called Lewy bodies. These clumps are associated with Parkinson's disease, dementia with Lewy bodies and some cases of Alzheimer's disease.
• Small strokes or reduced blood flow through brain blood vessels.

Brain-imaging studies show that the following changes may be associated with MCI:

• Decreased size of the hippocampus, a brain region important for memory.
• Increased size of the brain's fluid-filled spaces, known as ventricles.
• Reduced use of glucose in key brain regions. Glucose is the sugar that's the main source of energy for cells.

Risk factors

The strongest risk factors for MCI are:

• Increasing age.
• Having a form of a gene known as APOE e4. This gene also is linked to Alzheimer's disease. But having the gene doesn't guarantee that you'll have a decline in thinking and memory.

Other medical conditions and lifestyle factors have been linked to an increased risk of changes in thinking, including:

• Diabetes.
• Smoking.
• High blood pressure.
• High cholesterol.
• Obesity.
• Depression.
• Obstructive sleep apnea.
• Lack of physical exercise.
• Low education level.
• Lack of mentally or socially stimulating activities.

Complications

People with MCI have an increased risk — but not a certainty — of developing dementia. Overall, about 1% to 3% of older adults develop dementia every year. Studies suggest that around 10% to 15% of people with MCI go on to develop dementia each year.

Prevention

Mild cognitive impairment can't be prevented. But research has found some lifestyle factors may lower the risk of getting MCI. Studies show that these steps may help prevent MCI:

• Don't drink large amounts of alcohol.
• Limit exposure to air pollution.
• Reduce your risk of a head injury.
• Don't smoke.
• Manage health conditions such as diabetes, high blood pressure, obesity and depression.
• Practice good sleep hygiene and manage any sleep problems.
• Eat a healthy diet full of nutrients. Include fruits and vegetables and foods low in saturated fats.
• Stay social with friends and family.
• Exercise at a moderate to vigorous intensity most days of the week.
• Wear a hearing aid if you have hearing loss.
• Stimulate your mind with puzzles, games and memory training.

Diagnosis

No one test can confirm that someone has mild cognitive impairment (MCI). A diagnosis is made based on the information you provide and results of tests that can help clarify the diagnosis.

Many health care providers diagnose MCI based on criteria developed by a panel of international experts:

• Problems with memory or another mental function. People with MCI may have problems with memory, planning, following instructions or making decisions. A provider may confirm these issues with a family member or a close friend.
• Mental function that declines over time. This is revealed with a careful medical history. The change is confirmed by a family member or a close friend.
• Daily activities aren't affected. Although symptoms may cause worry, people with MCI are still able to live their lives as usual.
• Mental status testing shows mild level of impairment for age and education level. Health care providers often use a brief test such as the Short Test of Mental Status, the Montreal Cognitive Assessment (MoCA) or the Mini-Mental State Examination (MMSE). More detailed testing may help determine the degree memory is impaired. The tests also may reveal the types of memory most affected and whether other mental skills also are impaired.
• The diagnosis isn't dementia. The problems aren't severe enough to be diagnosed as Alzheimer's disease dementia or another type of dementia.

Neurological exam

As part of a physical exam, a health care provider may perform some basic tests that can reveal how well the brain and nervous system are working. These tests can help detect signs of Parkinson's disease, strokes, tumors or other medical conditions that can impair memory and physical function.

The neurological exam may test:

• Reflexes.
• Eye movements.
• Walking and balance.

Lab tests

Blood tests can help rule out physical problems that may affect memory. This can include not enough vitamin B-12 or thyroid hormone.

Brain imaging

An MRI or CT scan can check for a brain tumor, stroke or bleeding.

Mental status testing

Short forms of mental status testing can be done in about 10 minutes. The test will ask to name the date and follow written instructions.

Longer forms of tests can provide details about how someone's mental function compares with others of a similar age and education. These tests also may help identify patterns of change that offer clues about the cause of symptoms.

Treatment

Mild cognitive impairment is an active area of research. Clinical studies are being conducted to better understand the disorder and find treatments that may improve symptoms or prevent or delay dementia.

Alzheimer's drugs

The Alzheimer's medicine called cholinesterase inhibitors is sometimes given to people with MCI whose main symptom is memory loss. However, cholinesterase inhibitors aren't recommended for routine treatment of MCI. They haven't been found to affect progression to dementia, and they can cause side effects.

The Food and Drug Administration (FDA) has approved lecanemab (Leqembi) for people with Alzheimer's disease and MCI due to Alzheimer's disease. Not all people with MCI are expected to be eligible for the treatment, since only some have MCI due to Alzheimer's disease.

A phase 3 clinical trial found that the medicine slowed cognitive decline in people with early Alzheimer's disease. Lecanemab works by preventing amyloid plaques in the brain from clumping. This study was the largest so far to look at whether clearing clumps of amyloid plaques from the brain can slow the disease.

Lecanemab is given as an IV infusion every two weeks. Side effects of lecanemab include infusion-related reactions such as fever, flu-like symptoms, nausea, vomiting, dizziness, changes in heart rate and shortness of breath.

Also, people taking lecanemab may have swelling in the brain or may get small bleeds in the brain. Rarely, brain swelling can be serious enough to cause seizures and other symptoms. Also in rare instances, bleeding in the brain can cause death. The FDA recommends getting a brain MRI before starting treatment. It also recommends being monitored with brain MRIs during treatment for symptoms of brain swelling or bleeding.

People who carry a certain form of a gene known as APOE e4 appear to have a higher risk of these serious complications. The FDA recommends being tested for this gene before starting treatment with lecanemab.

If you take a blood thinner or have other risk factors for brain bleeding, talk to your health care professional before taking lecanemab. Blood-thinning medicines may increase the risk of bleeds in the brain.

More research is being done on the potential risks of taking lecanemab. Other research is looking at how effective lecanemab may be for people at risk of Alzheimer's disease, including people who have a first-degree relative, such as a parent or sibling, with the disease.

Treating reversible causes of MCI: Stopping certain medicines

Certain medicines can cause side effects that affect thinking. These side effects are thought to go away once the medicine is stopped. Discuss any side effects with your health care provider and never stop taking your medicine unless your provider tells you to do so. These medicines include:

• Benzodiazepines, used to treat conditions such as anxiety, seizures and sleep disturbances.
• Anticholinergics, which affect chemicals in the nervous system to treat many different types of conditions.
• Antihistamines, often used to manage allergy symptoms.
• Opioids, often used to treat pain.
• Proton pump inhibitors, often used to treat reflux or gastroesophageal reflux disease (GERD).

Treating reversible causes of MCI: Other conditions

Other common conditions besides MCI can make you feel forgetful or less mentally sharp than usual. Treating these conditions can help improve your memory and overall mental function. Conditions that can affect memory include:

• High blood pressure. People with MCI tend to be more likely to have problems with the blood vessels inside their brains. High blood pressure can worsen these problems and may cause memory loss. Your health care provider will monitor your blood pressure and recommend steps to lower it if it's too high.
• Depression. When you're depressed, you often feel forgetful and mentally "foggy." Depression is common in people with MCI. Treating depression may help improve memory, while making it easier to cope with the changes in your life.
• Sleep apnea. In this condition, your breathing stops and starts several times while you're asleep, interfering to get a good night's rest. Sleep apnea can make you feel very tired during the day, forgetful and not able to focus. Treatment can improve these symptoms and make you more alert during the day.

Lifestyle and home remedies

Study results have been mixed about whether diet, exercise or other healthy lifestyle choices can prevent or reverse cognitive decline. Regardless, these healthy choices promote good overall health and may play a role in good cognitive health.

• Regular physical exercise has known benefits for heart health. It also may help prevent or slow cognitive decline.
• A diet low in fat and rich in fruits and vegetables is another heart-healthy choice that also may help protect brain health.
• Omega-3 fatty acids also are good for the heart. Most research on omega-3s that shows a possible benefit for brain health looks at how much fish people eat.
• Keeping your brain active may prevent cognitive decline. Studies have shown that playing games, playing an instrument, reading books and other activities may help preserve brain function.
• Being social may make life more satisfying, help preserve mental function and slow mental decline.
• Memory training and other cognitive training may help improve your function.

Alternative medicine

Some supplements — including vitamin E, ginkgo and others — have been suggested to help prevent or delay mild cognitive impairment. However, more research is needed in this area. Talk to your health care provider before taking supplements as they can interact with your current medicines.

Preparing for an appointment

You're likely to start by seeing your primary care provider. If your provider suspects that you have cognitive changes, you may be referred to a specialist. This specialist may be a neurologist, psychiatrist or neuropsychologist.

Because appointments can be brief and there's often a lot to talk about, it's good to be well prepared. Here are some ideas to help you get ready for your appointment and know what to expect from your provider.

What you can do

• Be aware of any pre-appointment restrictions. When you make your appointment, ask if you need to fast for bloodwork or if you need to do anything else to prepare for diagnostic tests.
• Write down all of your symptoms. Your health care provider will want to know details about what's causing your concern about your memory or mental function. Make notes about some of the most important examples of forgetfulness or other lapses you want to mention. Try to remember when you first started to suspect that something might be wrong. If you think your difficulties are getting worse, be ready to explain why.
• Take along a family member or friend, if possible. Corroboration from a relative or trusted friend can play a key role in confirming that your memory loss is apparent to others. Having someone along also can help you remember all the information provided during your appointment.
• Make a list of your other medical conditions. Your provider will want to know if you're currently being treated for diabetes, heart disease, past strokes or any other conditions.
• Make a list of all your medicines. Your provider will want to know about any medicines you take. That includes prescription medicines, medicines available without a prescription, vitamins or supplements.

Questions to ask your doctor

Because time with your health care provider is limited, writing down a list of questions will help you make the most of your appointment. List your questions from most pressing to least important in case time runs out. For cognitive changes, some questions to ask your provider include:

• Do I have a memory problem?
• What's causing my symptoms?
• What tests do I need?
• Do I need to see a specialist? What will that cost? Will my insurance cover it?
• Are treatments available?
• Are there any clinical trials of experimental treatments I should consider?
• Should I expect any long-term complications?
• Will my new symptoms affect how I manage my other health conditions?
• Do I need to follow any restrictions?
• Is there a generic alternative to the medicine you're giving me?
• Do you have any brochures or other printed material I can take home with me? What websites do you recommend?

In addition to the questions you've prepared ahead of time, don't hesitate to ask your health care provider to clarify anything you don't understand.

What to expect from your doctor

Your provider also is likely to have questions for you. Being ready to respond may free up time to focus on any points you want to talk about in-depth. Your provider may ask:

• What kinds of memory issues are you having? When did they first appear?
• Are they steadily getting worse, or are they sometimes better and sometimes worse?
• Do you feel any sadder or more anxious than usual?
• Have you noticed any changes in the way you react to people or events?
• Have you noticed any changes in how well or how long you sleep? Do you snore?
• Do you have more energy than usual, less than usual or about the same?
• What medicines are you taking? Are you taking any vitamins or supplements?
• Do you drink alcohol? How much?
• What other medical conditions are you being treated for?
• Have you noticed any trembling or trouble walking?
• Are you having any trouble remembering your medical appointments or when to take your medicine?
• Have you had your hearing and vision tested recently?
• Did anyone else in your family ever have memory trouble? Was anyone ever diagnosed with Alzheimer's disease or dementia?