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What Is Mild Cognitive Impairment?

Updated on March 12, 2021
Medically reviewed by
Jennifer Davis, Ph.D., ABPP-CN
Article written by
Brooke Dulka, Ph.D.

  • Mild cognitive impairment (MCI) is a stage between normal age-related cognitive decline and Alzheimer’s or related neurodegenerative diseases.
  • MCI and Alzheimer’s disease can share similar biological causes.
  • MCI has the potential of progressing to Alzheimer’s dementia.

If you have grown more forgetful with age, know that you are not alone. But what separates normal, everyday forgetfulness from serious memory disorders associated with the aging brain? There is a stage between normal cognitive aging and more serious states of memory decline, such as Alzheimer’s disease. This stage is called mild cognitive impairment, or MCI.

“Mild cognitive impairment is a general diagnosis, which reflects a change in someone's thinking abilities that are not necessarily severe enough to impact a person’s ability to complete their everyday activities,” explained Dr. Jennifer Davis, a clinical neuropsychologist at Brown University in Rhode Island. Dr. Davis specializes in Alzheimer’s disease and related conditions.

A recent global analysis by COSMIC, an international memory consortium, estimated that about 6 percent of individuals over 60 have MCI. That’s roughly 4 million people in the United States.

Mild Cognitive Impairment Types

There are two types of MCI: amnestic MCI and nonamnestic MCI. MCI can also be linked to medical conditions and mental health issues unrelated to Alzheimer’s.

Amnestic MCI

Amnestic MCI primarily affects memory and the ability to remember important information a person would normally recall. This can include things like forgetting appointments, conversations, or recent events.

Nonamnestic MCI

Nonamnestic is the type of MCI that affects thinking and problem-solving. This can include issues with visual perception, the inability to make sound judgements, and difficulty remembering the sequence of steps required to finish a task.

Causes of Mild Cognitive Impairment

There is no single cause of MCI. “There are many reasons for which someone could have mild cognitive impairment,” Dr. Davis said. “It could be due to early Alzheimer's disease, but it could also be due to a host of other things.” Other possible causes include other forms of dementia, untreated depression, thyroid disorders, or concussion, Dr. Davis explained.

Research also suggests MCI can be associated with the same types of brain changes seen in the early stages of Alzheimer’s disease. This is why MCI is often thought of as an intermediate step between normal cognitive aging and Alzheimer’s.

Although researchers still don’t know how to prevent Alzheimer’s, they have made steps toward understanding its causes. It comes down to important changes in the brain. Many of the changes in the brain associated with Alzheimer’s are also associated with mild cognitive impairment.

Brain changes found in some individuals with MCI include:

Beta-amyloid proteins — The buildup of beta-amyloid proteins (plaques) is greater in individuals with MCI and memory decline.
Lewy body proteins — This protein clumping is found in some people with MCI.
Stroke — When the brain’s blood supply is interrupted or reduced, a stroke occurs. Strokes can also happen before the onset of MCI.
Brain atrophy — Shrinkage (or atrophy) of the hippocampus in the brain is common in people with MCI.
Enlarged ventricles — Ventricles are hollow spaces inside the brain that contain cerebrospinal fluid. In cases of MCI, these ventricles are bigger due to atrophy in the brain. This is particularly true among people with MCI who go on to develop Alzheimer’s.

MCI Symptoms

Sometimes it may be difficult to distinguish between normal signs of aging and symptoms that may indicate a more serious problem. In normal aging, it isn’t uncommon to forget someone’s name or misplace keys. However, when normal, age-related memory decline turns into frequently forgetting important information or getting lost in a familiar place, MCI may be developing.

In general, memory-related symptoms of MCI include:

Forgetting things more often than before
Forgetting important events, such as appointments or social events
Losing your train of thought or forgetting what is going on in conversations or movies
Feeling overwhelmed by decision-making, planning, or understanding instructions
Starting to have trouble finding your way or getting lost in familiar environments

Along with memory problems, other common symptoms of MCI include difficulties with the following:

Decision-making
Agitation
Impulsivity
Disinhibition
Irritability
Sleep problems
Anxiety
Depression

MCI Diagnosis

When your family members and close friends begin to notice memory lapses or other issues, this can indicate you are experiencing memory loss and may have MCI. A doctor can test thinking, memory, and language performance to see if you have signs of MCI. Your doctor also may suggest seeing another medical specialist for more testing, such as brain imaging.

It is important to remember that early diagnosis is critical because it can serve as a warning sign for Alzheimer's or other degenerative diseases, such as Parkinson’s disease or dementia with Lewy bodies. Read more about the benefits of early diagnosis and MCI.

Treatment Options

Currently, there are no drugs approved by the U.S. Food and Drug Administration (FDA) for the treatment of MCI, and the results of clinical trials have been mixed. However, there are some prescription drugs that could show promise for slowing the progression of MCI to conditions such as Alzheimer's.

“Right now the standard of care is actually not to treat with our available medications, because it doesn't necessarily slow progression or conversion from MCI to mild dementia,” Dr. Davis noted.

Dr. Davis explained that lifestyle behaviors like healthy diet and exercise can help slow down memory decline. She also explained that activities like socializing with others can strongly benefit cognitive function. Learn more about improving memory health.

Although agencies such as the National Institute on Aging are diligently working on finding ways to address MCI, more research is needed to figure out the exact causes of MCI and the most effective way to treat it.

You Are Not Alone: Finding Support for Mild Cognitive Impairment

If you or a loved one has MCI, know that you are not alone. Nearly 74,000 myALZteam members can relate to your experience.

How does MCI affect your life? What helps you or your loved one feel better? Share your tips and experiences in a comment below or on myALZteam. You'll be surprised how many community members have similar stories.

References
  1. Mild cognitive impairment: disparity of incidence and prevalence estimates — Alzheimer's & Dementia
  2. The prevalence of mild cognitive impairment in diverse geographical and ethnocultural regions: The COSMIC collaboration — PLOS One
  3. The Differentiation of Amnestic Type MCI from the Non-Amnestic Types by Structural MRI — Frontiers in Aging Neuroscience
  4. Differences Between Women and Men in Incidence Rates of Dementia and Alzheimer’s Disease — Journal of Alzheimer’s Disease
  5. Sex differences in the prevalence and incidence of mild cognitive impairment: A meta-analysis — Ageing Research Reviews
  6. NIA-AA Research Framework: Toward a biological definition of Alzheimer’s disease — Alzheimer’s & Dementia
  7. The association of Aβ amyloid and composite cognitive measures in healthy older adults and MCI — International Psychogeriatrics
  8. Prodromal clinical manifestations of neuropathologically confirmed Lewy body disease — Neurobiology of Aging
  9. Cognitive impairment after lacunar stroke: systematic review and meta-analysis of incidence, prevalence and comparison with other stroke subtypes — Journal of Neurology, Neurosurgery & Psychiatry
  10. 3D comparison of low, intermediate, and advanced hippocampal atrophy in MCI — Human Brain Mapping
  11. Shape abnormalities of subcortical and ventricular structures in mild cognitive impairment and Alzheimer's disease: Detecting, quantifying, and predicting — Human Brain Mapping
  12. Early Diagnosis of Alzheimer’s Disease: Is MCI Too Late? — Current Alzheimer Research
  13. Neuropsychiatric symptoms in MCI subtypes: the importance of executive dysfunction — International Journal of Geriatric Psychiatry
  14. Ketogenic diet, high intensity interval training (HIIT) and memory training in the treatment of mild cognitive impairment: A case study — Diabetes and Metabolic Syndrome
  15. Management of mild cognitive impairment (MCI): The need for national and international guidelines — The World Journal of Biological Psychiatry
  16. Memantine improves semantic memory in patients with amnestic mild cognitive impairment: A single-photon emission computed tomography study — Journal of International Medical Research
All updates must be accompanied by text or a picture.
Jennifer Davis, Ph.D., ABPP-CN is a clinical neuropsychologist specializing in Alzheimer's disease and related disorders. Learn more about her here.
Brooke Dulka, Ph.D. is a freelance science writer and editor. She received her doctoral training in biological psychology at the University of Tennessee. Learn more about her here.

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