Mild Cognitive Impairment | Alzheimer's Prevention Registry

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February 1, 2016

Mild Cognitive Impairment

By Banner Alzheimer's Institute


In your doctor’s office or even on a recent news story you may have heard the term, MCI, or mild cognitive impairment. Like other medical jargon, this term can be confusing and is sometimes used and described in different ways by medical professionals. This article aims to help define mild cognitive impairment and understand how it is evaluated, diagnosed, and what this may mean for you and/or a family member or friend.

Mild cognitive impairment (MCI) was first described as a transition state between normal cognition (memory and thinking) and dementia, particularly in reference to memory changes seen prior to Alzheimer’s disease. Over the past 15 years or so, the concept of MCI has been studied, debated, and clarified. There are multiple ways that medical providers understand and define MCI. The basic definition is impairment in thinking skills that goes beyond normal age-related cognitive changes but does not meet criteria for dementia. That is, as an individual ages, we expect changes in some thinking skills (e.g., learning and memory, speed of thinking) to decline over time. This is usually called age-associated cognitive changes or what some people consider “normal aging.” However, with MCI, individuals demonstrate loss in skills compared to others their own age. In addition there may be a decline in the person’s abilities greater than expected given prior level of cognitive functioning. As discussed in the January 2016 edition of the BAI Beacon newsletter, dementia means that there are changes in thinking abilities that interfere with a person’s independence in everyday activities. One of the main differences between dementia and MCI, is that in MCI, individuals can experience mild changes in everyday activities. However, the person’s cognitive changes do not significantly interfere with the ability to complete everyday life skills, such as shopping, cooking, cleaning, completing hobbies, and managing money, appointments, and medications.

To help medical providers be more specific when describing cognitive impairment, several MCI subtypes have been described based on different areas (i.e., domains) of thinking. But first, it is important to understand the main domains of thinking skills that medical providers look at when MCI is considered. These domains generally include:

  • Memory: new learning, recall, and retrieval of recent information
  • Language: ability to come up with words, name items, understand others
  • Attention: concentration, ability to focus and stay on task
  • Visuospatial abilities: understand and interpret spatial relationships, constructional skills
  • Executive functioning: problem solving, reasoning, sequencing, control over behavior

These cognitive domains can be assessed in many ways. Brief cognitive screenings using the Mini-Mental Status Examination (MMSE), Montreal Cognitive Assessment (MoCA), and/or other brief tests can be done in your doctor’s office. They are helpful for the doctor to look for changes in one of these domains if MCI is suspected. Nevertheless, many times these cognitive screenings are not conclusive and physicians order a neuropsychological evaluation. A neuropsychological evaluation can provide more in depth testing of these skills. Specifically, a neuropsychologist can measure the extent of a patient’s cognitive strengths and weaknesses in different domains. The neuropsychologist will compare that person’s performance on tests to other cognitively normal healthy adults who are of a similar age.

The multiple subtypes of MCI are based on the cognitive domains described. First, MCI can be split into amnestic or non-amnestic subtypes. Amnestic and non-amnestic refers to whether or not there is a problem in learning and/or memory skills. Subtypes are then further divided by how many different domains of thinking are impaired and classified into single domain or multi-domain (i.e., multiple areas). In single domain MCI, there is only one major domain of thinking impaired. In multi-domain MCI, there is impairment in two or more major domains of thinking. Therefore, one can have single domain, amnestic MCI, where memory is the only domain of thinking impaired. In multi-domain amnestic MCI, memory and at least one other domain of thinking is impaired. In comparison, one can have single domain, non-amnestic MCI, where one domain other than memory (e.g., attention) is impaired alone. Likewise, a person could have multi-domain non-amnestic MCI, where at least two non-memory domains (e.g., attention and executive functioning) are impaired.

The reason MCI and these subtypes were originally created was to help describe, detect, and attempt to treat cognitive changes earlier. This is very important in those with an underlying neurodegenerative condition (i.e., a condition that affects brain cells and gets progressively worse over time) prior to progression to dementia. Thus, many times MCI reflects early cognitive changes that occur as part of an underlying condition that will later progress to dementia. The type of dementia can include Alzheimer’s disease (AD), Dementia with Lewy Bodies (DLB), Vascular dementia (VaD), Frontotemporal dementia (FTD), or other dementias.

Approximately 14-18% of people over the age of 70 have been diagnosed with MCI. Amnestic MCI is the most common form. It is about twice as common as nonamnestic subtypes, occurring in 5-6% of older adults (>70 years of age) per year. A diagnosis of MCI increases the risk for later developing dementia. But, some individuals will never progress to dementia. Up to 15% of those diagnosed with MCI will progress to dementia each year, with up to 60-65% of individuals with MCI progressing to dementia in his/her lifetime. In contrast, approximately 1-2% of older adults without MCI are diagnosed with dementia per year. Amnestic MCI usually progresses to the most common form of dementia, Alzheimer’s disease. Those with non-amnestic forms of MCI may be at lower risk to later develop dementia. Nevertheless, they are still at risk to progress to other syndromes, such as DLB or FTD, where changes in executive functioning, attention, and/or behavior are usually impacted more than learning and memory.

It is important to remember that cognitive impairment can be related to a number of different factors - not always an underlying neurodegenerative syndrome, such as Alzheimer’s disease. It can be difficult for medical providers to know the reason for cognitive changes. Examples include:

  • Psychiatric changes (e.g., depressed mood, anxiety);
  • Medical and/or neurological conditions (e.g., sleep apnea; stroke; significant sleepiness/fatigue; urinary tract infections; low thyroid);
  • Treatment and/or medication effects (e.g., chemotherapy, side effects or interactions of medications) can also impact cognition.

Furthermore, some can have both an underlying neurodegenerative condition along with a condition described above. Therefore, it makes the diagnosis more difficult for medical providers. This is why a full medical work-up usually includes a physical exam, review of background and medical history, laboratory tests, brain imaging, and cognitive testing. MCI is still based on the clinical judgment of the medical provider. Medical followup and allowing for the passage of time, is critical in aiding in accurate diagnosis.

Given that there are different subtypes and multiple potential varied causes of MCI, including neurodegenerative illnesses, treatment options vary. Your physician may recommend changes and/or treatment to limit the possible effects of other potential causes of MCI. This can include controlling for side effects of medications, other medical conditions, or treatment of depression/anxiety. If a neurodegenerative process, such as Alzheimer’s disease is suspected, your physician may consider initiation of treatment with medications, such as Aricept. Moreover, individuals diagnosed with MCI may also be a candidate for one of several clinical trials and research studies at BAI/BSHRI examining MCI.