Mild cognitive impairment (MCI) is a slight decline in one’s memory and/or one’s ability to think clearly. It is noticeable to the person experiencing it and to his or her loved ones. It is also measurable on cognitive tests.
Mild cognitive impairment is not considered a form of dementia, however, because it is not severe enough to interfere with a person’s daily routine or with the ability to function independently.
The Alzheimer’s Association claims that 10 to 20 percent of people over the age of 65 may have mild cognitive impairment (Alzheimer’s Association).
According to the Mayo Clinic, the causes of mild cognitive impairment are not clearly understood. The most current evidence suggests that MCI is often caused by lesser degrees of the same types of brain damage found in Alzheimer’s disease and other forms of dementia. These changes include
- beta-amyloid plaques with protein tangles
- dementia with Lewy bodies
- reduced blood flow to the brain
- damage caused by multiple small strokes
- shrinkage of parts of the brain associated with memory
- enlargement of fluid-filled spaces (ventricles)
- less use of glucose in key thinking regions
Mild cognitive impairment has two broad categories of symptoms. The first category primarily affects memory (for example, forgetting doctor’s appointments or not being able to recall the name of a good friend). This type of impairment is known as “amnestic MCI.”
The second category of symptoms have to do with the thought process itself—planning and completing a complex task like balancing one’s checkbook, for instance, or exercising good judgment in risky situations. This type of impairment is known as “nonamnestic MCI.”
Both types of symptoms may occur in the same individual.
According to the Alzheimer’s Association, a medical workup for MCI should include at least seven core areas of assessment (Alzheimer’s Association). No diagnosis of any kind of cognitive impairment should be made until all of the following tests have been completed:
- a thorough medical history, both to assess for a familial history of dementia and to identify any illnesses or medications that could be causing cognitive symptoms
- assessment of the individual’s ability to function independently
- input from those familiar with the individual to help catch symptoms the individual him or herself might miss
- a series of simple mental status tests
- a neurological exam performed in the physician’s office
- careful evaluation of mood and behavior, because mental illnesses like schizophrenia, bipolar disorder, and major depression can cause symptoms that mimic dementia
- blood tests to rule out infections
- brain imaging tests to confirm the diagnosis of MCI or dementia
No medications have been approved for use in those with mild cognitive impairment, but some lifestyle changes may help slow or even reverse disease progression. These include regular exercise, controlling cardiovascular risks (e.g., by stopping smoking, changing one’s diet to include fresh fruits and vegetables, whole grains, and lean proteins) and participating in mentally and socially stimulating activities (Alzheimer’s Association).
A study published in the British Journal of Psychiatry suggests that 60 to 65 percent of people with mild cognitive impairment will go on to develop clinical dementia. Most of the other study participants either withdrew or passed away without a diagnosis of dementia (Busse et al., 2006).
The chief complication associated with mild cognitive impairment, according to the National Institute on Aging, is developing Alzheimer’s disease or a related form of progressive dementia (National Institute on Aging).
Because so little is known about the causes of mild cognitive impairment, there are no definitive guidelines in place for its prevention. Some agencies suggest maintaining good cardiovascular health, but there is no evidence that this actually does prevent MCI.