Mild Cognitive Impairment
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- Mild cognitive impairment (MCI) is defined as significant cognitive impairment in the absence of dementia, as measured by standard memory tests:
- Concern regarding change in cognition
- Preservation of independence in functional activities (ADLs)
- Impairment in ≥1 cognitive domains (attention, executive dysfunction, memory, visuospatial, language) (1)
- Other terms used in the literature relating to MCI: isolated memory impairment; cognitive impairment not dementia (CIND); predementia; mild cognitive disorder; age-associated memory impairment; age-related cognitive decline; benign senescent forgetfulness. Some of these conditions do not progress to dementia (i.e., benign senescent forgetfulness, age-associated memory impairment, age-related cognitive decline). DSM-5 mentions “mild neurocognitive disorder” (NCD) which may be a precursor to Alzheimer disease and has many of the same features as MCI (2).
- Annual rates of conversion of MCI to dementia are 2–15% in the elderly.
- Predominant sex: male > female (3)
- Predominant age:
- Higher in older persons and in those with less education
- 12 to 15/1,000 person-years in those age ≥65 years
- 54/1,000 person-years in those age ≥75 years
- MCI is more prevalent than dementia in the United States.
- 3–5% for those age ≥60 years
- 15% for those age ≥75 years
Etiology and Pathophysiology
- Subtypes of MCI:
- Single-domain amnestic
- Multiple-domain amnestic
- Nonamnestic single-domain
- Nonamnestic multiple-domain
- The amnestic subtype is higher risk for progression to Alzheimer disease (4).
- Vascular, degenerative, traumatic, metabolic, psychiatric, or a combination
Apolipoprotein (APO) E4 genotype: Various pathways exist leading to amyloid accumulation and deposition thought to be associated with dementia.
- Cerebrovascular disease
- Sleep apnea
- APO E4 genotype
Commonly Associated Conditions
See “Risk Factors” (5).