Mild cognitive impairment
Mild cognitive impairment (MCI) is a clinical diagnosis of measurable cognitive decline with preserved daily function, requiring a reversible-cause workup (TSH, vitamin B12, structural imaging) before counseling. No medication is approved to treat MCI or prevent progression; management is exercise, risk-factor control, and monitoring, since annual dementia conversion risk is 5-15%.
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What this article covers
- Overview
Intermediate cognitive stage: mild cognitive impairment (MCI) is a clinical diagnosis for patients with measurable cognitive decline who do not meet criteria for dementia, sitting between normal age-related change and overt dementia.
- Epidemiology
Common in older adults: population-based studies of adults age 70 and older report an MCI prevalence of 14% to 18%.
- Risk factors
Age: the single strongest risk factor; prevalence rises through the seventh, eighth, and ninth decades.
- Pathophysiology
Heterogeneous substrate: MCI is a clinical syndrome, not a single disease; underlying pathology varies by subtype and may include early Alzheimer neuropathology (amyloid-beta plaques, neurofibrillary…
- Clinical features
Diagnostic criteria (the disease is clinically diagnosed): a subjective report, from the patient or a reliable informant, of decline in cognitive ability; objective evidence of impairment on…
- Differential diagnosis
Alzheimer disease: progressive memory-predominant dementia with loss of functional independence (impaired instrumental or basic activities of daily living), unlike the preserved function of MCI.
- Diagnosis
MCI is diagnosed clinically when a subjective cognitive complaint (from patient or informant) is confirmed by objective impairment on standardized cognitive testing, with preserved functional…
- Management
First, treat any identified reversible cause: correct thyroid dysfunction, replace vitamin B12 deficiency, treat depression, discontinue or substitute cognitively impairing medications (especially…
- Complications
Progression to dementia: the primary long-term risk, occurring in 5% to 15% of patients with MCI per year, most often to Alzheimer disease from the amnestic subtype.
- Prognosis
Variable trajectory: a meaningful proportion of patients with MCI remain stable or revert to normal cognition, while others progress to dementia at 5% to 15% per year.
- Prevention
Exercise is the most important modifiable factor for preventing progression of cognitive impairment: 150 to 300 minutes/week of moderate-intensity aerobic activity, or 75 to 150 minutes/week of…
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