Mild Cognitive Impairment: A silent and late detection disorder

ABSTRACT

Mild cognitive impairment (MCI) was first described some two decades ago to describe a usual clinical situation: older persons that significantly underperformed in cognitive tests but were functionally able to perform normally. This fact had been described for long and received many names (benign senescent forgetfulness, age associated memory impairment and many other).

Petersen defined MCI as a decline in cognitive functioning that exceeds the expected level given the patient’s age and education in one or more cognitive domains, including complex attention, executive functions, language, learning and memory, perceptual-motor domain, and social cognition. Research in MCI increased rapidly, showing that this was an intermediate status between normal cognition and dementia that could potentially open the door to early detection of dementing disorders, so MCI received an ICD-9 code. Persons with MCI may progress to dementia, revert to normal cognition, or remain at MCI. Variants of MCI have been described, the most relevant probably the amnestic subtype (it predicts progression to Alzheimer’s disease) and the non-amnestic/multiple deficits subtypes, which
predict progression to other dementias, including vascular dementia). Rates of progression are shown in this figure.


Cognitive assessment of MCI is still not fully standardized, with different groups using different tools both in research and clinical settings. MCI remains underdiagnosed, especially among older adults. As MCI is part of the dementia continuum many recommendations for the diagnosis of MCI have been included in dementia clinical practice guidelines. From a geriatric point of view, research is looking to the relations between MCI and the concept of cognitive and physical frailty.

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