Mild cognitive impairment: ten years later

Abstract

In the past 10 years, there has been a virtual explosion in the literature concerning the construct of mild cognitive impairment. The interest in this topic demonstrates the increasing emphasis on the identification of the earliest features of cognitive disorders such as Alzheimer disease and other dementias. Mild cognitive impairment represents the earliest clinical features of these conditions and, hence, has become a focus of clinical, epidemiologic, neuroimaging, biomarker, neuropathological, disease mechanism, and clinical trials research. This review summarizes the progress that has been made while also recognizing the challenges that remain.

Figure 1

Number of publications with “mild cognitive impairment” in the title or abstract from 1990 through 2008.

Figure 2

Current flowchart for the diagnosis of mild cognitive impairment (MCI) and its subtypes. Reprinted with permission from Blackwell Publishing.

Figure 3

Presumed outcome of the subtypes of mild cognitive impairment (MCI) when combined with the presumed pathogenesis. Adapted from: Petersen. Reprinted with permission from Oxford University Press, Inc. AD indicates Alzheimer disease; depr, depression; DLB, dementia with Lewy bodies; FTD, frontotemporal dementia; NA, not applicable; VaD, vascular dementia.

Figure 4

Hypothetical temporal ordering of neuropathological processes in the course of Alzheimer disease and corresponding imaging in biomarker measures. Aβ indicates amyloid β; CSF, cerebrospinal fluid; FDG PET, fludeoxyglucose F 18 positron emission tomography; MCI, mild cognitive impairment; MRI, magnetic resonance imaging.