A Multifactor Approach to Mild Cognitive Impairment

Taha Qarni, BHSc; Arash Salardini, MD

Disclosures

Semin Neurol. 2019;39(2):179-187. 

In This Article

Abstract and Introduction

Abstract

Mild cognitive impairment (MCI) represents an intermediate stage between normal cognition and dementia. Individuals with MCI are at increased risk of conversion to dementia, and the rate of progression of MCI to dementia is dependent on age, gender, and education. MCI may be diagnosed using neuropsychological criteria using cut-offs representing decrements in cognition, or using criteria to assess for a decline in functional status. The ability to determine the status of dementia-related biomarkers has allowed for better staging and prognostication in different forms of MCI. MCI is now recognized as a significant target stage for future therapies. These future therapies aim to reduce the rate of conversion of individuals with MCI to dementia. In this article, we review different conceptions of MCI, the diagnosis and prognostication of MCI, and presently available management approaches for this condition.

Introduction

Mild cognitive impairment (MCI) denotes problems with memory, attention, or other cognition, which are greater than that which would be expected from normal aging but not enough to interfere with daily functioning. MCI is common in the population above the age of 60, with an estimated prevalence of between 7 and 25%.[1,2] This wide difference in prevalence may be related to using different diagnostic criteria. The risk of MCI is greater with increasing age, male gender, and lower education.[3–6]

The idea that individuals go through an intermediate stage between normal cognition and dementia has a long history. It initially developed as a diagnostic category for determining the requisite level of care in the Montreal Hebrew old people's home in the 1950s under the name of benign senescent forgetfulness.[7] This nomenclature entered mainstream use after publications by Kral on this topic. Various other terms, with variable semantic and definitional vagueness, were subsequently used to include normal age-related cognitive decline, age-associated memory impairment, age-consistent memory impairment, and late-life forgetfulness.[8]

By the 1980s, better clinical measures of functioning were invented which added greater rigor to the study of cognitive impairment. The two most important ones were the Global Deterioration Scale (GDS) and the Clinical Dementia Rating (CDR). The term "mild cognitive impairment" was coined by Reisberg and others in 1988 as a way of characterizing the ambiguous entity sitting between normal aging and early dementia, corresponding to a GDS of 3 (Table 1) and a CDR of 0.5.[9,10] Our current understanding of MCI as a diagnostic category comes from work by Petersen et al who divorced its diagnosis from other rating scales and proposed diagnostic criteria.[11]

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