[Review and update of the criteria for objective cognitive impairment and its involvement in mild cognitive impairment and dementia].

Introduction: The increase in the incidence and prevalence of dementia has changed the research focus towards its early identification. Several constructs have been developed in order to identify individuals with a high risk of developing dementia, with Mild Cognitive Impairment (MCI) being the term most commonly used in the last decades. However, diagnostic criteria for objective cognitive impairment have been modified using different methods and algorithms.

Aim: This paper aims to provide a review and update of diagnostic criteria for objective cognitive impairment to identify MCI.

Development: ProQuest, OVID SP, ScienceDirect and PSICODOC databases were used to find literature published since 1999 focused on diagnostic criteria for objective cognitive impairment applied to MCI. Papers written in Spanish or English were included.

Conclusions: From an initial search of 1954 articles, 17 were eventually reviewed. The original diagnostic criteria required low scores in one neuropsychological task, biasing MCI towards the amnesic type. Subsequent criteria expanded the number of tests in the battery, which allowed classifying MCI into amnesic and non-amnesic type, as well as into 'single-' and 'multiple' subtypes. Since increasing number of tests affected the probability of diagnostic errors, subsequent criteria incorporated normal variability for the identification of objective cognitive impairment. This work offers a critical review of the strengths and weaknesses of different diagnostic criteria for objective cognitive impairment, for use in both clinical and research settings on MCI and dementia.