Mild cognitive impairment

Abstract

Purpose of review: The term mild cognitive impairment (MCI) is used to describe older subjects with demonstrable cognitive impairment who have not crossed the threshold for dementia. Because patients with MCI have an increased risk of developing dementia, especially Alzheimer disease (AD), there is significant interest in the clinical characterization of these subjects and in understanding the pathophysiology of the transition from MCI to AD.

Recent findings: The MCI syndrome, as an expression of an incipient disorder that may lead to dementia, is extremely heterogeneous and may coexist with systemic, neurologic, or psychiatric disorders that can cause cognitive deficits. Recent clinical criteria were designed to take into account the different forms of clinical presentation of the syndrome, and introduced the possible contribution of biomarkers to the clinical diagnosis. Bedside diagnosis of MCI can be difficult, since patients who report having cognitive problems may have normal scores in global cognitive scales or in brief neuropsychological instruments.

Summary: This article presents the evolution of the clinical concept of MCI, the operationalization of its current definitions, the development of biomarkers that can help to identify an underlying neurodegenerative process as the etiology of the syndrome, and its proposed treatments.

Figure 7-1

Prevalence of mild cognitive impairment (MCI) in the Pittsburgh Cardiovascular Health Study according to the presence of comorbid conditions. Probable MCI is indicated when the etiology of the MCI syndrome was most likely associated with a neurodegenerative process. Possible MCI is indicated when the etiology of the MCI syndrome could be secondary to medical (eg, cancer), psychiatric (eg, depression), or neurologic (eg, stroke) processes. Reprinted with permission from Lopez OL, et al, Arch Neurol. © 2003, American Medical Association. All rights reserved. archneur.jamanetwork.com/article.aspx?articleid=784823.