Extending MCI beyond Alzheimer disease

Abstract

Mild cognitive impairment (MCI) has emerged as an incipient stage of disease that defines the transition between normal aging and pathologic decline, with an elevated risk of progression to dementia. Despite consensus conferences to develop criteria for MCI, several limitations result in irregular application of these criteria and variability in outcomes. Rates of progression to dementia differ due to variations in population selection, follow-up interval, and operationalization of criteria. For example, diagnoses are generally highest in clinic-based samples (e.g., 15% per year) when compared to community samples (7.3% per year).1 An additional limitation to the concept of MCI is that it has been largely applied to Alzheimer disease (AD), neglecting the multiple other dementing conditions that can evolve from this early state of decline. One study demonstrated that more than 20% of patients with MCI with primary memory impairment progressed to non-AD such as dementia with Lewy bodies, frontotemporal dementia, progressive supranuclear palsy, and vascular dementia.2 Progression of nonamnestic MCI is likely …