Abstract-Objective:To empirically validate the expanded concept of mild cognitive impairment (MCI), which differentiates between four clinical subtypes-amnestic MCI-single domain, amnestic MCI-multiple domains, nonamnestic MCIsingle domain, and nonamnestic MCI-multiple domains-and to examine the prevalence, course, and outcome of these four clinical MCI subtypes. Methods: We studied a community sample of 980 dementia-free individuals aged 75 years or older who participated in the Leipzig Longitudinal Study of the Aged (LEILA 75ϩ). All participants were examined by neuropsychological testing based on 6 years of observation. The diagnoses of the four clinical MCI subtypes were made according to the original and to slightly modified criteria by Petersen et al. (2001) (both with a cutoff of 1.0 SD and with a cutoff of 1.5 SD). The complete range of outcome types (dementia, death, improvement, stable diagnosis, unstable diagnosis) was described for all subtypes. The relative predictive power of stable MCI for dementia onset was determined. Results: MCI-single domain is more frequent than MCI-multiple domains, and the nonamnestic MCI type is as frequent as the amnestic MCI type. The "MCI modified, 1.0 SD" criteria have the highest relative predictive power for the development of dementia (sensitivity ϭ 74%, specificity ϭ 73%). Alzheimer disease (AD) was the most common type of dementia at follow-up in all but one MCI subtype. Participants with nonamnestic MCI-multiple domains were more likely to progress to a non-AD dementia. Conclusions: It has been assumed that each MCI subtype is associated with an increased risk for a particular type of dementia. We can only partially agree with this. NEUROLOGY 2006;67:2176-2185 The expanded concept of mild cognitive impairment (MCI) distinguishes four clinical subtypes: amnestic MCI-single domain, amnestic MCI-multiple domains, nonamnestic MCI-single domain, and nonamnestic MCI-multiple domains.
1,2These four clinical subtypes assumedly differ in etiology and outcome.1,2 Amnestic MCI (single domain as well as multiple domains) is said to have a high likelihood of progressing to Alzheimer disease (AD) dementia. The nonamnestic subtypes are assumed to have a higher likelihood of progressing to a non-AD dementia.
1,2This study addresses several questions. What is the prevalence of the subtypes of MCI? Which types of dementia do the subtypes of MCI commonly relate to? In this study, we also examine the course of and 6-year outcome of MCI in a representative general population sample aged 75 years and older, and describe the complete range of outcome types (dementia, death, improvement, stable diagnosis, unstable diagnosis).Method. Sample. The data were derived from the Leipzig Longitudinal Study of the Aged (LEILA 75ϩ), a population-based study of the epidemiology of dementia and MCI.3 All subjects gave written informed consent to participate in this study. The local ethics committee approved this study. The total LEILA 75ϩ sample was comprised of a total of 1,692 community-dwelling ...