ABSTRACT
Regarding cognitive heterogeneity, despite the dominant focus on individuals with relatively isolated memory impairment, a consensus is emerging that MCI also encompasses individuals with impairment in cognitive domains other than memory. Petersen et al. (2001) have described three subgroups2 of MCI: MCI-amnestic, MCI-multiple domain, and MCI-single nonmemory domain. These authors also suggest that the different MCI subgroups might be at increased risk for progressing to different types of dementia. For example, while an individual in the amnestic subgroup may develop AD, an individual in the single nonmemory domain subgroup is more likely to progress to another form of dementia (e.g., frontotemporal dementia or Lewy body dementia). Using a combination of factor and cluster analyses, Peters, Graf, Hayden, and Feldman (2005) identified five subgroups of cognitively impaired-not demented (CIND) individuals in two independent samples. Each subgroup was characterized by a distinct profile of cognitive abilities, and included: Verbal Dysfunction, Memory Dysfunction, Visuospatial Dysfunction, Memory/Verbal Dysfunction, and Verbal/Visuospatial Dysfunction. The results reported by Peters and colleagues provide empirical validation of the MCI subgroups proposed by Petersen etal. (2001).
