Neuropsychological subgroups of cognitively-impaired-not-demented (CIND) individuals: delineation, reliability, and predictive validity.

The objectives of the present investigation were to determine whether subgroups of Cognitively-Impaired-Not-Demented (CIND) individuals with distinct neuropsychological profiles exist in two independent samples, and whether subgroup membership is related to diagnostic outcome over periods of 2 to 5 years. A series of cluster analyses was performed on ipsative factor z-scores derived from principal component analyses. Five subgroups were identified in the Base Sample (n = 461): Verbal Dysfunction, Verbal/Visuospatial Dysfunction, Memory/Verbal Dysfunction, Memory Dysfunction, and Visuospatial Dysfunction. This five-cluster solution was replicated in an independent sample of CIND individuals (n = 166). The highest rates of conversion to dementia were observed in the Memory Dysfunction and Memory/Verbal Dysfunction subgroups. The Verbal Dysfunction subgroup was most likely to show improvement in cognitive status. The cognitive heterogeneity of the CIND condition must be taken into account in future research focusing on the early identification of dementia.