Neuropsychological Profile and Performance Variability in Vascular Cognitive Impairment

Background: Cognitive impairment from cerebrovascular disease varies in scope. Methods: We studied healthy elderly individuals and those with mild cognitive impairment (MCI) or mild dementia attributed to vascular pathology, in order to assess the diagnostic utility of intra-individual variability across neuropsychological domains and the cognitive profile of vascular cognitive disorders. A large battery of tests was used to create z-scores for seven neuropsychological domains by principle components analysis. Results: We did not find group differences in the average intra-individual variance across neuropsychological domains. We did find group differences in the within-domain variability for Language, reflecting increased performance variability in those participants with vascular pathology. There was a lower inter-correlation of domain scores in the MCI group than in the mild vascular dementia (VD) group. The MCI group had the largest deficits in Executive Function, Fluency and Memory relative to the healthy control (HC) group. The VD group evidenced a broad range of further cognitive decline relative to the MCI group, with the largest difference on Visuoconstruction. Conclusions: While intra-individual performance variability may increase early in the course of cognitive decline from vascular pathology, this is not because of greater across-domain variability or because impairments occur in only one particular cognitive domain or small cluster of inter-related domains. Early cognitive change includes decreased executive function that cannot be attributed to slow information processing or response time.