Description
In an effort to elucidate early memory profiles associated with Alzheimer’s disease (AD) and Huntington’s disease (HD) pathology, the present study explored the performance of individuals with amnestic mild cognitive impairment (aMCI) or premanifest Huntington’s disease (PreHD) on the California Verbal Learning Test-Second Edition (CVLT-II). While differential profiles of memory performance between individuals with AD and HD are widely supported by a growing body of literature, considerably less is known about the nature of memory changes during prodromal stages of each disease. Previous research has suggested that individuals with PreHD may exhibit memory impairment when compared to demographically similar individuals, though the degree to which the memory profiles associated with PreHD and aMCI differ has not been investigated. Archival data was used in the present study. 18 individuals diagnosed with aMCI and 48 premanifest gene carriers for HD were administered the CVLT-II using standard procedures. Standardized scores corrected for age and gender were used as the dependent variables in all analyses. Nonparametric ANCOVAs using a rank transformation procedure were performed on each of the 14 CVLT-II indices of interest, with participant group (aMCI or PreHD) as the independent variable and education included as a covariate. To correct for multiple comparisons, adjustments for a false discovery rate (FDR) of .05 were applied to the original p values generated from the analyses. Overall, we found that the performance pattern of individuals with aMCI resembled the performance expected of individuals with AD, albeit to a lesser, more subtle degree of impairment. Individuals with PreHD, on the other hand, did not display as many impairments characteristic of individuals with HD, suggesting that less memory deficits may emerge during this premanifest stage of the disease process. Effect sizes were moderate to large (d > .55) for all significant group differences. These findings work to better characterize early cognitive changes associated with AD and HD, and the use of the CVLT-II provides a standardized neuropsychological assessment tool that is both widely accessible and sensitive to early markers of neurodegenerative disease.
