Description
Using the original version of the California Verbal Learning Test (CVLT), previous literature found that individuals with Huntington’s disease (HD) show significant deficits compared to those with Parkinson’s disease (PD) on verbal memory indices including total immediate recall, short delay free/cued recall, long delay cued recall, and perseverative errors. However, the groups did not differ on immediate recall span, long delay free recall, semantic/serial clustering, recognition memory, and intrusion errors. No studies have compared verbal memory abilities in individuals with HD or PD using the second edition of the CVLT (CVLT-II). The present study used archival data collected from individuals with PD (n = 72) or HD (n =77). All individuals completed the CVLT-II. Analysis of covariance tests, controlling for education level and Dementia Rating Scale-2 scores, were used to compare HD and PD individuals on standard CVLT-II indices: trial 1 immediate recall, total immediate recall, short delay free/cued recall, long delay free/cued recall, total recognition discriminability, serial/semantic clustering, total intrusion errors, and total repetition errors. Standardized scores, corrected for age and gender, were used as the dependent variables. Cohen’s d effect size estimates also were calculated. The HD group performed significantly worse than the PD group on total immediate recall, short and long-delay free-recall, longdelay cued-recall (ps < .01), and total recognition discriminability (p < .05). All group differences were associated with a large effect size (Cohen’s d). However, trial 1 immediate recall ( p = .13) and semantic clustering (p = .80) did not differ between the groups. The HD group committed more repetition errors (p < .01) than the PD group and the group difference for intrusion error approached significance (p = .06) but was associated with a small effect size (d = .27). The HD group demonstrated poorer serial clustering (p < .01) relative to the PD group, but semantic clustering did not differ between the groups. Our findings are largely consistent with a previous study using the original CVLT in smaller samples. Notable differences include our finding that individuals with HD perform worse than those with PD on long delay free recall and recognition discriminability.
