Aims This study investigated verbal learning and memory abilities in manifest Huntington’s disease using the Hopkins Verbal learning Task to determine how and why performance may change over time.
Methods Over a five year follow-up period, standard immediate and delayed memory measures as well as learning curves, serial positions curves and clustering scores were examined annually in a group of twenty mild to moderate Huntington’s disease patients.
Results Free recall, both immediate and delayed, deteriorated significantly over five years, and compared to normative data impaired semantic clustering, learning curve trajectory and serial position effects were evident from the baseline assessment. While recognition performance appeared relatively intact over time, the significant increase of false positive errors suggested that this was achieved in parallel with an over-inclusive recognition response bias.
Conclusion The patterns of longitudinal decline and deviations from normative data reported in the literature implicate continuing impairment of executive function processes in mild to moderate HD. Our data underlines the very gradual nature of verbal memory impairment which suggests that these measures are less suitable for shorter studies, although they remain useful indicators of day to day memory.
- verbal memory