Source recognition discriminability impairment in Huntington's versus Alzheimer's disease: Evidence from the CVLT-3

Research suggests that individuals with Huntington's disease (HD) perform better than individuals with Alzheimer's disease (AD) on the California Verbal Learning Test (CVLT) Yes/No Recognition trial. However, those with HD have been shown to have deficits comparable to those with AD on the Source Recognition Discriminability (RD) index (which assesses the ability to distinguish between List A targets and List B distractors), suggesting that HD may involve selective impairment in aspects of yes/no recognition that rely on source memory. However, whether individuals with HD and AD show comparable deficits on Source RD across stages of dementia severity has not been adequately investigated. We examined performance on the CVLT-3 List A vs. List B RD index in individuals with HD or AD and mild or moderate dementia. Among individuals with mild dementia, scores were higher in the HD versus AD group, whereas among individuals with moderate dementia, scores were comparable between the HD and AD groups; this corresponded to differential performance across dementia stages among individuals with HD, but not AD. The present findings suggest that, relative to AD, HD may be associated with disproportionate decline in aspects of yes/no recognition that rely on source memory.