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. Author manuscript; available in PMC: 2025 Nov 1.
Published in final edited form as: Appl Neuropsychol Adult. 2022 Aug 19;31(6):1163–1168. doi: 10.1080/23279095.2022.2112682

Source Recognition Discriminability Impairment in Huntington’s versus Alzheimer’s Disease: Evidence from the CVLT-3

Lisa V Graves a, Emma G Churchill b, McKenna E Williams c, Emily J Van Etten d, Mark W Bondi e,f, David P Salmon g, Jody Corey-Bloom g, Dean C Delis f, Paul E Gilbert b,c
PMCID: PMC9938836  NIHMSID: NIHMS1853485  PMID: 35984776

Abstract

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.

Keywords: Huntington’s disease, Alzheimer’s disease, memory deficits, memory disorder, recognition, California Verbal Learning Test

Huntington’s disease (HD) and Alzheimer’s disease (AD) involve distinct neuropathological processes that yield different patterns of memory loss (Butters et al., 1986; Delis et al., 1991; Salmon & Filoteo, 2007). Due to neurodegeneration that heavily targets the medial temporal lobes and cortical association areas, AD is associated with an encoding/storage deficit profile characterized by poor learning, rapid forgetting over time, and impaired recognition performance (Butters et al., 1986; Delis et al., 1991; Moss et al., 1986). In contrast, due to neuropathology that primarily targets subcortical-frontal networks, individuals with HD often exhibit a retrieval deficit profile characterized by impaired recall with improved or less compromised performance on recognition testing (Massman et al., 1992).

Source memory involves the ability to recall the context from which information was learned or acquired. An example of a real-world source memory difficulty would be an individual recalling the purpose of a medication they are taking, but forgetting whether they learned that information from their physician or from their partner. Multiple studies have suggested that the frontal lobes, in particular, are strongly implicated in source memory (Baldo et al., 2002; Craik et al., 1990; Duarte et al., 2005; Janowsky et al., 1989). Moreover, research has shown that individuals with HD and other groups with frontal system dysfunction show difficulty recalling whether they had learned specific information (a) during an earlier portion of the same test, or, (b) prior to administration of that test, suggesting a tendency to confuse the source of newly learned or acquired information (Brandt et al., 1995). Multiple studies also have yielded evidence for similar source memory difficulties in AD (Dalla Barba et al., 1999; Fowler et al., 2002). However, whereas HD may involve a selective impairment on the source memory aspects of recognition testing with increasing subcortical-frontal system involvement over the course of the disease, the source memory difficulties in AD are likely to reflect a global and profound decline in all aspects of recognition testing (with recognition deficits observed early in and throughout the disease process) due to their pervasive encoding/storage impairment resulting from medial temporal lobe involvement.

The CVLT-II (Delis et al., 2000) included a Source Recognition Discriminability (RD) index that assessed the ability to distinguish between List A targets and List B distractor items (i.e., words previously presented during test administration, on the List B interference list) during the Yes/No Recognition trial. A higher index score indicates better source recognition. Research has shown that, on the CVLT-II, individuals with HD perform similarly to individuals with AD on the Source RD index despite performing better than those with AD on the Yes/No Recognition trial overall (i.e., having higher Total RD scores; Fine et al., 2008; Graves et al., 2017). HD and AD differences on total recognition have also been observed more recently on the CVLT-3 (Graves et al., 2018; Graves et al., 2019). Thus, although yes/no recognition is generally less compromised in HD than in AD, HD is likely still associated with selective impairment in aspects of yes/no recognition that rely on source memory due to subcortical-frontal system involvement, resulting in comparable deficits to AD on that particular construct. In these previous studies, HD and AD patient groups generally included individuals with dementia ranging from mild to moderate in severity. However, none of these studies classified HD and AD patients into separate mild and moderate dementia subgroups to facilitate an analysis of whether individuals with HD and AD show similar degrees of Source RD impairment within and across these distinct stages of dementia severity (a missed opportunity in hindsight).

In the present study, we examined performance on the CVLT-3 (Delis et al., 2017) List A vs. List B RD index (formerly the CVLT-II Source RD index) in individuals with HD or AD who have mild or moderate dementia. We hypothesized that among individuals with HD, those with mild dementia would have higher List A vs. List B RD index scores (indicative of better source recognition) than those with moderate dementia, given that progressing subcortical-frontal system involvement in HD likely results in disproportionate decline in aspects of yes/no recognition that rely on source memory. In contrast, we did not expect List A vs. List B RD performance to vary as a function of dementia severity in individuals with AD, given the global and profound decline in all aspects of recognition memory performance associated with AD. Accordingly, we hypothesized that List A vs. List B RD index scores would be higher in HD than in AD among individuals with mild dementia, but comparable across the two disorders among individuals with moderate dementia.

Materials and Methods

Participants

Study participants included 55 individuals with HD and 52 individuals with AD, who were each characterized as mild or moderate on dementia severity based on Dementia Rating Scale (DRS; Mattis, 1988) or DRS-2 (Jurica et al., 2001) scores: 120 or above = mild, 100–119 = moderate (mod). Accordingly, the study sample consisted of four groups, including 39 Huntington’s disease-mild (HD-mild), 16 Huntington’s disease-moderate (HD-mod), 25 Alzheimer’s disease-mild (AD-mild), and 27 Alzheimer’s disease-moderate (AD-mod) participants (note: the sample in the present study overlaps to varying degrees with those in previous studies conducted by Graves and colleagues but is the first to directly examine HD and AD performance on the CVLT-3 List A vs. List B RD index [see below]). Individuals with HD were recruited from the Huntington’s Disease Clinical Research Center (HDCRC) at the University of California, San Diego (UCSD) and were administered the Unified Huntington’s Disease Rating Scale (UHDRS; Huntington Study Group, 1996) by a senior staff neurologist. Individuals with HD were diagnosed with definite HD on the basis of unequivocal motor signs on the UHDRS and a positive family history of HD. In addition, all HD participants had a CAG repeat length greater than 39, indicating that all carried the fully penetrant genetic mutation for HD. Individuals with AD were recruited from the UCSD Shiley-Marcos Alzheimer’s Disease Research Center (ADRC). Diagnoses of individuals with probable AD were made by a senior staff neurologist at the ADRC and were consistent with the criteria established by the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association (NINCDS-ADRDA) and the National Institute on Aging–Alzheimer’s Association (NIA-AA) workgroups (McKhann et al., 1984; McKhann et al., 2011). Exclusionary criteria for HD and AD participants included the following: diagnosis of a neurological disorder aside from HD or AD, respectively; diagnosis of a major medical condition (e.g., cancer); history of traumatic brain injury; diagnosis of a major psychiatric disorder (with the exception of a mood or anxiety disorder for which current symptoms must have been well-managed with medication and/or psychotherapy); and history of a substance use disorder. All participants provided informed written consent and the study was approved by the Institutional Review Board of UCSD. The study was conducted in accord with the Helsinki Declaration of 1975.

Participant data examined in the present study were originally collected during annual visits with the UCSD HDCRC or ADRC. However, the dataset that was provided to our group and used for the present analysis included only a subset of demographic, clinical, and neuropsychological variables collected from these visits. Of note, participant race/ethnicity data were not available in this dataset and thus could not be reported in the present analysis.

CVLT-3 Variables of Interest

The CVLT-II is a list-learning test that provides several verbal learning and memory indices, including learning, free and cued recall over short and long delays, and Yes/No Recognition. The CVLT-II was administered as part of a comprehensive test battery using standard procedures outlined by Delis and colleagues (2000). Given that the CVLT-II and CVLT-3 contain identical target words on the recall trials and identical targets and distractors on the Yes/No Recognition trial, CVLT-3 algorithms and norms (Delis et al., 2017) were applied to CVLT-II data to generate age-corrected scaled scores on CVLT-3 indices. Raw CVLT data were obtained retrospectively from existing patient registries associated with the parent UCSD HDCRC and ADRC studies, and scaled scores on CVLT-3 variables were derived manually and prospectively using available raw scores in the available dataset and norms tables in the CVLT-3 manual (Delis et al., 2017). Scaled scores on the CVLT-3 adjust for age (on the CVLT-II, scaled scores adjust for both age and sex).

The List A vs. List B RD index (assesses the ability to distinguish between List A targets and List B distractor items) was the variable of primary interest. Scaled scores on Trial 5 (the final immediate recall trial), List B (recall of a distractor list), Long Delay Free Recall (of List A), and Total RD (assesses the ability to distinguish between List A targets and all distractor items) were also examined; these additional variables were selected on the basis of their relevance (i.e., as key/core indices assessing recall of Lists A and B as well as recognition) and the availability of raw scores in the available dataset as well as corresponding norms tables in the CVLT-3 manual to generate scaled scores for analysis. While RD scores (total, List A vs. List B) were available on all study participants, subsets of participants had missing scores on the other CVLT-3 variables examined in the present study. Additionally, raw and process scores were not available on other CVLT indices of source memory (e.g., across-trial intrusions), thus, these were omitted from the present analysis.

Statistical Analyses

Analyses were conducted in the Statistical Package for the Social Sciences (SPSS) Version 28.

Demographic and preliminary analyses.

One-way analysis of variance (ANOVA) (with Tukey’s post-hoc pairwise comparisons) and chi-square tests were conducted to examine group differences on demographic variables, including age (years), sex/gender (male or female), and education (years), as well as DRS/DRS-2 scores. Additionally, preliminary ANOVA and ANCOVA tests were conducted to determine whether any demographic variables were significant predictors of List A vs. List B RD performance.

Primary analyses.

An ANOVA test was conducted to examine the effect of group (HD-mild, HD-mod, AD-mild, AD-mod) on scaled scores on the List A vs. List B RD index. ANOVA tests were also conducted to examine the effect of group on scaled scores on Trial 5, List B, Long Delay Free Recall, and the Total RD index, to supplement the analysis of the List A vs. List B RD index, the primary variable of interest. Post-hoc pairwise comparisons were conducted to examine group differences in the context of significant group effects. The following comparisons were of interest and are emphasized in the discussion of results and their implications: (1) HD-mild vs. HD-mod, (2) AD-mild vs. AD-mod, (3) HD-mild vs. AD-mild, and (4) HD-mod vs. AD-mod. A Bonferroni adjustment was applied to correct for multiple comparisons: αBC = .05/4 = .013.

Tests of assumptions.

Assumptions of ANOVA/ANCOVA and chi-square were tested. With regard to ANOVA, dependent and independent variables were on appropriate scales of measurement (continuous and categorical, respectively). There were no violations of independence. The List B scaled score distribution was platykurtic in the AD-mild group, and LDFR scaled score distributions were both right-skewed and leptokurtic in the AD-mild and AD-mod groups, yet platykurtic in the HD-mod group. Additionally, Shapiro-Wilk tests were significant for LDFR in the AD-mild and AD-mod groups (ps < .05). There was no evidence of skewness or kurtosis on the primary variable of interest, List A vs. List B RD. Homogeneity of variances was observed for scaled scores on List A vs. List B RD and most secondary CVLT-3 variables of interest (with the exception of List B, for which Levene’s test statistics had corresponding ps < .05). However, Levene’s test was significant (ps < .05) for raw scores on List A vs. List B RD, with HD groups showing greater variance relative to the AD groups. Homogeneity of regression slopes was observed for raw scores on List A vs. List B RD in the preliminary ANCOVA test. All chi-square assumptions were met. No scores on CVLT-3 variables were observed to fall outside the possible or expected range of measurement.

Results

Demographic Analyses

Demographic information on study participants is provided in Table 1. One-way ANOVA tests revealed a significant association of group with age, F(3, 103) = 80.89, p < .001, η2p = .70, and DRS/DRS-2 scores, F(3, 103) = 84.86, p < .001, η2p = .71, but not education, F(3, 103) = 1.62, p = .19, η2p = .05. Tukey’s post-hoc pairwise comparisons showed that the HD-mild and HD-mod groups were significantly younger than the AD-mild and AD-mod groups (ps < .001), which is to be expected given differences in typical age of onset associated with the two disorders. However, there were no differences in age between the HD-mild and HD-mod groups, or between the AD-mild and AD-mod groups (ps > .05). Additionally, Tukey’s post-hoc pairwise comparisons showed that the HD-mild and AD-mild groups had significantly higher DRS/DRS-2 scores than the HD-mod and AD-mod groups (ps < .001), as expected. However, there were no differences in DRS/DRS-2 scores between the HD-mild and AD-mild groups, or between the HD-mod and AD-mod groups (ps > .05). A chi-square test revealed a significant difference in sex/gender distributions across groups, χ2 (3, N = 107) = 8.58, p = .04, Cramer’s V = .28. Post-hoc tests showed a higher proportion of women than men in the HD-mild group; comparable proportions of men and women in the HD-mod and AD-mild groups; and a higher proportion of men than women in the AD-mod group (ps < .05).

Table 1.

Mean (standard deviation) and percentage values on demographic variables in the Huntington’s disease-mild (HD-mild), Huntington’s disease-moderate (HD-mod), Alzheimer’s disease-mild (AD-mild), and Alzheimer’s disease-moderate (AD-mod) groups.

Demographic Variable HD-mild (n=39) HD-mod (n=16) AD-mild (n=25) AD-mod (n=27)
Age 49.62 (11.55) 50.00 (12.22) 75.28 (4.84) 78.67 (5.02)
% Female 66.67 56.25 40.00 33.33
Education 14.15 (2.32) 14.19 (2.29) 15.44 (2.89) 15.22 (3.39)
DRS/DRS-2 Total Score 129.36 (5.29) 113.31 (6.72) 126.88 (3.79) 112.70 (4.11)
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Preliminary Analyses

ANCOVA tests revealed that age, F(1, 105) = 21.85, p < .001, η2p = .17, and DRS/DRS-2 scores, F(1, 105) = 30.67, p < .001, η2p = .23, were significant predictors of raw scores on the List A vs. List B RD index. However, given that CVLT-3 scaled scores correct for age, age was not included as a covariate in primary analyses examining scaled scores on the List A vs. List B RD index. Moreover, given that DRS/DRS-2 scores were systematically varied by group (i.e., individuals with HD or AD were characterized as mild or moderate on dementia severity), DRS/DRS-2 scores were not controlled for in primary analyses examining scaled scores on the List A vs. List B RD index. Importantly, sex/gender and education were not shown to be significant predictors of List A vs. List B RD performance (ps > .05).

Primary Analyses: HD and AD Performance on List A vs. List B RD

Scaled scores on CVLT-3 variables are provided in Table 2. An ANOVA test revealed a significant association of group with scaled scores on the List A vs. List B RD index, F(3, 103) = 4.87, p < .01, η2p = .12. Bonferroni-adjusted post-hoc pairwise comparisons revealed that List A vs. List B RD index scores were significantly higher in the HD-mild group than in all other HD and AD groups (ps < .01). That is, performance was significantly better in the HD-mild group than in the HD-mod group (p < .01; d =.74), whereas the AD-mild group and AD-mod group exhibited comparable performance (p > .05). Thus, significant differences as a function of dementia severity were observed among individuals with HD, but not among those with AD. Additionally, performance was significantly better in the HD-mild group than in the AD-mild group (p < .01; d = .69), whereas the HD-mod group and AD-mod group exhibited comparable performance (p > .05). Thus, significant HD and AD differences were observed among individuals with mild dementia, but not among those with moderate dementia. Group differences on scaled scores on the List A vs. List B RD index are illustrated in Figure 1.

Table 2.

Mean (standard deviation) scaled scores on CVLT-3 variables in the Huntington’s disease-mild (HD-mild), Huntington’s disease-moderate (HD-mod), Alzheimer’s disease-mild (AD-mild), and Alzheimer’s disease-moderate (AD-mod) groups.

CVLT-3 Variable HD-mild HD-mod AD-mild AD-mod
Trial 5 6.09 (3.01)
n=35		 3.67 (2.26)
n=15		 6.29 (1.78)
n=24		 4.93 (1.88)
n=27
List B 7.77 (2.91)
n=35		 5.47 (1.89)
n=15		 8.40 (1.84)
n=10		 7.85 (1.63)
n=13
Long Delay Free Recall 5.77 (2.56)
n=35		 3.80 (1.82)
n=15		 3.71 (2.31)
n=24		 3.00 (1.27)
n=27
Total RD 5.77 (2.59)
n=39		 4.38 (2.06)
n=16		 4.52 (2.20)
n=25		 4.11 (2.21)
n=27
List A vs. List B RD 6.31 (2.75)
n=39		 4.44 (2.25)
n=16		 4.64 (2.02)
n=25		 4.41 (2.10)
n=27
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Note: RD = recognition discriminability.

Figure 1.

Figure 1.

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Mean (standard error) scaled scores on the List A vs. List B RD index in the Huntington’s disease-mild (HD-mild), Huntington’s disease-moderate (HD-mod), Alzheimer’s disease-mild (AD-mild), and Alzheimer’s disease-moderate (AD-mod) groups.

ANOVA tests also revealed a significant association of group with scaled scores on: Trial 5, F(3, 97) = 5.12, p < .01, η2p = .14; List B, F(3, 69) = 4.23, p < .01, η2p = .16; Long Delay Free recall, F(3, 97) = 9.94, p < .001, η2p = .24; and the Total RD index, F(3, 103) = 3.30, p < .05, η2p = .09. Bonferroni-adjusted post-hoc pairwise comparisons revealed that Trial 5 scores were significantly lower in the HD-mod group than in the HD-mild group (p < .005; d = 0.75). List B scores were significantly lower in the HD-mod group than in all other groups (ps < .013; ds = 0.87 to 1.57). Long Delay Free Recall scores were significantly higher in the HD-mild group than in all other groups (ps < .005; ds = 0.83 to 1.32). Total RD scores were significantly higher in the HD-mild group than in the AD-mod group (p < .01; d = 0.68), although this was not a primary comparison of interest, and no other group differences on the total RD index were observed (after Bonferroni corrections). Of note, exploratory post-hoc hierarchical logistic regressions (with Total RD entered in Step 1 and List A vs. List B RD entered in Step 2) provided evidence for the incremental utility of List A vs. List B RD over Total RD in distinguishing between HD and AD patients with mild (but not moderate) dementia (for the logistic regression model including the HD-mild and AD-mild groups: χ2 [2, N = 64] = 8.11, p < .05]; for the logistic regression model including the HD-mod and AD-mod groups, χ2 [2, N = 43] = 1.10, p > .05).

Discussion

In the present study, we examined performance on the CVLT-3 List A vs. List B RD index (formerly the CVLT-II Source RD index) in individuals with HD or AD who have mild or moderate dementia. Findings indicated that among individuals with HD, List A vs. List B RD index scores were higher in those with mild dementia than in those with moderate dementia. In contrast, among individuals with AD, performance did not vary as a function of dementia severity. Thus, greater dementia severity was associated with worse source recognition in individuals with HD, but not in those with AD. Moreover, among individuals with mild dementia, List A vs. List B RD index scores were higher in the HD group than in the AD group, whereas among individuals with moderate dementia, performance was comparable between the HD and AD groups. Thus, HD and AD differences in source recognition were observed in the context of mild, but not moderate, dementia severity. Furthermore, List A vs. List B RD (source recognition) was shown to have incremental utility over Total RD (total recognition) in distinguishing between HD versus AD among those with mild (but not moderate) dementia, bolstering evidence from primary analyses of the utility of the List A vs. List B RD index and assessing source memory in differentiating mild dementia due to HD versus AD.

Results supported our hypothesis that greater dementia severity in individuals with HD would be associated with a disproportionate decline in List A vs. List B performance due to the disproportionate impact of progressing subcortical-frontal system pathology and dysfunction on aspects of yes/no recognition that rely on source memory. Additionally, results supported our hypothesis that for individuals with AD, all aspects of yes/no recognition memory are severely impaired early in the disease process due to their pervasive encoding/storage deficit resulting from medial temporal lobe involvement, and thus, these individuals would not exhibit differential List A vs. List B RD performance across stages of dementia severity.

The observed patterns of HD and AD performance on source recognition within and across mild and moderate stages of dementia severity were not mirrored on total recognition, suggesting that, relative to AD, HD may be associated with disproportionate decline in aspects of yes/no recognition that rely on source memory in particular. HD patients with mild dementia did demonstrate better total recognition compared to AD patients with moderate dementia, but this was not a comparison of primary interest, and no other significant group differences on total recognition were observed. Analyses of other CVLT-3 indices revealed the following: (1) immediate recall (as measured by performance on Trial 5, the final immediate recall trial) worsened with increasing dementia severity for HD patients, but was consistently impaired across stages of dementia severity for AD patients (consistent with robust evidence in the literature for profound recall deficits in AD due to medial temporal lobe involvement); (2) HD patients with moderate dementia were more vulnerable to proactive interference (performed worse on List B recall) compared to all other groups in the study sample (which could reflect a consequence of progressing subcortical-frontal system involvement in HD; Massman et al., 1990); and (3) HD patients with mild dementia showed better delayed recall (as measured by performance on the Long Delay Free Recall trial) compared to all other groups in the sample (also consistent with evidence for profound recall deficits in AD, but not HD, due to medial temporal involvement). These findings highlight that in addition to profound recall deficits in AD, a notable distinction in the memory profiles of HD and AD is the disproportionate decline across mild and moderate stages of dementia, among individuals with HD, in aspects of yes/no recognition that rely on source memory, likely due to progressing subcortical-frontal system pathology and dysfunction. Thus, a major clinical implication of our study findings is that the List A vs. List B RD index on the CVLT-3 offers utility in tracking the course of decline in HD, such that source recognition is more likely to progressively worsen in HD patients as they transition through stages of greater dementia severity.

The present study is not free of limitations. First, our findings are likely underpowered given the small size of our study sample, and of HD patients with moderate dementia in particular. Specifically, for the omnibus effect of group on List A vs. List B RD scaled scores, power analysis indicated an achieved power of 0.15. However, regarding the specific group comparisons on List A vs. List B RD that corresponded to our study hypotheses, power analysis indicated an achieved power of .76 for the HD-mild versus HD-mod comparison and .82 for the HD-mild versus AD-mild comparison. Second, participants recruited by the UCSD HDCRC and ADRC are generally highly educated and non-Hispanic White. Moreover, as we noted previously, participant race/ethnicity data were not provided in the available dataset and thus could not be reported in the present analysis. Taken together, these issues further limit the generalizability of our study findings. Third, the present study utilized a cross-sectional design, which inherently poses limits on the extent to which findings may be used to draw inferences regarding the longitudinal trajectories of (i.e., declines in) List A vs. List B RD performance in HD versus AD. Fourth, one of the study exclusion criteria was diagnosis of a major psychiatric disorder, with the exception of a mood or anxiety disorder for which current symptoms must have been well-managed with medication and/or psychotherapy. While data regarding the prevalence of mood disorders and treatment in the present study sample were not available, it is worth noting that depression is common among HD patients, and that psychotropic medications in particular can affect memory functioning. Finally, the present findings would be strengthened by the analysis of additional source memory and everyday functioning measures. For example, Babicz et al. (2020) have reported evidence for the construct and criterion validity of across-list intrusions (i.e., the number of times that an examinee erroneously generates a word from List A during the List B trial, or, from List B during any of the List A delayed recall trials) in conjunction with source recognition discriminability on the CVLT in assessing source memory impairment. Taken together, future studies with larger, more diverse, and better-characterized study samples leveraging longitudinal designs and incorporating additional source memory and everyday functioning indices are needed to further enhance characterizations and distinctions of the memory disorders associated with HD and AD.

In summary, the present findings bolster prior evidence for disproportionate Source RD impairment in HD (Fine et al., 2008; Graves et al., 2017; Graves et al., 2018; Graves et al., 2019). However, earlier studies did not include an analysis of whether HD and AD performance on the Source RD index varied as a function of dementia severity. Thus, the current results extend prior findings by highlighting that, relative to AD, HD may be associated with disproportionate decline across stages of dementia severity in aspects of yes/no recognition that rely on source memory. In clarifying the possible trajectory of decline in HD versus AD in more nuanced aspects of yes/no recognition that are sensitive to source memory, the present findings promise to improve characterizations of the memory profiles associated with these two disorders, and may in turn elucidate patterns of memory loss in other neurological conditions involving subcortical-frontal versus medial temporal pathology and dysfunction.

Acknowledgements

We sincerely thank our research assistant, Maiya Larry, for her help with generating scaled scores on CVLT-3 variables of interest in the present study.

Funding Details

This work was supported in part by the National Institutes of Health (R01 AG034202 to P.E.G. and R01 AG049810 to M.W.B.), the Shiley-Marcos ADRC (P30 AG062429 to D.P.S.), and the UCSD Huntington’s Disease Society of America (Center of Excellence grant to J.C.B.).

Footnotes

Disclosure of Interest

Dr. Delis is an author of the CVLT and receives royalties for the test. Dr. Bondi receives royalties from Oxford University Press. Dr. Salmon is a consultant for Biogen Inc. and Aptinyx Inc.

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