Is verbal recognition memory really different in Huntington's and Alzheimer's disease.

Verbal recall and recognition were examined in Huntington's disease (HD) and Alzheimer's disease (AD) patients. Subgroups of HD and AD patients were matched for overall severity of dementia. Subjects were administered the Hopkins Verbal Learning Test, a list-learning task with three free-recall trials followed immediately by one yes/no recognition trial with semantically related and unrelated distractors. The matched AD and HD groups did not differ in the number of words recalled, although the HD patients showed slightly greater improvement over trials. Recognition performance was evaluated with measures of accuracy and response bias that are independent of each other. The matched groups did not differ in overall recognition accuracy, but the AD patients tended to have a more liberal ("yea-saying") response bias than did the HD patients. In addition, only the AD patients were differentially enticed to false-positive responding by semantically related distractors. The results suggest that the rule for making decisions when uncertain, rather than memory strength per se, distinguishes the recognition memory performance of AD and HD patients.     

Patterns of verbal memory performance in mild cognitive impairment, Alzheimer disease, and normal aging.

OBJECTIVE: Individuals with mild cognitive impairment (MCI) typically demonstrate memory loss that falls between normal aging (NA) and Alzheimer disease (AD), but little is known about the pattern of memory dysfunction in MCI. METHOD: To explore this issue, California Verbal Learning Test (CVLT) performance was examined across groups of MCI, AD, and NA. RESULTS: MCI subjects displayed a pattern of deficits closely resembling that of AD, characterized by reduced learning, rapid forgetting, increased recency recall, elevated intrusion errors, and poor recognition discriminability with increased false-positives. MCI performance was significantly worse than that of controls and better than that of AD patients across memory indices. Although qualitative analysis of CVLT profiles may be useful in individual cases, discriminant function analysis revealed that delayed recall and total learning were the best aspects of learning/memory on the CVLT in differentiating MCI, AD, and NA. CONCLUSIONS: These findings support the position that amnestic MCI represents an early point of decline on the continuum of AD that is different from normal aging.     

Detection of abnormal memory decline in mild cases of Alzheimer's disease using CERAD neuropsychological measures

The present study was designed to determine which of the memory tasks included in the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) neuropsychological battery best differentiate patients with early Alzheimer's disease from cognitively normal elderly control subjects and also best distinguish between the various levels of severity of the dementia process. A sample of CERAD patients with Alzheimer's disease was stratified by disease severity into those with mild, moderate, or severe dementia and matched with control subjects for sex, age, and education. Using multivariate procedures and cutting scores, the efficacy of each memory measure in distinguishing between these groups and control subjects was determined. The test for delayed recall was found to be the best overall discriminatory measure. The other tests of memory, ie, immediate recall, intrusion errors, and recognition memory, had poor overall discriminability. None of the CERAD memory measures were found to be particularly powerful in staging the severity of dementia. These findings suggest that tests for delayed recall may be particularly useful in the early detection of Alzheimer's disease and should be considered in screening batteries for dementia in community surveys.     

Retrieval-induced forgetting in Alzheimer's disease

It is claimed that Alzheimer's disease (AD) patients show reduced inhibitory processing and this has been put forward as a reason why AD patients make intrusion errors at recall. However, the evidence to date has been equivocal, because non-inhibitory mechanisms can account for the pattern of findings. Recently, however, a paradigm has been developed that is claimed to give a purer measure of inhibitory processing in episodic memory, the retrieval-induced forgetting (RIF) paradigm [Inhibitory Processes in Attention, Memory and Language, Academic Press, San Diego, 1994, p. 265; J. Exp. Psychol.: Learning, Memory Cognition 20 (1994) 1063; Psychol. Rev. 102 (1995) 68]. Thus, we were interested whether AD patients would show a deficit in inhibitory processing using this procedure. Participants studied lists of category cue-exemplar pairs (e.g. fruit-orange) then practised retrieval for a subset of items from a subset of categories before taking a final memory test for all studied items. As in previous work, inhibition was measured as the difference between final memory performance for unpractised items from practised categories, and unpractised items from unpractised categories. The results show that AD patients showed normal levels of inhibition with both tests of cued recall and category generation (CG). This suggests that a deficit in inhibitory processes during retrieval is not behind the high levels of intrusion errors made in recall in AD.     

Identifying the "source" of recognition memory deficits in patients with Huntington's disease or Alzheimer's disease: evidence from the CVLT-II

The present study compared the performance of individuals with Huntington's disease (HD) and Alzheimer's disease (AD) on three types of California Verbal Learning Test-Second Edition (CVLT-II) recognition discriminability indices (RDI): Source, Novel, and Total. The HD and AD groups did not differ significantly on Source RDI (all 16 targets versus the 16 previously presented, List B, distractors). However, HD patients performed significantly better than AD patients on Total RDI (all 16 targets versus all 32 distractors) and Novel RDI (all 16 targets versus 16 new distractors). Implications of these findings on the differentiation of the memory disorders associated with HD and AD are discussed.     

Different error pattern of episodic and semantic memory in Alzheimer's disease and Parkinson's disease with dementia

To evaluate the possible differences in memory dysfunction we analysed the episodic and semantic memory of patients with Alzheimer's disease (AD) and Parkinson's disease (PD) with dementia, and age-matched normal controls (NC). The memory was examined with story recall tests, list learning test with Buschke selective reminding method and category naming test. Both AD and PD groups committed more prior-story intrusion errors as compared with the NC subjects, but only the AD patients committed more extra-story intrusion errors. Both patient groups committed more extra-list intrusion errors than the NC group. Furthermore, the AD patients made more extra-list intrusion errors and recognized more false positive targets than the PD patients did. The results suggest that AD and PD patients have different patterns of memory dysfunction. The AD patients seem to perform poorly because of their inability to inhibit irrelevant information and because of increased sensitivity to interference, whereas the deficits of PD patients only reflect sensitivity to proactive interference.     

An assessment of verbal recall, recognition and fluency abilities in patients with Huntington's disease

Two investigations concerned with the memory deficits of patients with Huntington's Disease (HD) were performed. In the first experiment, early and advanced HD patients showed superior recognition memory than did alcoholic Korsakoff patients on modified recall and recognition forms of the Rey Auditory Verbal Learning Test. In contrast, on a letter fluency test (FAS) requiring the patients to search their semantic memories, both HD groups produced fewer correct words and perseveration errors than did the alcoholic Korsakoff group. In the second experiment, HD patients and Korsakoff patients were compared in their and recognition of short passages. While the HD and Korsakoff patients were equally impaired on recall tests, the HD patients evidenced significantly better recognition memory than did the amnesic group. As on the fluency test, the prose of the Korsakoff patients was characterized by intrusion (i.e., perseverative) errors. The results of the two experiments indicate that HD and Korsakoff patients' memory deficits are related to deficiencies in retrieval and an increased sensitivity to proactive interference, respectively.     

Differences in olfactory and visual memory in patients with pathologically confirmed Alzheimer's disease and the Lewy body variant of Alzheimer's disease.

Recognition and remote memory for odors, faces, and symbols were assessed in patients with pathologically confirmed Lewy body variant of Alzheimer's disease (LBV), patients with pathologically confirmed Alzheimer's disease (AD), and healthy elderly controls. On recognition memory tasks, LBV and AD patients showed significantly lower discriminability (d') than controls, particularly for olfactory stimuli. However no significant differences were found in the bias measure (c). When participants rated familiarity (a proposed measure of remote memory) of olfactory stimuli LBV and AD patients reported significantly lower familiarity than controls. Familiarity ratings were significantly lower in LBV patients than in AD patients for olfactory, but not for visual stimuli. Consistent with prior reports, the LBV patients showed significantly poorer odor thresholds than AD patients. The results suggest that recognition memory for olfactory stimuli is impaired in LBV and AD. However, patients with LBV are more impaired than patients with AD on tasks requiring remote memory for olfactory but not visual stimuli. The findings suggest that odor memory tasks may be useful in the assessment of LBV and AD.     

Are all subcortical dementias alike? Verbal learning and memory in Parkinson's and Huntington's disease patients

The utility of the concept of 'subcortical dementia' was investigated by comparing the verbal learning and memory abilities of Parkinson's disease (PD) patients with those of Huntington's disease (HD) patients. Many similarities between the PD and HD groups emerged, including impaired immediate memory spans, inconsistency of recall across learning trials, deficient use of a semantic clustering learning strategy, elevated intrusion rates on delayed recall, impaired recognition memory performance, normal retention of information over delay periods, normal vulnerability to proactive or retroactive interference, and normal types of intrusion errors. The HD subjects, however, displayed inferior free recall, deficient improvement across learning trials, abnormal serial position recall effects, higher perseveration rates, and supranormal improvement on recognition testing compared with free recall. Implications of these results for characterizing memory deficits associated with subcortical system dysfunction are discussed.     

Behavioral assessment of social competence following severe head injury

Abstract

The utility of the concept of «subcortical dementia» was investigated by comparing the verbal learning and memory abilities of Parkinson's disease (PD) patients with those of Huntington's disease (HD) patients. Many similarities between the PD and HD groups emerged, including impaired immediate memory spans, inconsistency of recall across learning trials, deficient use of a semantic clustering learning strategy, elevated intrusion rates on delayed recall, impaired recognition memory performance, normal retention of information over delay periods, normal vulnerability to proactive or retroactive interference, and normal types of intrusion errors. The HD subjects, however, displayed inferior free recall, deficient improvement across learning trials, abnormal serial position recall effects, higher perseveration rates, and supranormal improvement on recognition testing compared with free recall. Implications of these results for characterizing memory deficits associated with subcortical system dysfunction are discussed.     

The Category Cued Recall test in very mild Alzheimer's disease: discriminative validity and correlation with semantic memory functions

Episodic memory tests that measure cued recall may be particularly effective in the diagnosis of early Alzheimer's disease (AD) because they examine both episodic and semantic memory functions. The Category Cued Recall (CCR) test provides superordinate semantic cues at encoding and retrieval, and high discriminative validity has been claimed for this test. The aim of this study was to investigate the discriminative validity for this test when compared with the 10-word memory list from Alzheimer's Disease Assessment Scale (ADAS-cog) that measures free recall. The clinical diagnosis of AD was taken as the standard. It was also investigated whether the two episodic memory tests correlated with measures of semantic memory. The tests were administered to 35 patients with very mild AD (Mini Mental State Examination score > 22) and 28 control subjects. Both tests had high sensitivity (>88%) with high specificity (>89%). One out of the five semantic memory tests was significantly correlated to performances on CCR, whereas delayed recall on the ADAS-cog memory test was significantly correlated to two semantic tests. In conclusion, the discriminative validity of the CCR test and the ADAS-cog memory test was equivalent in very mild AD. This may be because CCR did not tap more semantic processes, which are impaired in the earliest phases of AD, than a test of free recall.     

A verbal memory test with high predictive accuracy for dementia of the Alzheimer type

The most common early deficit in patients with Alzheimer's disease (AD) is in recent memory. Distinguishing patients with AD from normal elderly individuals, using currently available memory tests, is limited by their lack of suitability for bedside use or for large-scale screening. We have devised a new memory test, a delayed word recall (DWR) test, that is both brief and efficient. It was designed specifically to maximize the likelihood of poor performance in patients with AD and minimize the likelihood of poor performance in normal elderly subjects. The DWR test uses required elaborative processing of to-be-remembered words and delayed free recall. Fifty-five normal elderly subjects and 28 patients with possible or probable AD were tested. The overall predictive accuracy of the DWR test was 95.2%. In addition, scores on the DWR test in normal subjects were not correlated with education or age. The inclusion of the DWR test in a previously studied cognitive detection battery for AD resulted in a considerable improvement in predictive accuracy.     

Semantic activation and implicit memory in Alzheimer disease

Patients with Alzheimer disease (AD) invariably display pronounced deficits in verbal memory when retention is tested explicitly. The present study examined the possibility that tasks which require memory only implicitly would be performed normally. Moderately demented patients with probable AD were severely impaired in free recall of a word list. On a subsequent word association test, the AD patients were less likely than normals to give items from the recall list as their word associations. The results suggest that implicit verbal memory, as well as explicit memory, is impaired in AD. While the magnitude of the activation effect was significantly reduced in AD patients, it was uncorrelated with recall performance or a measure of global cognitive functioning. Memory activation may thus depend on neural circuitry outside the traditional (i.e. temporo-limbic) memory system.     

Implicit, explicit, and semantic memory functions in Alzheimer's disease and Huntington's disease.

A priming task involving a word-stem completion paradigm was administered to patients with Alzheimer's disease (AD), patients with Huntington's disease (HD), and normal control subjects. The task was done under conditions of both implicit and explicit recall. Explicit and implicit recall were positively correlated in all three groups. After controlling for explicit recall ability through ANCOVA, AD patients were found to be normally susceptible to the effects of priming on implicit recall. HD patients, however, exhibited significantly increased susceptibility to priming, suggesting that they may have carried out the implicit task in a manner different from that of normals and AD patients. In a second experiment, AD patients were found to supply words of significantly lower association strength than the other two groups in a "free association" task using words from a published list of word association norms. This apparent degradation of semantic memory was found to be strongly correlated with explicit recall performance, suggesting that explicit, implicit, and semantic memory functions decline in parallel in AD. Results are discussed with respect to the difficulties inherent in attempts to demonstrate selective impairments of conceptually distinct forms of memory.     

Parsing the recognition memory components of the WMS-III face memory subtest: normative data and clinical findings in dementia groups

The WMS-III face memory subtest was developed as a quick, reliable, measure of non-verbal recognition memory. While the face memory subtest has demonstrated clinical sensitivity, the test has been criticized for low correlation with other WMS-III visual memory subtests and for failing to differentiate performance between clinical groups. One possible reason for these findings may be due to the impact of response bias associated with recognition memory tests. Four studies were conducted to evaluate the utility of applying signal detection measures to the face memory subtests. The first two studies used the WMS-III standardization data set to determine age and education effects and to present normative and reliability data for hits, false positives, discriminability and response bias. The third study tested the hypothesis that using response components and signal detection measures would enhance the correlation between face memory and the other WMS-III visual memory subtests. The fourth study compared performance of patients with Alzheimer's disease, Huntington's disease, Korsakoff's syndrome and demographically matched controls on the new face memory scores. The new measures did not have higher correlation with other WMS-III visual memory measures than the standard scoring of the test. Analysis of the clinical samples indicated that the discriminability index best differentiated patients from controls. The response components, particularly delayed false positives, differentiated performance among the clinical groups. Normative and reliability data are presented.     

Alzheimer's disease and feeling-of-knowing in episodic memory

Episodic memory feeling-of-knowing (FOK) was examined in 16 patients with Alzheimer’s disease (AD), 16 elderly participants, and 16 younger adults. Participants were given cued recall and recognition tests of 20 critical cue-target words. Subsequently, they judged their FOK for non-recalled words in terms of how likely they thought they would be to recognize the keywords on a subsequent recognition test. The results indicated dementia-related deficits on both the recall and recognition tests. Compared to older adults, AD patients exhibited impaired FOK accuracy. This pattern of outcome indicates that early AD is associated with a deficit in episodic memory and a deficit in memory monitoring for newly learned information. Furthermore, our observation revealed that in AD, episodic memory may be a more important factor than executive function in explaining the FOK inaccuracy.     

The diagnostic accuracy of an incidental memory modification of the Boston Naming Test (memo-BNT) in differentiating between normal aging and mild Alzheimer's disease

Early Alzheimer's disease (AD) is associated with deficits in episodic memory. Semantic memory and naming have also been found to be affected, although to a lesser degree than episodic memory. Most episodic memory tests used in clinical settings assess intentional memory. The aim of the present paper was to present an incidental memory modification of the Boston Naming Test (memo-BNT) and to study the diagnostic accuracy of the BNT and the memo-BNT in differentiating between healthy old controls and AD patients. There were three groups in the study: 22 young controls (mean age 21.7), 23 normally aged old controls (mean age 70.6), and 23 patients with mild AD (mean age 74.0). There were no differences in the memo-BNT test scores between the old and young control participants. There were, however, significant differences between the AD patients and both control groups in several of the memo-BNT measures. Incidental free recall was the best measure in discriminating between the healthy aged controls and the AD patients (AUC?=?.939) and it had a better diagnostic accuracy than naming (AUC?=?880). The results indicate that the memo-BNT could be used in clinical settings especially to differentiate between normal aging and mild AD.     

The diagnostic accuracy of an incidental memory modification of the Boston Naming Test (memo-BNT) in differentiating between normal aging and mild Alzheimer's disease

Early Alzheimer's disease (AD) is associated with deficits in episodic memory. Semantic memory and naming have also been found to be affected, although to a lesser degree than episodic memory. Most episodic memory tests used in clinical settings assess intentional memory. The aim of the present paper was to present an incidental memory modification of the Boston Naming Test (memo-BNT) and to study the diagnostic accuracy of the BNT and the memo-BNT in differentiating between healthy old controls and AD patients. There were three groups in the study: 22 young controls (mean age 21.7), 23 normally aged old controls (mean age 70.6), and 23 patients with mild AD (mean age 74.0). There were no differences in the memo-BNT test scores between the old and young control participants. There were, however, significant differences between the AD patients and both control groups in several of the memo-BNT measures. Incidental free recall was the best measure in discriminating between the healthy aged controls and the AD patients (AUC = .939) and it had a better diagnostic accuracy than naming (AUC = 880). The results indicate that the memo-BNT could be used in clinical settings especially to differentiate between normal aging and mild AD.     

Declarative and Procedural Learning,Quantitative Measures of the Hippocampus,and Subcortical White Alterations in Alzheimer's Disease and Ischaemic Vascular Dementia

This research investigated whether subjects with Alzheimer's disease (AD) and ischaemic vascular dementia (IVD) associated with periventricular and deep white matter alterations can be dissociated on tests of declarative and procedural memory, as well as on MRI indices of white matter alterations and the size of the hippocampal formation. The California Verbal Learning Test (CVLT) and the Pursuit Rotor Learning Tests (PRLT) were used to measure declarative and procedural memory, respectively. Subjects with IVD obtained a higher score on the CVLT recognition discriminability index; however, on the PRLT total time on target, carry-over between trial blocks, and slope calculated for all test trials was low. Subjects with AD exhibited the opposite profile. MRI studies indicated that subjects with IVD had considerably greater white matter alterations, but larger hippocampal formations than subjects with AD. Higher scores on the CVLT recognition discriminability index were correlated with increased size of the body of the hippocampus and parahippocampal gyrus. By contrast, as the severity of white matter alterations increased the slope on the PRLT declined. In sum, subjects with AD and IVD can be dissociated on the basis of differing patterns of impairment on tests of declarative and procedural memory, and MRI indices of white matter alteration and the integrity of the hippocampal formation.     

Utility of California Verbal Learning Test, Second Edition, recall discriminability indices in the evaluation of traumatic brain injury.

The performance of 23 patients with moderate-severe traumatic brain injury on the California Verbal Learning Test, Second Edition (CVLT-II; Delis et al., 2000) was compared with that of 23 matched healthy controls to determine whether recall discriminability indices, which take into account both correct target recall and intrusive errors, would provide better diagnostic classification than traditional variables that are based exclusively on correct recall. Patients with traumatic brain injury recalled fewer correct words, and also made more intrusive errors, on CVLT-II short and long delay, free and cued recall trials (p < .02 for all variables after Stepdown Bonferroni correction). However, recall discriminability indices yielded a classification of clinical versus control participants (72%) that was not significantly different from one based on traditional variables (74%). We conclude that CVLT-II recall discriminability indices do not routinely provide an advantage over traditional variables in patients with traumatic brain injury.