Visual Perceptual Organization Ability in Autopsy-Verified Dementia with Lewy Bodies and Alzheimer's Disease.

OBJECTIVES: Prominent impairment of visuospatial processing is a feature of dementia with Lewy bodies (DLB), and diagnosis of this impairment may help clinically distinguish DLB from Alzheimer's disease (AD). The current study compared autopsy-confirmed DLB and AD patients on the Hooper Visual Organization Test (VOT), a test that requires perceptual and mental reorganization of parts of an object into an identifiable whole. The VOT may be particularly sensitive to DLB since it involves integration of visual information processed in separate dorsal and ventral visual "streams". METHODS: Demographically similar DLB (n=28), AD (n=115), and normal control (NC; n=85) participants were compared on the VOT and additional neuropsychological tests. Patient groups did not differ in dementia severity at time of VOT testing. High and Low AD-Braak stage DLB subgroups were compared to examine the influence of concomitant AD pathology on VOT performance. RESULTS: Both patient groups were impaired compared to NC participants. VOT scores of DLB patients were significantly lower than those of AD patients. The diagnostic sensitivity and specificity of the VOT for patients versus controls was good, but marginal for DLB versus AD. High-Braak and low-Braak DLB patients did not differ on the VOT, but High-Braak DLB performed worse than Low-Braak DLB on tests of episodic memory and language. CONCLUSIONS: Visual perceptual organization ability is more impaired in DLB than AD but not strongly diagnostic. The disproportionate severity of this visual perceptual deficit in DLB is not related to degree of concomitant AD pathology, which suggests that it might primarily reflect Lewy body pathology. (JINS, 2016, 22, 609-619).

Accounting for functional loss in Alzheimer's disease and dementia with Lewy bodies: beyond cognition.

BACKGROUND: The relative contributions of cognitive, motor, and behavioral deficits to the impairment of physical or instrumental activities of daily living (ADLs) may differ in patients with dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). METHODS: Multiple linear regression analyses were used to identify the amount of variability in physical self-maintenance and instrumental ADL ratings predicted by cognitive, motor, and behavioral indices separately for patients with autopsy-diagnosed DLB (n = 39) or AD (n = 39). RESULTS: Motor dysfunction accounted for significant variance in physical ADLs in DLB (R(2) change = 0.17), whereas behavioral (R(2) change = 0.23) and motor dysfunction (R(2) change = 0.13) accounted for significant variance in AD. Motor (R(2) change = 0.32) and cognitive (R(2) change = 0.10) dysfunction accounted for significant variance in instrumental ADLs in DLB, whereas cognitive (R(2) change = 0.36) and behavioral (R(2) change = 0.12) dysfunction accounted for significant variance in AD. CONCLUSIONS: Cognitive, motor, and behavioral deficits contribute differently to ADL changes in DLB and AD. Thus, treatments designed to ameliorate a certain aspect of AD or DLB (e.g., cognitive dysfunction) may have a larger impact on everyday functioning in one disorder than the other.

Neuropsychiatric features of frontal lobe dysfunction in autopsy-confirmed patients with lewy bodies and "pure" Alzheimer disease.

OBJECTIVE: To compare patients with autopsy-confirmed Alzheimer disease (AD) and dementia with Lewy bodies (DLB) on the frequency of behaviors related to frontal system dysfunction and the association of these behaviors with dementia severity. METHODS: We performed a cross-sectional survey of a longitudinal cohort at a university research center for AD on a volunteer sample of 19 DLB and 38 AD participants with autopsy-confirmed diagnoses, similar in age (DLB: 77.3, AD: 77.5), education (DLB: 15.2, AD: 14.7), and Mini-Mental State Examination (MMSE) score (DLB: 20.6, AD: 20.5), with impairment ranging from mild deficits to moderate dementia. The Frontal Systems Behavior Scale (FrSBe)-Family Rating Form assessing patient apathy, disinhibition, and executive dysfunction by a knowledgeable informant was used. RESULTS: A two-way analysis of variance with the FrSBe total as the dependent variable revealed a significant MMSE by diagnosis interaction (F(1,53) = 9.34, p = 0.004). Mean FrSBe total for AD patients showed significant impairment across the range of dementia severity, whereas it was relatively preserved for DLB patients in the early stage of disease. The interaction term showed the same pattern for the executive dysfunction (F(1,53) = 7.62, p = 0.008), disinhibition (F(1,53) = 4.90, p = 0.031), and apathy (F(1,53) = 9.77, p = 0.003) subscales. CONCLUSION: Although frontal behavioral symptoms in AD patients were present regardless of stage of dementia, DLB patients showed significant frontal dysfunction only in later stages. Results suggest that frontal subcortical circuits associated with behaviors assessed by the FrSBe are affected early in AD but not until later stages in DLB. Assessing specific behaviors related to frontal systems, coupled with stage of cognitive decline, may aid in clinical differentiation of AD and DLB.

Proof-of-concept for characterization of neurodegenerative disorders utilizing two non-REM sleep biomarkers.

Study objective: This proof-of-concept study aimed to determine whether the combined features of two non-rapid eye movement (NREM) sleep biomarkers acquired predominantly in-home could characterize different neurodegenerative disorders. Methods: Sleep spindle duration and non-REM hypertonia (NRH) were evaluated in seven groups including a control group (CG = 61), and participants with isolated REM sleep behavior disorder (iRBD = 19), mild cognitive impairment (MCI = 41), Parkinson disease (PD = 16), Alzheimer disease dementia (ADem = 29), dementia with Lewy Bodies or Parkinson disease dementia (LBD = 19) and progressive supranuclear palsy (PSP = 13). One-way analysis of variance (ANOVA), Mann-Whitney U, intra-class (ICC) and Spearman ranked correlations, Bland-Altman plots and Kappa scores, Chi-square and Fisher exact probability test, and multiple-logistic regression were focused primarily on spindle duration and NRH and the frequencies assigned to the four normal/abnormal spindle duration/NRH combinations. Results: ANOVA identified group differences in age, sleep efficiency, REM, NRH (p < 0.0001) and sleep time (p = 0.015), Spindle duration and NRH each demonstrated good night-to-night reliabilities (ICC = 0.95 and 0.75, Kappa = 0.93 and 0.66, respectively) and together exhibited an association in the PD and LBD groups only (p < 0.01). Abnormal spindle duration was greater in records of PSP (85%) and LBD (84%) patients compared to CG, MCI, PD and ADem (p < 0.025). Abnormal NRH was greater in PSP = 92%, LBD = 79%, and iRBD = 74% compared to MCI = 32%, ADem = 17%, and CG = 16% (p < 0.005).The combination biomarker normal spindle duration/normal NRH was observed most frequently in CG (56%) and MCI (41%). ADem most frequently demonstrated normal spindle duration/normal NRH (45%) and abnormal spindle duration/normal NRH (38%). Normal spindle duration/abnormal NRH was greatest in iRBD = 47%, while abnormal spindle duration/abnormal NRH was predominant in PSP = 85% and LBD = 74%. Conclusion: The NREM sleep biomarkers spindle duration and NRH may be useful in distinguishing patients with different neurodegenerative disorders. Larger prospective cohort studies are needed to determine whether spindle duration and NRH can be combined for prodromal assessment and/or monitoring disease progression.

Autonomic dysregulation during sleep in Parkinsonian spectrum disorders - A proof of concept.

INTRODUCTION: Autonomic dysfunction is common in α-synucleinopathies such as Lewy Body dementias (LBD), Parkinson's disease (PD), and isolated REM Sleep Behavior Disorder (iRBD). We analyzed pulse-rate changes during sleep to index autonomic nervous system (ANS) dysfunction in patients with α-synucleinopathies vs. non-synucleinopathy groups expected to have normal ANS function. METHODS: Patients with LBD (n = 16), PD (PD, n = 14) or iRBD (n = 12) were compared to the non-synucleinopathy groups Alzheimers disease dementia (ADem, n = 26), mild cognitive impairment (MCI, n = 34) or controls (CG, n = 54). Sleep Profiler was used to derive a sleep autonomic activation index (AAI), i.e., ≥6 beat-per-minute increase/decrease, pulse rate coefficient of variation (PR-CV), and automated sleep staging with sleep-spindles and non-REM hypertonia (NRH). Analysis included statistical group comparisons and receiver operating characteristics curves to determine optimal classification of groups. RESULTS: AAI and PR-CV were moderately correlated across all recordings (rs = 0.58, P < 0.0001), except in the LBD and PD groups. AAI but not PR-CV differentiated the LBD, PD and iRBD from non-Parkinsonian groups. AAI was decreased in LBD and PD patients compared to the CG (p < 0.003) and MCI (p < 0.03). AAI decreased based on age and its receiver operating characteristic area under the curve ranged from 0.63 to 0.75. AAI had a weak negative correlation to NRH (rs ≤ -0.26) but not sleep-spindles. CONCLUSION: Synucleinopathy-related ANS dysfunction can reasonably discriminate prodromal and manifest PD/LBD diseased groups from non-synucleinopathies. Further studies incorporating AAI into a multivariate classifier of neurodegenerative disorders based on sleep characteristics acquired in the patient's home are planned.

Early visuospatial deficits predict the occurrence of visual hallucinations in autopsy-confirmed dementia with Lewy bodies.

OBJECTIVES: The current study explored the value of visuospatial findings for predicting the occurrence of visual hallucinations (VH) in a sample of patients with dementia with Lewy bodies (DLB) compared with patients with Alzheimer disease (AD). PARTICIPANTS/MEASUREMENTS: Retrospective analysis of 55 autopsy-confirmed DLB and 55 demographically similar, autopsy-confirmed AD cases determined whether severe initial visuospatial deficits on the WISC-R Block Design subtest predicted the development of VH. Visuospatial deficits were considered severe if Block Design z scores were 2.5 or more standard deviations below the mean of a well-characterized normal control group (severe visuospatial deficits [severe-VIS]; DLB: n = 35, AD: n = 26) and otherwise were considered mild (mild visuospatial deficits [mild-VIS]; DLB: n = 20, AD: n = 29). RESULTS: Forty percent of the severe-VIS DLB group had baseline VH compared with 0% of mild-VIS DLB patients. Only 8% of the severe-VIS and 3% mild-VIS AD patients had baseline VH. During the follow-up period (mean = 5.0 years), an additional 61% of the severe-VIS but only 11% of the mild-VIS DLB patients developed VH. In that period, 38% of the severe-VIS and 20% of the mild-VIS AD patients developed VH. After considering initial MMSE score and rate of decline, logistic regression analyses found that performance on Block Design significantly predicted the presence of VH in the DLB group but not the AD group. CONCLUSIONS: The presence of early, severe deficits on neuropsychological tests of visuospatial skill increases the likelihood that patients with suspected DLB will develop the prototypical DLB syndrome. The presence of such deficits may identify those DLB patients whose syndrome is driven by α-synuclein pathology rather than AD pathology and may inform treatment plans as well as future research.

Perception of Fragmented Letters by Patients With Pathologically Confirmed Dementia With Lewy Bodies or Alzheimer Disease.

BACKGROUND AND OBJECTIVE: Patients with dementia with Lewy bodies perform worse than those with Alzheimer disease (AD) on tests of visual perception, but the clinical utility of these tests remains unknown because studies often had clinically diagnosed groups that may inadvertently cross-contaminate Lewy body disease (LBD) with pure AD pathology, used experimental tests not easily adaptable for clinical use, and had no way to examine relationships between the severity of LBD pathology and degree of cognitive impairment. Therefore, we sought to determine whether performance on a widely used clinical test of visuoperceptual ability effectively differentiates between patients with autopsy-confirmed LBD or AD and correlates with the severity of LBD pathology. METHODS: Patients with mild to moderate dementia (n = 42) and cognitively healthy controls (n = 22) performed a Fragmented Letters Test in which they identified letters of the alphabet that were randomly visually degraded by 70% and additional visuospatial and episodic memory tests. At autopsy, dementia cases were confirmed to have LBD (n = 19), all with concomitant AD, or only AD (n = 23). Severity of α-synuclein pathology in the hippocampus and neocortex was rated on an ordinal scale. RESULTS: Patients with LBD performed worse than those with AD (B = -2.80 ± 0.91, p = 0.009) and healthy controls (B = -3.34 ± 1.09, p = 0.01) on the Fragmented Letters Test after adjustment for age, sex, education, Mini-Mental State Examination score, and ability to name intact letters. Patients with AD did not differ from controls (B = -0.55 ± 1.08, p = 0.87). The test effectively distinguished between patients with LBD or AD with 73% sensitivity and 87% specificity, and the area under the curve in receiver operating characteristic analyses was 0.85 (95% CI 0.72-0.95), higher than for standard tests of visuospatial ability (Block Design; 0.72; CI 0.35-0.75) or memory (California Verbal Learning Test, trials 1-5; 0.55; CI 0.57-0.88). Fragmented Letters Test scores were negatively correlated with LBD pathology density ratings in hippocampus and neocortical regions (Spearman rs = -0.53 to -0.69). DISCUSSION: Fragmented Letters Test performance can effectively differentiate patients with LBD pathology from those with only AD pathology at a mild to moderate stage of dementia, even when LBD occurs with significant concomitant AD pathology, and may also be useful for gauging the severity of cortical α-synuclein pathology in those with LBD.

Non-REM sleep with hypertonia in Parkinsonian Spectrum Disorders: A pilot investigation.

INTRODUCTION: From an ongoing multicenter effort toward differentiation of Parkinsonian spectrum disorders (PSD) from other types of neurodegenerative disorders, the sleep biomarker non-rapid-eye-movement sleep with hypertonia (NRH) emerged. METHODS: This study included in the PSD group patients with dementia with Lewy bodies/Parkinson disease dementia (DLB/PDD = 16), Parkinson disease (PD = 16), and progressive supranuclear palsy (PSP = 13). The non-PSD group included patients with Alzheimer disease dementia (AD = 24), mild cognitive impairment (MCI = 35), and a control group with normal cognition (CG = 61). In-home, multi-night Sleep Profiler studies were conducted in all participants. Automated algorithms detected NRH, characterized by elevated frontopolar electromyographic power. Between-group differences in NRH were evaluated using Logistic regression, Mann-Whitney U and Chi-squared tests. RESULTS: NRH was greater in the PSD group compared to non-PSD (13.9 ± 11.0% vs. 3.1 ± 4.7%, P < 0.0001). The threshold NRH≥5% provided the optimal between-group differentiation (AUC = 0.78, P < 0.001). NRH was independently associated with the PSD group after controlling for age, sex, and SSRI/SNRI use (P < 0.0001). The frequencies of abnormal NRH by subgroup were PSP = 92%, DLB/PDD = 81%, PD = 56%, MCI = 26%, AD = 17%, and CG = 16%. The odds of abnormal NRH in each PSD subgroup ranged from 3.7 to 61.2 compared to each non-PSD subgroup. The night-to-night and test-retest intraclass correlations were excellent (0.78 and 0.84, both P < 0.0001). CONCLUSIONS: In this pilot study, NRH appeared to be a novel candidate sleep biomarker for PSD-related neurodegeneration. Future studies in larger cohorts are needed to confirm these findings, understand the etiology of NRH magnitude/duration, and determine whether it is an independent prodromal marker for specific neurodegenerative pathologies.

Cognitive and functional decline in Huntington's disease: dementia criteria revisited.

The importance of designating criteria for diagnosing dementia lies in its implications for clinical treatment, research, caregiving, and decision-making. Dementia diagnosis in Huntington's disease (HD) is often based on criteria developed for Alzheimer's disease requiring memory loss. However, it is likely that other cognitive deficits contribute to functional impairment in HD before memory declines. The goal is to identify cognitive deficits that contribute to functional impairment to support dementia criteria that reflect HD neuropathology. Eighty-four HD mutation-positive subjects completed neuropsychological tests and the Unified Huntington's Disease Rating Scale Functional Independence Scale (FIS). Functional impairment was defined as 80 or below on the FIS. Speed of processing, initiation, and attention measures accounted for 70.0% of the variance in FIS ratings (linear regression) and correctly classified 91.7% of subjects as functionally impaired or intact (logistic regression). Measures of memory, motor impairment except dysarthria, neuroleptic use, and depressed mood did not improve prediction. A definition of HD dementia that includes cognitive impairment in at least two areas of cognition but does not require a memory deficit, in the context of impaired functional abilities and a deteriorating course, more accurately reflects HD neuropathology and could lead to improved research methods and patient care.

Head Position During Sleep: Potential Implications for Patients with Neurodegenerative Disease.

BACKGROUND: The characterization of sleep in those with neurodegenerative disease (NDD) is essential in understanding the potential neurobiological mechanisms that underlie the connection between sleep disruption and NDD manifestations and progression. OBJECTIVE: Explore the inter-relationships between NDD and age, sex, diagnosis of obstructive sleep apnea, snoring, and duration of sleep time with the head in the supine and non-supine positions. METHODS: A case-control design was used to evaluate differences in sleep position obtained from multi-night, in-home Sleep Profiler recordings in 45 patients with diagnosed NDD (24 with mild cognitive impairment, 15 with Alzheimer's disease, and 6 with Lewy Body, Parkinson's, or other dementias) and 120 age-sex matched controls with normal cognition (NC). RESULTS: The frequency of supine sleep >2 h/night was significantly greater in the NDD than in the NC group (p < 0.001, odds ratio = 3.7), and remained significant after controlling for age, sex, snoring, and obstructive sleep apnea diagnosis (p = 0.01). There were no group differences in nocturnal mobility i.e., number of head position changes/h. CONCLUSION: This study demonstrates the utility of in-home measurements of sleep in defining the association of supine sleep position with neurodegenerative disorders. Our findings warrant further investigation, particularly in light of the recent evidence suggesting that sleep may an active role in the brain's ability to clear CNS neurotoxins and metabolites.

Visuospatial deficits predict rate of cognitive decline in autopsy-verified dementia with Lewy bodies.

Dementia with Lewy bodies (DLB) is often characterized by pronounced impairment in visuospatial skills, attention, and executive functions. However, the strength of the phenotypic expression of DLB varies and may be weaker in patients with extensive concomitant Alzheimer's disease (AD). To determine whether strength of the DLB clinical phenotype impacts cognitive decline, visuospatial and language tests were retrospectively used to predict 2-year rate of global cognitive decline in 22 autopsy-confirmed DLB patients (21 with concomitant AD) and 44 autopsy-confirmed "pure" AD patients. Generalized estimating equations (GEE) revealed a significant interaction such that poor baseline performances on tests of visuospatial skills were strongly associated with a rapid rate of cognitive decline in DLB but not AD (p < .001). No effect of confrontation naming was found. DLB patients with poor visuospatial skills had fewer neurofibrillary tangles and were more likely to experience visual hallucinations than those with better visuospatial skills. These results suggest that the severity of visuospatial deficits in DLB may identify those facing a particularly malignant disease course and may designate individuals whose clinical syndrome is impacted more by Lewy body formation than AD pathology.

Neocortical disconnectivity disrupts sensory integration in Alzheimer's disease.

The cortical pathology in Alzheimer's disease (AD) should lead to the loss of effective interaction between distinct neocortical areas. This study compared 2 conditions within a single sensory integration task that differed in the demands placed on effective cross-cortical interaction. AD patients were impaired in their ability to bind distinct visual features of a stimulus when this binding placed greater demands on cross-cortical interaction (i.e., motion and color) but were not impaired when this binding placed lesser demands on such interaction (i.e., motion and luminance). In contrast, neurologically intact individuals and patients with Huntington's disease were able to effectively bind features under both conditions. These results provide psychophysical support for the presence of functional disconnectivity in AD and demonstrate the utility of AD for investigating the neurocognitive substrates of sensory integration.

Motion discrimination in dementia with Lewy bodies and Alzheimer disease.

OBJECTIVE: Visual processing abilities of patients with dementia with Lewy bodies (DLB) or Alzheimer disease (AD) dementia were assessed psychophysically using a simple horizontal motion discrimination task that engages the dorsal visual processing stream. METHODS: Participants included patients with mild dementia with DLB, AD dementia or Parkinson disease (PD) with dementia (PDD), without dementia with PD, and normal controls. Participants indicated the left or right direction of coherently moving dots that were embedded within dynamic visual noise provided by randomly moving dots. The proportion of coherently moving dots was increased or decreased across trials to determine a threshold at which participants could correctly indicate their direction with greater than 80% accuracy. RESULTS: Motion discrimination thresholds of patients with DLB and PDD were comparable and significantly higher (i.e., worse) than those of patients with AD dementia. The thresholds of patients with AD dementia and patients with PD were normal. These results were confirmed in subgroups of patients with DLB/PDD and AD dementia with autopsy-confirmed disease. A motion discrimination threshold greater than 0.23 distinguished between DLB/PDD and AD dementia with 67% sensitivity and 85% specificity. CONCLUSIONS: Differential deficits in detecting direction of simple horizontal motion suggest that dorsal processing stream dysfunction is greater in DLB and PDD than in AD dementia. Therefore, impaired performance on simple visual motion discrimination tasks that specifically engage occipitoparietal brain regions suggests the presence of Lewy body pathology.

Recognition memory span in autopsy-confirmed Dementia with Lewy Bodies and Alzheimer's Disease.

Evidence from patients with amnesia suggests that recognition memory span tasks engage both long-term memory (i.e., secondary memory) processes mediated by the diencephalic-medial temporal lobe memory system and working memory processes mediated by fronto-striatal systems. Thus, the recognition memory span task may be particularly effective for detecting memory deficits in disorders that disrupt both memory systems. The presence of unique pathology in fronto-striatal circuits in Dementia with Lewy Bodies (DLB) compared to AD suggests that performance on the recognition memory span task might be differentially affected in the two disorders even though they have quantitatively similar deficits in secondary memory. In the present study, patients with autopsy-confirmed DLB or AD, and Normal Control (NC) participants, were tested on separate recognition memory span tasks that required them to retain increasing amounts of verbal, spatial, or visual object (i.e., faces) information across trials. Results showed that recognition memory spans for verbal and spatial stimuli, but not face stimuli, were lower in patients with DLB than in those with AD, and more impaired relative to NC performance. This was despite similar deficits in the two patient groups on independent measures of secondary memory such as the total number of words recalled from long-term storage on the Buschke Selective Reminding Test. The disproportionate vulnerability of recognition memory span task performance in DLB compared to AD may be due to greater fronto-striatal involvement in DLB and a corresponding decrement in cooperative interaction between working memory and secondary memory processes. Assessment of recognition memory span may contribute to the ability to distinguish between DLB and AD relatively early in the course of disease.

Visual search in Dementia with Lewy Bodies and Alzheimer's disease.

Visual search is an aspect of visual cognition that may be more impaired in Dementia with Lewy Bodies (DLB) than Alzheimer's disease (AD). To assess this possibility, the present study compared patients with DLB (n = 17), AD (n = 30), or Parkinson's disease with dementia (PDD; n = 10) to non-demented patients with PD (n = 18) and normal control (NC) participants (n = 13) on single-feature and feature-conjunction visual search tasks. In the single-feature task participants had to determine if a target stimulus (i.e., a black dot) was present among 3, 6, or 12 distractor stimuli (i.e., white dots) that differed in one salient feature. In the feature-conjunction task participants had to determine if a target stimulus (i.e., a black circle) was present among 3, 6, or 12 distractor stimuli (i.e., white dots and black squares) that shared either of the target's salient features. Results showed that target detection time in the single-feature task was not influenced by the number of distractors (i.e., "pop-out" effect) for any of the groups. In contrast, target detection time increased as the number of distractors increased in the feature-conjunction task for all groups, but more so for patients with AD or DLB than for any of the other groups. These results suggest that the single-feature search "pop-out" effect is preserved in DLB and AD patients, whereas ability to perform the feature-conjunction search is impaired. This pattern of preserved single-feature search with impaired feature-conjunction search is consistent with a deficit in feature binding that may be mediated by abnormalities in networks involving the dorsal occipito-parietal cortex.

Time perspective and health-promoting behavior in a cardiac rehabilitation population.

Behavior changes can significantly improve outcomes for patients in the cardiac rehabilitation population. The authors examined the influence of time perspectives on health-promoting behaviors of patients for whom the future might be perceived as limited, although goal-directed behavior changes are crucial. Measures included the Zimbardo Time Perspective Inventory and the Health-Promoting Lifestyle Profile II (HPLPII). In this study of 74 cardiac participants with a mean age of 60.2 years, the preponderant time perspective was found to be past-positive orientation. The authors discuss the effects of a life-threatening event and older age on time perspective and health-promoting behaviors and consequent implications for cardiac rehabilitation programs.

Behavioral measures of saccade latency and inhibition in manifest and premanifest Huntington's disease.

Initiation and inhibition of saccadic eye movements has been shown to be impaired in patients with Huntington's disease (HD) and premanifest gene carriers (PMGC), and may provide biomarkers useful in tracking phenotypic change. Computerized behavioral tests of prosaccade latency and disinhibition presented to 31 non-gene carriers (NGC), 25 PMGC, and 12 HD patients. These tests provided quantitative performance measures without use of eye-tracking equipment. Significant differences on saccade tests were found, with PMGC intermediate between NGC and HD patients. Saccade latency discriminated PMGC from NGC, whereas saccade disinhibition discriminated PMGC from HD patients. Results suggest utility of behavioral saccade measures as premanifest indicators of phenoconversion in HD.

Verbal learning and memory in patients with dementia with Lewy bodies or Parkinson's disease with dementia.

This study compared verbal learning and memory in patients with autopsy-confirmed dementia with Lewy bodies (DLB) and patients with Parkinson's disease with dementia (PDD). A total of 24 DLB patients, 24 PDD patients, and 24 normal comparison participants were administered the California Verbal Learning Test. The three groups were matched on demographic variables, and the two patient groups were matched on the Mattis Dementia Rating Scale. The results indicated that DLB patients recalled less information than PDD patients on all but one recall measure and displayed a more rapid rate of forgetting. In contrast, the PDD patients committed a greater percentage of perseveration errors than the DLB patients. The two groups did not differ in the percentage of recall intrusion errors or any measures of recognition. A discriminant function analysis (DFA) using short-delay cued recall, percentage of perseveration errors, and List B recall differentiated the DLB and PDD groups with 81.3% accuracy. The application of the DFA algorithm to another sample of 42 PDD patients resulted in a 78.6% correct classification rate. The results suggest that, despite equivalent levels of general cognitive impairment, patients with DLB or PDD exhibit a different pattern of verbal learning and memory deficits.

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.

The myth of testing construct validity using factor analysis or correlations with normal or mixed clinical populations: lessons from memory assessment.

For nearly a century, the primary method employed by psychologists to define and test the validity of constructs evaluated by assessment instruments has been shared-variance techniques such as intervariable correlations or factor analysis with large normative or mixed clinical samples. To illustrate the shortcomings of this approach, we conducted (1) correlational analyses of immediate- and delayed-memory measures separately in normal participants and in homogeneous samples of patients with either Alzheimer's disease or Huntington's disease; and (2) factor analysis of immediate and delayed-recall and recognition measures in a large, homogeneous sample of patients with Alzheimer's disease. The findings revealed that cognitive measures that share variance in the intact brain-thereby giving the facade of assessing a unitary construct-can dissociate and contribute to unique variance in the damaged brain, but only if the pathology occurs in brain regions known to disrupt vital cognitive processes tapped by those measures. The results illustrate that shared-variance procedures applied to normal or mixed clinical populations can mask some of the most vital cognitive constructs, such as the classic distinction between short- and long-term memory. Implications of these findings for research and clinical practice are discussed.