Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia

Digital quantification of the MMSE interlocking pentagon areas: a three-stage algorithm

The Mini-Mental State Examination (MMSE) is a widely employed screening tool for the severity of cognitive impairment. Among the MMSE items, the pentagon copying test (PCT) requires participants to accurately replicate a sample of two interlocking pentagons. While the PCT is traditionally scored on a binary scale, there have been limited developments of granular scoring scale to assess task performance. In this paper, we present a novel three-stage algorithm, called Quantification of Interlocking Pentagons (QIP) which quantifies PCT performance by computing the areas of individual pentagons and their intersection areas, and a balance ratio between the areas of the two individual pentagons. The three stages of the QIP algorithm include: (1) detection of line segments, (2) unraveling of the interlocking pentagons, and (3) quantification of areas. A set of 497 PCTs from 84 participants including their baseline and follow-up PCTs from the Rush Memory and Aging Project was selected blinded about their cognitive and clinical status. Analysis of the quantified data revealed a significant inverse relationship between age and balance ratio (beta = - 0.49, p = 0.0033), indicating that older age was associated with a smaller balance ratio. In addition, balance ratio was associated with perceptual speed (r = 0.71, p = 0.0135), vascular risk factors (beta = - 3.96, p = 0.0269), and medical conditions (beta = - 2.78, p = 0.0389). The QIP algorithm can serve as a useful tool for enhancing the scoring of performance in the PCT.

Neuropsychological differential diagnosis of Alzheimer's disease and vascular dementia: a systematic review with meta-regressions

Introduction

Diagnostic classification systems and guidelines posit distinguishing patterns of impairment in Alzheimer's (AD) and vascular dementia (VaD). In our study, we aim to identify which diagnostic instruments distinguish them.

Methods

We searched PubMed and PsychInfo for empirical studies published until December 2020, which investigated differences in cognitive, behavioral, psychiatric, and functional measures in patients older than 64 years and reported information on VaD subtype, age, education, dementia severity, and proportion of women. We systematically reviewed these studies and conducted Bayesian hierarchical meta-regressions to quantify the evidence for differences using the Bayes factor (BF). The risk of bias was assessed using the Newcastle-Ottawa-Scale and funnel plots.

Results

We identified 122 studies with 17,850 AD and 5,247 VaD patients. Methodological limitations of the included studies are low comparability of patient groups and an untransparent patient selection process. In the digit span backward task, AD patients were nine times more probable (BF = 9.38) to outperform VaD patients (β g = 0.33, 95% ETI = 0.12, 0.52). In the phonemic fluency task, AD patients outperformed subcortical VaD (sVaD) patients (β g = 0.51, 95% ETI = 0.22, 0.77, BF = 42.36). VaD patients, in contrast, outperformed AD patients in verbal (β g = -0.61, 95% ETI = -0.97, -0.26, BF = 22.71) and visual (β g = -0.85, 95% ETI = -1.29, -0.32, BF = 13.67) delayed recall. We found the greatest difference in verbal memory, showing that sVaD patients outperform AD patients (β g = -0.64, 95% ETI = -0.88, -0.36, BF = 72.97). Finally, AD patients performed worse than sVaD patients in recognition memory tasks (β g = -0.76, 95% ETI = -1.26, -0.26, BF = 11.50).

Conclusion

Our findings show inferior performance of AD in episodic memory and superior performance in working memory. We found little support for other differences proposed by diagnostic systems and diagnostic guidelines. The utility of cognitive, behavioral, psychiatric, and functional measures in differential diagnosis is limited and should be complemented by other information. Finally, we identify research areas and avenues, which could significantly improve the diagnostic value of cognitive measures.

The nature of the task stimuli affects graphic perseveration severity: Insights from a single case study

OBJECTIVE

Graphic perseveration in target-cancellation tasks has been frequently described in patients with right brain damage and unilateral spatial neglect. Conversely, among patients with dementia, the spontaneous production of complex graphic perseverations, as well as their triggers and modulating factors, have been poorly understood. Here we describe the case of RM, a patient with Alzheimer's dementia, who produced a rich pattern of complex graphic perseverations at target-cancellation tasks, especially with abstract target stimuli, i.e., lines.

METHOD

We developed an ad-hoc behavioral paradigm to investigate patient RM's performance at two versions of a target-cancellation task: fork-cancellation and line-cancellation. In both versions, RM was asked to cross the blue targets, while crossing a red target was considered a false alarm, as a proxy of incorrect response inhibition capacity. Moreover, we classified the presence and intensity of two other graphic perseverative behaviors, i.e., additional marks and scribble perseveration.

RESULTS

Complex graphic perseverations and false alarms were more frequent in the line-compared to the fork-cancellation trials. Conversely, the semantic nature of the task did not differentially modulate the occurrence of additional marks and scribble perseverations.

CONCLUSIONS

We argue that the breakdown of RM's executive functioning at the semantic-representational level was a prerequisite for such complex graphic perseverations to occur. Furthermore, we provide hints on the potential modulatory effects of stimulus concreteness on the expression of such complex productive behavior.

The clinical profile of cerebral small vessel disease: Toward an evidence-based identification of cognitive markers

There is no consensus on which test is more suited to outline the cognitive deficits of cerebral small vessel disease (cSVD) patients. We explored the ability of eight cognitive tests, selected in a previous systematic review as the most commonly used in this population, to differentiate among cSVD patients, controls, and other dementing conditions performing a meta-analysis of 86 studies. We found that cSVD patients performed worse than healthy controls in all tests while data on the comparison to neurodegenerative diseases were limited. We outlined a lack of data on these tests' accuracy on the diagnosis. Cognitive tests measuring processing speed were those mostly associated with neuroimaging cSVD markers. There is currently incomplete evidence that a single test could differentiate cSVD patients with cognitive decline from other dementing diseases. We make preliminary proposals on possible strategies to gain information about the clinical definition of cSVD that currently remains a neuroimaging-based one.

The Boston Process Approach and Digital Neuropsychological Assessment: Past Research and Future Directions

Neuropsychological assessment using the Boston Process Approach (BPA) suggests that an analysis of the strategy or the process by which tasks and neuropsychological tests are completed, and the errors made during test completion convey much information regarding underlying brain and cognition and are as important as overall summary scores. Research over the last several decades employing an analysis of process and errors has been able to dissociate between dementia patients diagnosed with Alzheimer's disease, vascular dementia associated with MRI-determined white matter alterations, and Parkinson's disease; and between mild cognitive impairment subtypes. Nonetheless, BPA methods can be labor intensive to deploy. However, the recent availability of digital platforms for neuropsychological test administration and scoring now enables reliable, rapid, and objective data collection. Further, digital technology can quantify highly nuanced data previously unobtainable to define neurocognitive constructs with high accuracy. In this paper, a brief review of the BPA is provided. Studies that demonstrate how digital technology translates BPA into specific neurocognitive constructs using the Clock Drawing Test, Backward Digit Span Test, and a Digital Pointing Span Test are described. Implications for using data driven artificial intelligence-supported analytic approaches enabling the creation of more sensitive and specific detection/diagnostic algorithms for putative neurodegenerative illness are also discussed.

Alzheimer's/Vascular Spectrum Dementia: Classification in Addition to Diagnosis

Alzheimer's disease (AD) and vascular dementia (VaD) are the two most common types of dementia. Although the combination of these disorders, called 'mixed' dementia, is recognized, the prevailing clinical and research perspective continues to consider AD and VaD as independent disorders. A review of recent neuropathological and neuropsychological literature reveals that these two disorders frequently co-occur and so-called 'pure' AD or VaD is comparatively rare. In addition, recent research shows that vascular dysfunction not only potentiates AD pathology, but that pathological changes in AD may subsequently induce vascular disorders. On the basis of these data, we propose that the neurobiological underpinnings underlying AD/VaD dementia and their neuropsychological phenotypes are best understood as existing along a clinical/pathological continuum or spectrum. We further propose that in conjunction with current diagnostic criteria, statistical modeling techniques using neuropsychological test performance should be leveraged to construct a system to classify AD/VaD spectrum dementia in order to test hypotheses regarding how mechanisms related to AD and VaD pathology interact and influence each other.

Perseverative Behavior on Verbal Fluency Task in Patients with Huntington's Disease: a Retrospective Study on a Large Patient Sample

OBJECTIVE

Patients with Huntington's disease (HD) may show impairments of frontal cortical-subcortical circuits with difficulties on cognitive flexibility tasks. One marker of poor flexibility is "perseveration" behavior, which refers to inappropriate and involuntary production of iterative responses not adequate to the current task demands. This study explored frequency, type, and possible cognitive mechanisms of verbal perseverations in a large sample of HD patients.

METHOD

A sample of 128 patients with HD underwent phonological and category verbal fluency tests to assess perseverative errors, within a wide neuropsychological, psychopathological, motor, and functional assessment.

RESULTS

Perseverative errors in verbal fluency task occurred in 89 (69.5%) patients. Patients showing perseverations scored significantly lower than patients without perseverations on tasks tapping executive and motor functions and on functional independence scales. Logistic regression analysis revealed a significant independent association of verbal perseverations with scores on Trail Making Test only. Conclusions: Verbal perseverations are frequent in HD patients and are likely related with impairments of attentional switching and working memory, hampering tracking of verbal responses already produced. Perseverative behavior may serve as a useful clinical marker of cognitive and functional impairment in patients with HD.

Common neurodegenerative disorders in the perioperative setting: Recommendations for screening from the Society for Perioperative Assessment and Quality Improvement (SPAQI)

Aging is associated with normal and abnormal brain and cognitive changes. Due to the expected increase in older adults requiring surgery, perioperative clinicians will be increasingly encountering patients with neurodegenerative disease. To help perioperative clinicians understand signs of abnormal behaviors that may mark an undiagnosed neurodegenerative disorder and alert additional patient monitoring, The Society for Perioperative Assessment and Quality Improvement (SPAQI) worked with experts in dementia, neuropsychology, geriatric medicine, neurology, and anesthesiology to provide a summary of cognitive and behavioral considerations for patients with common neurodegenerative disorders being evaluated at preoperative centers. Patients with neurodegenerative disorders are at high risk for delirium due to known neurochemical disruptions, medication interactions, associated frailty, or vascular risk profiles presenting risk for repeat strokes. We provide basic information on the expected cognitive changes with aging, most common neurodegenerative disorders, a list of behavioral features and considerations to help differentiate neurodegenerative disorders. Finally, we propose screening recommendations intended for a multidisciplinary team in the perioperative setting.

The oblique effect: The relationship between profiles of visuospatial preference, cognition, and brain connectomics in older adults

The oblique effect (OE) describes the visuospatial advantage for identifying stimuli oriented horizontally or vertically rather than diagonally; little is known about brain aging and the OE. We investigated this relationship using the Judgment of Line Orientation (JLO) in 107 older adults (∼age = 67.8 ± 6.6; 51% female) together with neuropsychological tests of executive functioning (EF), attention/information processing (AIP), and neuroimaging. Only JLO lines falling between 36-54° or 126-144° were considered oblique. To quantify the oblique effect, we calculated z-scores for oblique errors (zOblique = #oblique errors/#oblique lines), and similarly, horizontal + vertical line errors (zHV), and a composite measure of oblique relative to HV errors (zOE). Composite z-scores of EF and AIP reflected domains associated with JLO performance. Graph theory analysis integrated T1-derived volumetry and diffusion MRI-derived white matter tractography into connectivity matrices analyzed for select network properties. Participants produced more zOblique than zHV errors (p < 0.001). Age was not associated with zOE adjusting for sex, education, and MMSE. Similarly adjusted linear regression models revealed that lower EF was associated with a larger oblique effect (p < 0.001). Modular analyses of neural connectivity revealed a differential patterns of network affiliation that varied by high versus low group status determined via median split of zOblique and zHV errors, separately. Older adults exhibit the oblique effect and it is associated with specific cognitive processes and regional brain networks that may facilitate future investigations of visuospatial preference in aging.

Drawing Disorders in Alzheimer's Disease and Other Forms of Dementia

Drawing is a multicomponential process that can be impaired by many kinds of brain lesions. Drawing disorders are very common in Alzheimer's disease and other forms of dementia, and can provide clinical information for the distinction of the different dementing diseases. In our review we started from an overview of the neural and cognitive bases of drawing, and from a recollection of the drawing tasks more frequently used for assessing individuals with dementia. Then, we analyzed drawing disorders in dementia, paying special attention to those observed in Alzheimer's disease, from the prodromal stages of the amnesic mild cognitive impairment to the stages of full-blown dementia, both in the sporadic forms with late onset in the entorhino-hippocampal structures and in those with early onset in the posterior neocortical structures. We reviewed the drawing features that could differentiate Alzheimer's disease from vascular dementia and from the most frequent forms of degenerative dementia, namely frontotemporal dementia and Lewy body disease. Finally, we examined some peculiar aspects of drawing disorders in dementia, such as perseverations, rotations, and closing-in. We argue that a careful analysis of drawing errors helps to differentiate the different forms of dementia more than overall accuracy in drawing.

A Patient With Bipolar Illness and Her Neuropsychological Signature

This article describes a case study in which neuropsychological assessment was carried out on a 30-year-old, previously diagnosed, bipolar female to determine existence of specific deficits in cognitive function. The patient, whose mood cycles were 12 hours to 24 hours, was subsequently evaluated 8 hours per day for 5 consecutive days (a complete work week of neuropsychological assessment). Neuropsychological results showed motor slowing, right hemispheric dysfunctioning, and memory problems during depressive periods and attentional and executive problems during hypomanic and manic periods. The most normal performance was found during euthymic periods. In addition, left and right hemi visual neglect, aphasia, and sensorimotor problems were present across all mood states. Treatment implications are subsequently described.

The Genesis of Graphic Perseverations in Alzheimer's Disease and Vascular Dementia

OBJECTIVE

Perseveration is the involuntary production of iterative responses. This study explored graphic perseverative errors in Alzheimer's disease and vascular dementia, to comprehend the neuropsychological correlates of this behavior.

METHOD

We performed a retrospective analysis of graphic productions in 114 individuals with clinical diagnosis of Alzheimer's disease and in 63 individuals with clinical diagnosis of vascular dementia, who completed frontal-executive, visuo-spatial, visuo-constructional, and verbal memory tests. For assessing perseverative behavior, we considered recurrent perseverations (inappropriate re-drawing of a figure drawn in a previous trial) and continuous perseverations (inappropriate replication of the same figure or of its element within one trial) produced in a standard copying task.

RESULTS

Two or more graphic perseverative errors occurred in 66/114 individuals with Alzheimer's disease (57.9%) and in 31/63 individuals with vascular dementia (49.2%). Participants with moderate-to-severe dementia produced a significantly higher number of perseverations than individuals with mild dementia. Logistic regression revealed a significant relationship of graphic perseverations with frontal and visuo-constructive impairments, in both Alzheimer's disease and vascular dementia.

CONCLUSIONS

Graphic perseverations are frequent in both Alzheimer's disease and vascular dementia. Frontal-executive defects can hamper inhibition of iterative graphic productions. Identification of graphic perseverations can be useful for detection and monitoring of frontal-executive impairments throughout the disease course in individuals with dementia.

Untimed Design Fluency in Aging and Alzheimer's Disease: Psychometrics and Normative Data

Design fluency tests, commonly used in both clinical and research contexts to evaluate nonverbal concept generation, have the potential to offer useful information in the differentiation of healthy versus pathological aging. Although normative data for older adults (OAs) are available for multiple timed versions of this test, similar data have been unavailable for a previously published untimed test, the Graphic Pattern Generation Test (GPG). Time constraints common to almost all of the available design fluency tests may cloud interpretation of higher-level executive abilities-for example, in individuals with slow processing speed. The current study examined the psychometric properties of the GPG and presents normative data in a sample of 167 healthy OAs and 110 individuals diagnosed with Alzheimer's disease (AD). Results suggest that a brief version of the GPG can be administered reliably and that this short form has high test-retest and interrater reliability. Number of perseverations was higher in individuals with AD as compared with OAs. A cutoff score of 4 or more perseverations showed a moderate degree of sensitivity (76%) and specificity (37%) in distinguishing individuals with AD and OAs. Finally, perseverations were associated with nonmemory indexes, thereby underscoring the nonverbal nature of this error in OAs and individuals with AD.

Analysis of verbal fluency ability in Alzheimer's disease: the role of clustering, switching and semantic proximities

The underlying nature of verbal fluency deficits in Alzheimer's disease (AD) was investigated in this study. Participants were 48 individuals with AD and 48 cognitively healthy older adults. Fluency performance on letter and category tasks was analyzed across two 30-s intervals for total words produced, mean cluster size, and total switches. Compared with the control group, AD participants produced fewer words and switches on both fluency tasks and had a reduced category cluster size. The AD group was differentially impaired on category compared with letter fluency and produced more repetitive responses but fewer category exemplars than controls on the category task. A multidimensional scaling approach revealed that AD participants' semantic maps were similar to controls. Overall, the data suggest that executive abilities involving search and retrieval processes and a reduced availability of semantically related words contributed to the AD group's poorer performance despite similar temporal recall and organizational patterns.

Edith Kaplan and the Boston Process Approach

The history including some of the intellectual origins of the Boston Process Approach and some misconceptions about the Boston Process Approach are reviewed. The influence of Gestalt psychology and Edith Kaplan's principal collaborators regarding the development of the Boston Process Approach is discussed.

Neuropsychological and neuroimaging markers in early versus late-onset Alzheimer's disease

BACKGROUND

Early-onset Alzheimer's disease (EOAD) has been overshadowed by the more common late-onset AD (LOAD). Yet, the literature indicates EOAD may have less hippocampal-memory presentations and more focal neocortical localization early in the disease.

OBJECTIVE

To evaluate these proposed differences between these 2 forms of AD and to explore what they inform about differences in AD pathophysiology.

METHODS

In all, 21 patients with EOAD and 24 patients with LOAD matched for disease progression and severity were compared on neurocognitive measures and resting state fluorodeoxy-glucose positron-emission tomography (FDG-PET).

RESULTS

Patients with EOAD had worse executive functions with greater hypometabolism in the parietal regions; whereas patients with LOAD had worse confrontation naming and verbal recognition memory with greater hypometabolism in inferior frontotemporal regions.

CONCLUSIONS

In addition to highlighting significant differences between EOAD and LOAD, these results reveal dissociation between executive deficits in AD and frontal hypometabolism, suggesting early disturbances of the parietal-frontal network in EOAD.

The frontal-anatomic specificity of design fluency repetitions and their diagnostic relevance for behavioral variant frontotemporal dementia

On tests of design fluency, an examinee draws as many different designs as possible in a specified time limit while avoiding repetition. The neuroanatomical substrates and diagnostic group differences of design fluency repetition errors and total correct scores were examined in 110 individuals diagnosed with dementia, 53 with mild cognitive impairment (MCI), and 37 neurologically healthy controls. The errors correlated significantly with volumes in the right and left orbitofrontal cortex (OFC), the right and left superior frontal gyrus, the right inferior frontal gyrus, and the right striatum, but did not correlate with volumes in any parietal or temporal lobe regions. Regression analyses indicated that the lateral OFC may be particularly crucial for preventing these errors, even after excluding patients with behavioral variant frontotemporal dementia (bvFTD) from the analysis. Total correct correlated more diffusely with volumes in the right and left frontal and parietal cortex, the right temporal cortex, and the right striatum and thalamus. Patients diagnosed with bvFTD made significantly more repetition errors than patients diagnosed with MCI, Alzheimer's disease, semantic dementia, progressive supranuclear palsy, or corticobasal syndrome. In contrast, total correct design scores did not differentiate the dementia patients. These results highlight the frontal-anatomic specificity of design fluency repetitions. In addition, the results indicate that the propensity to make these errors supports the diagnosis of bvFTD. (JINS, 2012, 18, 1-11).

Cerebrovascular disease and cognition in older adults

The well-established association between advanced age, cerebrovascular pathology, and cognitive decline is receiving greater attention as the population attains new levels of longevity. This chapter will provide an overview of vascular anatomy and age-related cerebrovascular disorders and diseases, including stroke and degenerative dementia. The cognitive and functional sequellae of these cerebrovascular disorders will also be described in detail. Throughout this review, we will emphasize topics that have been relatively underrepresented in the literature, including age-related diseases of the cerebral small vessels, nuanced characterization of cognitive impairment associated with insidious small-vessel vascular dementia, and the real-life functional consequences of cerebrovascular changes in older adults.

Dysexecutive functioning in mild cognitive impairment: derailment in temporal gradients

Libon et al. (2010) provided evidence for three statistically determined clusters of patients with mild cognitive impairment (MCI): amnesic (aMCI), dysexecutive (dMCI), and mixed (mxMCI). The current study further examined dysexecutive impairment in MCI using the framework of Fuster's (1997) derailed temporal gradients, that is, declining performance on executive tests over time or test epoch. Temporal gradients were operationally defined by calculating the slope of aggregate letter fluency output across 15-s epochs and accuracy indices for initial, middle, and latter triads from the Wechsler Memory Scale-Mental Control subtest (Boston Revision). For letter fluency, slope was steeper for dMCI compared to aMCI and NC groups. Between-group Mental Control analyses for triad 1 revealed worse dMCI performance than NC participants. On triad 2, dMCI scored lower than aMCI and NCs; on triad 3, mxMCI performed worse versus NCs. Within-group Mental Control analyses yielded equal performance across all triads for aMCI and NC participants. mxMCI scored lower on triad 1 compared to triads 2 and 3. dMCI participants also performed worse on triad 1 compared to triads 2 and 3, but scored higher on triad 3 versus triad 2. These data suggest impaired temporal gradients may provide a useful heuristic for understanding dysexecutive impairment in MCI.

Auditory responsive naming versus visual confrontation naming in dementia

Dysnomia is typically assessed during neuropsychological evaluation through visual confrontation naming. Responsive naming to description, however, has been shown to have a more distributed representation in both fMRI and cortical stimulation studies. While naming deficits are common in dementia, the relative sensitivity of visual confrontation versus auditory responsive naming has not been directly investigated. The current study compared visual confrontation naming and auditory responsive naming in a dementia sample of mixed etiologies to examine patterns of performance across these naming tasks. A total of 50 patients with dementia of various etiologies were administered visual confrontation naming and auditory responsive naming tasks using stimuli that were matched in overall word frequency. Patients performed significantly worse on auditory responsive naming than visual confrontation naming. Additionally, patients with mixed Alzheimer's disease/vascular dementia performed more poorly on auditory responsive naming than did patients with probable Alzheimer's disease, although no group differences were seen on the visual confrontation naming task. Auditory responsive naming correlated with a larger number of neuropsychological tests of executive function than did visual confrontation naming. Auditory responsive naming appears to be more sensitive to effects of increased of lesion burden compared to visual confrontation naming. We believe that this reflects more widespread topographical distribution of auditory naming sites within the temporal lobe, but may also reflect the contributions of working memory and cognitive flexibility to performance.

Neuropsychological assessment of dementia

Neuropsychological studies show that cognitive deficits associated with Alzheimer's disease (AD) are distinct from age-associated cognitive decline. Quantitative and qualitative differences are apparent across many cognitive domains, but are especially obvious in episodic memory (particularly delayed recall), semantic knowledge, and some aspects of executive functions. The qualitatively distinct pattern of deficits is less salient in very old AD patients than in younger AD patients. Although decline in episodic memory is usually the earliest cognitive change that occurs prior to the development of the AD dementia syndrome, asymmetry in cognitive abilities may also occur in this "preclinical" phase of the disease and predict imminent dementia. Discrete patterns of cognitive deficits occur in AD and several neuropathologically distinct age-associated neurodegenerative disorders. Knowledge of these differences helps to clinically distinguish among various causes of dementia and provides useful models for understanding brain-behavior relationships that mediate cognitive abilities affected in various neurodegenerative diseases.

Perseveration in Alzheimer's disease

BACKGROUND/AIMS AND METHODS

Perseveration is common in Alzheimer's disease (AD). We document the type and quantitative burden of perseveration as cognitive decline progresses from normal aging (n = 30) through mild AD (n = 20) to moderate AD (n = 20) by administering a semantic verbal fluency task.

RESULTS

We found perseveration to increase significantly with increasing severity of AD and different types of perseveration that distinguish the subject groups in a statistically significant manner. Recurrent and continuous perseverations appear early in AD. As the disease progresses in severity into moderate stage, the number of recurrent and continuous perseverations increases, and stuck-in-set perseverations emerge.

CONCLUSION

The different types of perseveration are likely to reflect the progressive deterioration of different brain regions in AD.

Evaluating the role of motor regulation in figural fluency: partialing variance in the Ruff Figural fluency test

Figural fluency is often thought to assess the ability to "think fluently and flexibly in the visual-spatial mode" (Ruff, 1988). However, the contribution of motor regulation to the performance of this task has not been previously examined. The goal of this study was to evaluate the potential relationship between motor sequence fluency (without a visual-spatial component) and figural fluency. A total of 55 participants (ages 18 to 68 years) were administered (a) the Ruff Figural Fluency Task (RFFT), (b) the Trail Making Test Part B (TMT-B), which overlaps with the RFFT in visual tracking and graphomotor demands, (c) an electronically administered Motor Sequence Fluency Test (MSFT), which overlaps with the RFFT in generation of novel hand movements in the absence of visual stimuli, and (d) a Complex Motor Programming Task. Hierarchical regression analyses were used to determine whether complex motor programming uniquely contributes to RFFT performance above and beyond the processes that are traditionally assumed to be required, as well as to determine whether the ability to generate novel motor sequences uniquely contributes to RFFT performance. Age and education were also added to the regression models in order to determine the contribution of demographic variables to the current findings. Results indicated that age, specific components of motor programming, and nonvisual motor generative fluency represent the most prominent predictors of RFFT performance. Consequently, the role of motor regulation and motor flexibility may in fact be more important for RFFT performance than previously thought, whereas visual-spatial processing may play a lesser role.

Cognitive-behavioral profiles of neurodegenerative dementias: beyond Alzheimer's disease

The neurocognitive and behavioral profiles of vascular dementia and vascular cognitive impairment, dementia with Lewy bodies and Parkinson's disease with dementia, and dementia syndromes associated with frontotemporal lobar degenerations are compared and contrasted with Alzheimer's dementia (AD). Vascular dementia/vascular cognitive impairment is characterized by better verbal memory performance, worse quantitative executive functioning, and prominent depressed mood. Dementia with Lewy bodies and Parkinson's disease with dementia are equally contrasted with AD by defective processing of visual information, better performance on executively supported verbal learning tasks, greater attentional variability, poorer qualitative executive functioning, and the presence of mood-congruent visual hallucinations. The frontal variant of frontotemporal lobar degeneration (frontotemporal dementia) differs from AD by better multimodal retention on learning tasks, different patterns of generative word fluency, defective qualitative executive functioning, and by markedly impairment of comportment. For temporal variants of frontotemporal lobar degenerations, progressive aphasia and semantic dementia, worse language performance relative to AD is typically characteristic.

Profiles of neuropsychological impairment in autopsy-defined Alzheimer's disease and cerebrovascular disease

Differentiating the cognitive effects of cerebrovascular disease, particularly small vessel disease, from those of Alzheimer's disease is a difficult clinical challenge. An influential model of how subcortical cerebrovascular disease causes cognitive dysfunction posits that damage to frontostriatal loops impairs frontal lobe function, leading to predominant impairment of executive function and secondary impairments of associated cognitive functions such as memory. Consistent with this, neuropsychological studies of clinically diagnosed patients have reported that individuals with vascular dementia do better on memory tests and worse on executive function tests compared with patients with Alzheimer's disease. This observation has led to the suggestion that predominant cognitive executive dysfunction might serve as a useful diagnostic marker for vascular dementia. We sought to test this idea in a series of cases with autopsy-defined pathologies. Subjects were 62 autopsied cases from a prospective study of vascular contributions to dementia. Using neuropathological features alone, 23 were diagnosed with Alzheimer's disease (AD), 11 with cerebrovascular disease (CVD), 9 with both (mixed pathology) and 19 with normal elderly brain (NEB). Three psychometrically matched composite scales of different cognitive abilities were used: Verbal Memory, Nonverbal Memory and Executive Function. Analysis of group data showed that for Alzheimer's disease memory scores were lower than Executive Function by nearly a standard deviation on average. In contrast, and contrary to the model, CVD was rather equally impaired on Executive Function, Verbal Memory and Nonverbal Memory. Individual patterns of cognitive impairment were examined by defining three profiles based on reliable differences between neuropsychological scores to characterize cases with predominant memory impairment, predominant executive dysfunction, and 'other' patterns. Analysis of individual impairment profiles showed that predominant memory impairment was present in 71% of Alzheimer's disease while predominant executive dysfunction described only 45% of CVD. A stronger pattern emerged when cognitively normal cases were excluded; among the six cognitively impaired CVD patients four had predominant executive dysfunction and none had predominant memory impairment. This report, comprised of a substantial sample of autopsy confirmed cases, delineates the patterns of neuropsychological impairment associated with small vessel cerebrovascular disease and Alzheimer's disease While the findings show that memory loss usually exceeds executive dysfunction in patients with Alzheimer's disease, the reverse is not the case in CVD. Taken as a whole, the results indicate that the cognitive effects of the small vessel cerebrovascular disease are variable and not especially distinct, thus raising question about the utility of executive impairment as a diagnostic marker for vascular dementia.

Alterations in working memory as a function of leukoaraiosis in dementia

Dementia research suggests executive dysfunction is best understood within the context of disease-specific neuropathology. Leukoaraiosis (LA) results in executive dysfunction yet little is known about its impact on specific aspects of working memory (WM). This study aimed to investigate the relationship between MRI LA severity and WM in dementia. A visual rating scale was used to assign patients with dementia into groups with minimal-mild LA (Low LA; n=34) and moderate-severe LA (High LA; n=32). A modified Digit Span Backward Task consisting of 3-, 4-, and 5-span trials measured specific components of WM. Short-term storage and rehearsal in WM were assessed by the total number of digits reported regardless of recall order (ANY-ORDER; e.g., 47981 recalled '18943', score=4). Mental manipulation in the form of disengagement and temporal re-ordering was assessed by the total number of digits recalled in correct position (SERIAL-ORDER; e.g., 47981 recalled '18943', score=3). There was no difference between LA groups on ANY-ORDER comparisons. The High LA group obtained lower SERIAL-ORDER scores than the Low LA group. Stepwise regression analyses were conducted that first entered MMSE scores then composite z-scores reflecting executive functioning, language and memory. ANY-ORDER performance variance was explained solely by dementia severity. SERIAL-ORDER performance variance was further explained by executive dysfunction. Results suggest that high degrees of LA do not interfere with immediate (digit) recall but do interfere with disengagement and temporal re-ordering. LA may disconnect the frontal lobes from subcortical and cortical structures that form the neuronal networks critical for these WM functions.

Selective lesions of the nucleus basalis magnocellularis impair cognitive flexibility

The authors tested the hypothesis that the cholinergic nucleus basalis magnocellularis (NBM) is involved in solving problems requiring cognitive flexibility. Rats with 192 IgG-saporin lesions of the NBM were assessed for perseveration (i.e., cognitive inflexibility) in the serial reversal of an operant discrimination and during subsequent extinction testing. It was hypothesized that the NBM lesion and control groups would not differ in the acquisition of the initial, simple discrimination, because this task does not demand cognitive flexibility. In contrast, it was hypothesized that the NBM lesion group would show perseveration during serial reversal and extinction testing. Results generally supported these hypotheses, suggesting that the NBM plays an important role in mediating cognitive flexibility.

Everyday action in dementia: evidence for differential deficits in Alzheimer's disease versus subcortical vascular dementia

The relationship between dementia diagnosis and everyday action (e.g., meal preparation, grooming) is not well understood. This study examines differences between individuals diagnosed with vascular dementia (VaD; n = 25) versus Alzheimer's disease (AD; n = 23) on the Naturalistic Action Test (NAT; Schwartz et al., 2003), a performance-based measure that includes three tasks of increasing complexity. The percentage of task steps accomplished, number of errors, and performance times were recorded for each task. While the groups did not differ in dementia severity or overall impairment on the NAT, the VaD group committed more errors (3.3 vs. 1.6, p = 02). The VaD group also accomplished significantly fewer steps when salient distractor objects were present (74.0% vs. 91.3%, p < .01). Correlations between NAT variables and neuropsychological tests suggest the executive control deficits associated with VaD may contribute to specific action difficulties, such as distractor interference and inefficient, error-prone action on complex tasks. In AD, everyday action may be negatively influenced by episodic memory failures. Thus, dementia diagnosis has relevance to everyday function.

Patterns of memory impairment and perseverative behavior discriminate early Alzheimer's disease from subcortical vascular dementia

Previous research suggests that the neuropsychological deficits in Alzheimer's disease (AD) are different from that of vascular dementia (VaD), especially with respect to memory, language and executive functions, but negative findings were reported. Our objective was to clarify the cognitive syndrome in AD and VaD in the early stage of these disorders. We investigated 45 patients with early AD, 23 patients with subcortical VaD and 35 normal controls. All subjects were assessed with neuropsychological battery designed to measure memory, language, praxis and executive functions. Patients with AD had significantly worse scores on Story Recall (p<0.02) and on all measures of the Free and Cued Selective Reminding Test (p<0.03 to 0.001) than did patients with VaD, as well as greater number of perseverations (p<0.02) on category fluency. Conversely, VaD patients had more perseverations (p<0.02) on the Modified Card Sorting Test. Despite the similar degree of overall cognitive deterioration, the findings show more impaired retrieval from long-term storage in AD than in VaD. Moreover, the data suggest that AD and subcortical VaD affect perseverative behavior in a different fashion. These results may be helpful in differentiating AD from VaD in the early stage of these disorders, when mental impairments are not pervasive yet.

Screening of dementia in stroke patients with lacunar infarcts: comparison of the mattis dementia rating scale and the mini-mental state examination

There have been no data on the performance of the Initiation-Perseveration subtest of the Mattis Dementia Rating Scale (MDRS-IP) in screening poststroke dementia (PSDE). Three months after the index stroke, a research assistant administered the MDRS-IP and Mini-Mental State Examination (MMSE) to 83 Chinese stroke patients with lacunar infarcts who were consecutively admitted to the stroke unit of a general hospital. A psychiatrist, who was blind to the MDRS-IP and MMSE scores, interviewed all 83 patients and made a Diagnostic and Statistical Manual of Mental Disorders (4th edition) diagnosis of dementia, which served as the benchmark for judging the performance of MDRSIP. The optimal cutoff point of MDRS-IP was 22/23. The sensitivity, specificity, and positive and negative predictive values of MDRS-IP, and the area under the receiver operating characteristic curve were 82%, 90%, 0.41, 0.98, and 0.91, respectively. The overall performance of the MDRS-IP was comparable to the MMSE.

Clock drawing errors in dementia: neuropsychological and neuroanatomical considerations

OBJECTIVES

A clock drawing test scoring system is presented to explore the neuropsychological/neuroanatomic components underlying clock drawing in patients initially diagnosed with Alzheimer disease, ischemic vascular dementia associated with white matter alterations, and Parkinson disease.

METHODS

Fourteen clock drawing test errors were scored to create 4 clock drawing test subscales that assess different underlying cognitive operations.

RESULTS

In the command condition, errors on the Time subscale were correlated with impairment on executive control measures. In the copy condition, errors on the Perseveration/Pull to Stimulus subscale was also correlated with executive control measures. Patients presenting with mild (low) magnetic resonance imaging white matter alterations, significant (high) white matter alterations, and Parkinson disease were compared. In the command condition, the low white matter alterations group made fewer total errors than the Parkinson disease group. In the copy condition, the low white matter alterations group made fewer errors on the Time, Spatial Layout, and Perseveration/Pull to Stimulus clock drawing test subscales than the high white matter alterations or Parkinson disease groups. Few differences were noted between the high white matter alterations and Parkinson disease groups.

DISCUSSION

Our data suggest that heavy demands on executive control associated with the interruption of large-scale cortical-subcortical neural networks underlie impairment in clock drawing in mild dementia.

Pre-frontal executive committee for perception, working memory, attention, long-term memory, motor control, and thinking: a tutorial review

As an explicit organizing metaphor, memory aid, and conceptual framework, the prefrontal cortex may be viewed as a five-member 'Executive Committee,' as the prefrontal-control extensions of five sub-and-posterior-cortical systems: (1) the 'Perceiver' (dominant-right-hemisphere ventral-lateral prefrontal cortex--VL/PERC-PFC) is the frontal extension of the ventral perceptual stream (the VL/PERC system) which represents the world and self in object coordinates; (2) the 'Verbalizer' (dominant-left-hemisphere ventral-lateral prefrontal cortex system--VL/VERB-PFC) is the frontal extension of the language stream (the VL/VERB system) which represents the world and self in language coordinates; (3) the 'Motivator' (ventral/medial-orbital pre-frontal cortex--VMO-PFC) is the frontal cortical extension of a subcortical extended-amygdala stream (the VMO system) which represents the world and self in motivational/emotional coordinates; (4) the 'Attender' (dorsal-medial/anterior cingulate--DM/AC-PFC) is the frontal cortical extension of a subcortical extended-hippocampal stream (the DM/AC system) which represents the world and self in spatiotemporal coordinates and directs attention to internal and external events; and (5) the 'Coordinator' (the dorsolateral prefrontal cortex--DL-PFC) is the frontal extension of the dorsal perceptual stream (the DL system) which represents the world and self in body- and eye-coordinates and controls willed action and working memory. This tutorial review examines the interacting roles of these five systems in perception, working memory, attention, long-term memory, motor control, and thinking.

Naturalistic action impairments in dementia

Naturalistic actions are everyday tasks (e.g. cooking) that require one to use multiple objects and sequence steps to achieve a goal. Naturalistic action impairment has been attributed to executive dysfunction [Higher cortical functions in man. New York: Basic Books, 1966], semantic knowledge degradation [Brain 111 (1988) 1173], and, more recently, general limitations in cognitive resources [Neuropsychology 12 (1998) 13]. Action impairments were explored in 51 dementia participants with the short form of the multi-level action test (MLAT-S). A clinical neuropsychological test protocol was also administered. Regression analyses including measures of executive functioning, semantic knowledge, and global cognitive functioning showed that global cognitive functioning was the best predictor of MLAT-S errors. Furthermore, task demands significantly influenced the type and frequency of errors, and dementia participants showed a pattern of errors similar to that reported in other clinical populations [Cognitive Neuropsychology 15 (1998) 617; Neuropsychologia 37 (1999) 51; Neuropsychology 12 (1998) 13]. Taken together, the present findings are inconsistent with semantic and executive accounts, but support the limited-capacity resource theory of naturalistic action impairment.

Mixed dementia: epidemiology, diagnosis, and treatment

Alzheimer's disease (AD) and vascular dementia (VaD) are the most frequent causes of dementia in older people. Although AD can be diagnosed with a considerable degree of accuracy, the distinction between isolated AD, VaD, and mixed dementia (MD), where both pathologies coexist in the same patient, remains a controversial issue and one of the most difficult diagnostic challenges. Although MD represents a very frequent pathology, especially in older people, as reported in neuropathological studies, the respective importance of degenerative and vascular lesions, their interaction in the genesis of dementia, and the mere existence of MD are still debated. Accurate diagnosis of MD is of crucial significance for epidemiological purposes and for preventive and therapeutic strategies. Until recently, pharmacological studies have generally focused on pure disease, AD or VaD, and have provided little information on the best therapeutic approach to MD. This article provides an overview of MD in older people. A retrospective review of the recent literature on prevalence, incidence, course, risk factors, diagnosis, and treatment of MD was performed. The article also emphasizes the need for further studies, including neuropsychological and functional evaluations, and neuroimaging and clinicopathological correlations to develop a better understanding of MD, which appears to be one of the most common forms of dementia.

Can clock drawing test help to differentiate between dementia of the Alzheimer's type and vascular dementia? A preliminary study

OBJECTIVES

the purpose of this preliminary study was to determine if clock drawing performance may help to differentiate between dementia of the Alzheimer's type (DAT) and vascular dementia (VD) patients.

METHODS

eighty-eight community-dwelling outpatients were comprehensively evaluated and met DSM-IV criteria for DAT or VD. Cognitive evaluation included the Mini-Mental State Examination (MMSE) and the Cambridge Cognitive Examination (CAMCOG). CAMCOG derived clock drawings were blindly evaluated by the same investigator, according to Freedman's method for clock drawing, and a total score as well as subscores (contour, numbers, hands and center) were determined.

RESULTS

There were no significant differences between DAT and VD patients in terms of demographic (age, gender, education) and cognitive (MMSE score, CAMCOG score) characteristics. On the average, the VD group showed slightly poorer performance on each of the clock drawing test (CDT) measures studied. With application of the Bonferroni correction, only Freedman's total score and hands subscore were statistically different between groups (p<0.003, p<0.004, respectively). Stepwise logistic regression analyses showed that the only significant variable was Freedman's total score (B=-0.273, p=0.005). Stepwise discriminant analysis identified Freedman's total score as the only significant predictor of diagnosis (Wilkes' lambda=0.903, p=0.003). This model correctly classified 65.9% overall into the respective DAT and VD groups.

CONCLUSIONS

CDT scored according to a comprehensive technique may be of value in differentiating DAT from VD patients. We hypothesize that the classificatory ability of Freedman's method might be attributed to its presumed sensitivity to impaired executive functioning which is more pronounced in VD compared with DAT patients.

Neuropsychological deficit in early subcortical vascular dementia: comparison to Alzheimer's disease

To further clarify the cognitive syndrome in subcortical vascular dementia (VaD), we investigated 20 patients with early-stage VaD as compared with 30 patients with Alzheimer's disease (AD) and 22 normal controls using episodic memory, attention/executive function and language tests. The patient groups were closely matched in terms of age, education and severity of dementia. The VaD patients had a significantly better free recall, cued recall and recognition memory than AD patients, the recognition being within normal limits in VaD. In addition, VaD patients had a greater number of perseverative errors during the Modified Card Sorting test, while AD patients exhibited more perseverations of semantic fluency. The results of retrieval deficit syndrome and increased number of perseverations during tasks sensitive to frontal lobe function are in agreement with the studies emphasizing the importance of frontal dysfunction in subcortical VaD. These findings are relevant for the early diagnosis of VaD and might be useful in the differential diagnosis with AD.

Frontal impairment in subcortical ischemic vascular dementia in comparison to Alzheimer's disease

We compared the performance of patients with Alzheimer's disease to that of patients with subcortical vascular dementia (s-IVD) in a set of tasks assessing categorization abilities, sustained and selective attention, and set-shifting and set-maintaining skills. Only the measures of naming and categorization abilities on the Test of Classification and Recall of Pictures (TCRP) proved useful in differentiating AD from s-IVD patients. s-IVD patients showed worse performance than AD on the TCRP categorization measures, while both AD and s-IVD patients were equally impaired in other tasks assessing executive functions (EF). With respect to the naming task, s-IVD patients made significantly more perseverative and unrelated errors than AD patients. Moreover, in the s-IVD group, we found a strong correlation between categorization ability and an attentional test score (Attentional Matrices), while no such correlation emerged in the AD group. These results suggest a dissociated impairment of EF in the 2 dementia groups. In our view, the lack of inhibition and the inability to manipulate complex information are responsible for a greater executive dysfunction in s-IVD patients in comparison with AD patients. The capacity to build up strategies appears more preserved in AD patients, whose impaired performance in executive tasks seems to be related to an impairment of attentional shifting and working memory.

Contribution of specific cognitive processes to executive functioning in an aging population

The current study investigated executive function measures emphasizing Alpha Span (ASp) to understand relationships among executive and nonexecutive tasks. Nondemented older participants (N = 417) received a comprehensive cognitive battery. Age and vocabulary adjusted correlations revealed associations among ASp, Wechsler Adult Intelligence Scale--Revised (D. Wechsler, 1981) Digit Span subtests, and fluency tasks. Principal-components analysis with varimax rotation revealed a 4 component solution (86.4% of the variance) with executive variables contributing to all loadings. Calculated component indices were submitted to a regression analysis predicting ASp performance. After accounting for age (6.3% of the variance), Component 3 reflecting brief attention-mental manipulation accounted for 13.4% of ASp variance; Component 1, verbal language ability, 11.5%; Component 2, sustained attention-mental tracking, 1.9%; and Component 4, visuoperceptual spatial organization-planning, 0.9%. Results stress the importance of considering executive and nonexecutive aspects of cognition when conceptualizing executive functioning.

Executive dysfunction in subcortical ischaemic vascular disease

BACKGROUND

Executive dysfunction has been reported in patients with subcortical-frontal pathology, even in the absence of dementia.

OBJECTIVE

This study was undertaken to determine if impairments in executive functioning could be found in non-demented patients with subcortical lacunes.

METHODS

Cross sectional comparison between older control subjects (n=27) and non-demented patients with one or more subcortical lacunes (n=12). All participants were administered a neuropsychological test battery incorporating three measures of executive functioning, the Stroop interference test, California card sorting test, and the initiation-perseveration subtest of the Mattis dementia rating scale.

RESULTS

No group differences were found on measures of recent verbal memory, language, or spatial ability. Normal controls performed better than patients with lacunes in visual memory. On the Stroop interference test, patients with lacunes performed as well as controls on the colour naming condition but slower on the interference condition. Patients with lacunes also generated fewer correct sorts on the California card sort test and achieved lower scores on the initiation-perseveration subtest. Executive measures were correlated with extent of white matter signal hyperintensity but not number of lacunes.

CONCLUSION

Subcortical ischaemic vascular disease is associated with subtle declines in executive functioning and visual memory, even in non-demented patients. The pattern of cognitive impairment after subcortical lacunes is consistent with models of subcortical-frontal circuits.

Differentiation of vascular dementia from AD on neuropsychological tests

BACKGROUND

The concept of vascular dementia (VaD) is currently in a state of evolution. Memory impairment is emphasized as a primary criterion, reflecting the influence of AD on the concept of dementia. We have systematically reviewed whether the nature of neuropsychological dysfunction is distinct in AD and VaD, and whether similar defining criteria for the concept of dementia in both disorders can be supported.

METHODS

We searched five bibliographic databases (Medline, Biological Abstracts, EMBASE, PsychINFO, PsychLIT) for research articles in which VaD and AD had been compared using neuropsychological tests and that met criteria for scientific merit.

RESULTS

Of the 45 studies, 18 were excluded because of inadequacies, and the remaining 27 were analyzed. There were a number of similarities of dysfunction between VaD and AD. However, when matched for age, education, and severity of dementia, VaD patients had relatively superior function in verbal long-term memory and more impairment in frontal executive functioning compared with AD patients. Interpretation of the results is limited by uncertainty in diagnostic criteria for VaD, possible inclusion bias due to use of clinical diagnosis alone, possible overlap of AD and VaD, and the methodologic shortcomings of some studies.

CONCLUSIONS

The neuropsychological differentiation of VaD from AD was consistent with the different neuroimaging findings in the two disorders, and argues for differential criteria for the definition of the syndromes. The simple application of Alzheimer's dementia criteria to VaD, with the inclusion of cerebrovascular disease etiology, may not be sufficient to capture the uniqueness of VaD.

Vascular dementia: a contemporary review of epidemiology, diagnosis, prevention, and treatment

The past decade has seen a renewed interest in vascular dementia. Key epidemiologic studies have examined the prevalence, incidence, course and risk factors of vascular dementia. New classification systems have been developed to improve the reliability of the diagnosis, and there have been advances in diagnostic methodology, such as neuroimaging and neuropsychological assessment. New treatments for vascular dementia are being developed to protect the brain from cerebral ischemia and to limit progression of cognitive impairment. Diagnostic criteria for vascular dementia remain to be validated by carefully designed, systematic, clinicopathologic study. Once such criteria are validated, meaningful study of subgroups of vascular dementia can be explored. Until the relationship between vascular dementia and Alzheimer's disease is better defined, the nosology for vascular dementia may be defined best as dementia associated with stroke.