Utility of a Wisconsin Card Sorting Test short form in persons with Alzheimer's and Parkinson's disease

Characterization of diffusion magnetic resonance imaging revealing relationships between white matter disconnection and behavioral disturbances in mild cognitive impairment: a systematic review

White matter disconnection is the primary cause of cognition and affection abnormality in mild cognitive impairment (MCI). Adequate understanding of behavioral disturbances, such as cognition and affection abnormality in MCI, can help to intervene and slow down the progression of Alzheimer's disease (AD) promptly. Diffusion MRI is a non-invasive and effective technique for studying white matter microstructure. This review searched the relevant papers published from 2010 to 2022. Sixty-nine studies using diffusion MRI for white matter disconnections associated with behavioral disturbances in MCI were screened. Fibers connected to the hippocampus and temporal lobe were associated with cognition decline in MCI. Fibers connected to the thalamus were associated with both cognition and affection abnormality. This review summarized the correspondence between white matter disconnections and behavioral disturbances such as cognition and affection, which provides a theoretical basis for the future diagnosis and treatment of AD.

Long term follow-up in advanced Parkinson's disease treated with DBS of the subthalamic nucleus

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting both motor and non-motor systems. Deep brain stimulation of the subthalamic nucleus (STN-DBS) has been an approved treatment for PD for more than 30 years, but few data are available regarding its long-term effectiveness.

OBJECTIVE

The aim of this study is to evaluate patients' outcome, both from a motor and non-motor perspective, 9 to 14 years after DBS implantation. We have investigated patients with advanced PD and treated with STN-DBS, in relation to key clinical features of PD.

METHODS

18 patients were assessed both retrospectively and prospectively. They underwent motor examination, neuropsychological evaluation and questionnaires on the quality of life, preoperatively, as well as 1, 9 and 14 years after DBS surgery. All patients were implanted with STN-DBS at San Raffaele Hospital between 2004 and 2010.

RESULTS

13 males and five females underwent DBS implantation with a mean PD duration of 11 years. Stimulation significantly improved med-off/stim-on condition up to 9 years, compared to the preoperative off state, and med-on/stim-on condition at 14 years, compared to med-on/stim-off state. Long term improvement specifically involved tremor and rigidity, as well as dopaminergic daily dose. At the same time, STN-DBS had no long-lasting effect on axial symptoms and cognitive functions.

CONCLUSIONS

STN-DBS remains an effective therapy for advanced PD, also over the years. Despite the underlying progression of the disease, this treatment extends the period in which the overall quality of life is still acceptable.

Demographically adjusted normative data for the Wisconsin Card Sorting Test-64 item: Results from the Neuropsychological Norms for the U.S.-Mexico Border Region in Spanish (NP-NUMBRS) project

OBJECTIVE

The Wisconsin Card Sorting Test (WCST) is among the most commonly used tests of executive functioning. We aimed to generate normative data on the 64-item version of this test (WCST-64) for Spanish-speakers living in the U.S.-Mexico Border region.

METHODS

Participants included 189 native Spanish-speakers (Age: 19-60; Education: 0-20; 59.3% female) from the Neuropsychological Norms for the U.S.-Mexico Border Region in Spanish (NP-NUMBRS) project who completed the WCST-64. Univariable and interactive associations between demographic variables and raw scores were examined via Spearman correlations, Wilcoxon Rank-sum tests and linear regressions. T-scores for various WCST-64 measures (Total Errors, Perseverative Responses, Perseverative Errors, Conceptual Level Responses and Number of Categories) were obtained using fractional polynomial equations with weights for age, education, and gender. Percentile scores were reported for Failures to Maintain Set. Rates of impairment (T-score < 40) were calculated by applying the newly developed norms and published norms for non-Hispanic English-speaking Whites and Blacks.

RESULTS

Older age was associated with worse performance and education was linked to better performance on most WCST-64 raw scores, with stronger education effects among females than males. The norms developed here resulted in expected rates of impairment (14-16% across measures). Applying published norms for non-Hispanic Blacks resulted in generally comparable impairment rates. In contrast, applying previously published norms for non-Hispanic Whites overestimated impairment (38-52% across measures).

CONCLUSIONS

These data will enhance interpretation performance on the WCST-64 for Spanish-speakers living in the U.S.-Mexico Border region. Future work will need to examine the generalizability of these norms to other Hispanic/Latino groups.

Impact of prefrontal intermittent theta-burst stimulation on working memory and executive function in Parkinson's disease: A double-blind sham-controlled pilot study

Cognitive impairment is a prevalent non-motor feature of Parkinson's disease (PD) which can present even in early stages of the disease. Impairments in executive processing and working memory (WM) are common and have been attributed, in part, to abnormalities within the dorsolateral prefrontal cortex (DLPFC) and broader fronto-striatal circuitry. Previous studies in cognitively normal adults have suggested intermittent Theta Burst Stimulation (iTBS), an excitatory plasticity-inducing non-invasive brain stimulation technique, can enhance these cognitive functions. Fourteen participants with a diagnosis of idiopathic PD received either Active or Sham iTBS over the left DLPFC across two separate experimental sessions as part of a double-blind sham-controlled crossover experimental design. The Berg's Card Sorting Test (BCST) and N-Back tasks, which measure executive function and WM respectively, were administered prior to iTBS and again five- and 30-minutes following stimulation. Despite being well-tolerated, iTBS failed to modulate performance on any of the cognitive outcome measures. This finding was further supported by Bayes Factor analyses which indicated moderate levels of support for the null hypothesis overall. This initial pilot study therefore does not support single-session iTBS as an efficacious method for modulating either executive processes or WM in PD. We discuss potential reasons for this finding along with directions for future research.

Executive Functions in Alzheimer Disease: A Systematic Review

Alzheimer's disease is a severe irreversible syndrome, characterized by a slow and progressive cognitive decline that interferes with the standard instrumental and essential functions of daily life. Promptly identifying the impairment of particular cognitive functions could be a fundamental condition to limit, through preventive or therapeutic interventions, the functional damages found in this degenerative dementia. This study aims to analyse, through a systematic review of the studies, the sensitivity of four experimental paradigms (Wisconsin Card Sorting Test, Stroop Task, Go/No-Go Task, and Flanker Task) considered as golden standard instruments for executive functions assessment in elderly subjects affected by Alzheimer dementia. This review was carried out according to the PRISMA method. Forty-five studies comparing the executive performance of patients with Alzheimer's dementia (diagnosed according to different classification criteria for dementia) and healthy elderly patients both over the age of sixty, were selected. For the research, PubMed, PsycINFO, PsycArticles databases were used. The study highlighted the importance of using standard protocols to evaluate executive dysfunction in Alzheimer's disease. The Stroop task allows discriminating better between healthy and pathological aging.

Diagnostic Utility of the Shortened Version of the Wisconsin Card Sorting Test in Patients With Sporadic Late Onset Alzheimer Disease

BACKGROUND

The classic version of the Wisconsin Card Sorting Test (WCST) consists of correctly sorting 128 cards according to changing sorting criteria. Its application is costly in terms of the time employed, with all the negative consequences this entails (decrease in motivation, frustration, and fatigue).

METHOD

The main objective of this study was to test the usefulness of the shortened version of the WCST as compared to the full test by analyzing the equivalence between the two decks comprising the full 128-card version on a sample of patients diagnosed with sporadic late onset Alzheimer disease (SLOAD) and to check its clinical usefulness.

RESULTS

The variables showed equivalence between the two decks and their ability to differentiate between the control group (CG) and the Alzheimer disease (AD) group.

CONCLUSION

The scores obtained suggest equivalence between decks and that the application of only the first deck is sufficient.

Behavioural inflexibility in a comorbid rat model of striatal ischemic injury and mutant hAPP overexpression

Alzheimer disease (AD) and stroke coexist and interact; yet how they interact is not sufficiently understood. Both AD and basal ganglia stroke can impair behavioural flexibility, which can be reliably modeled in rats using an established operant based set-shifting test. Transgenic Fischer 344-APP21 rats (TgF344) overexpress pathogenic human amyloid precursor protein (hAPP) but do not spontaneously develop overt pathology, hence TgF344 rats can be used to model the effect of vascular injury in the prodromal stages of Alzheimer disease. We demonstrate that the injection of endothelin-1 (ET1) into the dorsal striatum of TgF344 rats (Tg-ET1) produced an exacerbation of behavioural inflexibility with a behavioural phenotype that was distinct from saline-injected wildtype & TgF344 rats as well as ET1-injected wildtype rats (Wt-ET1). In addition to profiling the types of errors made, interpolative modeling using logistic exposure-response regression provided an informative analysis of the timing and efficiency of behavioural flexibility. During set-shifting, Tg-ET1 committed fewer perseverative errors than Wt-ET1. However, Tg-ET1 committed significantly more regressive errors and had a less efficient strategy change than all other groups. Thus, behavioural flexibility was more vulnerable to striatal ischemic injury in TgF344 rats.

Mild Cognitive Impairment in Parkinson's Disease: Clustering and Switching Analyses in Verbal Fluency Test

OBJECTIVES

Mild cognitive impairment is common in non-demented Parkinson disease patients (PD-MCI) and is considered as a risk factor for dementia. Executive dysfunction has been widely described in PD and the Verbal Fluency Tests (VFT) are often used for executive function assessment in this pathology. The Movement Disorder Society (MDS) published guidelines for PD-MCI diagnosis in 2012. However, no investigation has focused on the qualitative analysis of VFT in PD-MCI. The aim of this work was to study the clustering and switching strategies in VFT in PD-MCI patients. Moreover, these variables are considered as predictors for PD-MCI diagnosis.

METHODS

Forty-three PD patients and twenty normal controls were evaluated with a neuropsychological protocol and the MDS criteria for PD-MCI were applied. Clustering and switching analysis were conducted for VFT.

RESULTS

The percentage of patients diagnosed with PD-MCI was 37.2%. The Mann-Whitney U test analysis showed that PD-MCI performed poorly in different cognitive measures (digit span, Wisconsin Card Sorting Test, judgment of line orientation, and comprehension test), compared to PD patients without mild cognitive impairment (PD-nMCI). Phonemic fluency analyses showed that PD-MCI patients produced fewer words and switched significantly less, compared to controls and PD-nMCI. Concerning semantic fluency, the PD-MCI group differed significantly, compared to controls and PD-nMCI, in switches. Discriminant function analyses and logistic regression analyses revealed that switches predicted PD-MCI.

CONCLUSIONS

PD-MCI patients showed poor performance in VFT related to the deficient use of production strategies. The number of switches is a useful predictor for incident PD-MCI. (JINS, 2017, 23, 511-520).

Cognitive flexibility: A trait of bipolar disorder that worsens with length of illness

INTRODUCTION

Deficits in cognitive flexibility, a difficulty altering thoughts and behavioral responses in a changing environment, are found in individuals with bipolar disorder (BD) and are associated with poor social and work functioning. However, the current literature is inconsistent in clarifying the long-term nature of these deficits for those with BD. We administered a common task of cognitive flexibility, the Wisconsin Card Sorting Task (WCST) and accounted for demographics, clinical, and cognitive features of BD, to determine the state versus trait characteristics of these deficits.

METHOD

The Wisconsin Card Sorting Test (WCST) was administered to 154 adults with BD and 95 healthy controls twice, one year apart.

RESULTS

The main findings show that cognitive inflexibility is a trait feature of BD, independent of clinical features, that may modestly worsen over time due to the presence of certain demographic, cognitive, and functional features of the disorder. In addition, improvements in WCST performance over an extended period of time in both those with and those without already existing cognitive flexibility deficits indicate potential practice effects.

CONCLUSIONS

These findings suggest that the implementation of early interventions before the illness progresses could potentially prevent further cognitive impairment, mitigate functional outcomes, and improve the quality of life of the individual with BD.

Anterior cingulate dopamine turnover and behavior change in Parkinson's disease

Subtle cognitive and behavioral changes are common in early Parkinson's disease. The cause of these symptoms is probably multifactorial but may in part be related to extra-striatal dopamine levels. 6-[(18) F]-Fluoro-L-dopa (FDOPA) positron emission tomography has been widely used to quantify dopamine metabolism in the brain; the most frequently measured kinetic parameter is the tissue uptake rate constant, Ki. However, estimates of dopamine turnover, which also account for the small rate of FDOPA loss from areas of specific trapping, may be more sensitive than Ki for early disease-related changes in dopamine biosynthesis. The purpose of the present study was to compare effective distribution volume ratio (eDVR), a metric for dopamine turnover, to cognitive and behavioral measures in Parkinson's patients. We chose to focus the investigation on anterior cingulate cortex, which shows highest FDOPA uptake within frontal regions and has known roles in executive function. Fifteen non-demented early-stage PD patients were pretreated with carbidopa and tolcapone, a central catechol-O-methyl transferase (COMT) inhibitor, and then underwent extended imaging with FDOPA PET. Anterior cingulate eDVR was compared with composite scores for language, memory, and executive function measured by neuropsychological testing, and behavior change measured using two informant-based questionnaires, the Cambridge Behavioral Inventory and the Behavior Rating Inventory of Executive Function-Adult Version. Lower mean eDVR (thus higher dopamine turnover) in anterior cingulate cortex was related to lower (more impaired) behavior scores. We conclude that subtle changes in anterior cingulate dopamine metabolism may contribute to dysexecutive behaviors in Parkinson's disease.

The Gothenburg MCI study: Design and distribution of Alzheimer's disease and subcortical vascular disease diagnoses from baseline to 6-year follow-up

There is a need for increased nosological knowledge to enable rational trials in Alzheimer’s disease (AD) and related disorders. The ongoing Gothenburg mild cognitive impairment (MCI) study is an attempt to conduct longitudinal in-depth phenotyping of patients with different forms and degrees of cognitive impairment using neuropsychological, neuroimaging, and neurochemical tools. Particular attention is paid to the interplay between AD and subcortical vascular disease, the latter representing a disease entity that may cause or contribute to cognitive impairment with an effect size that may be comparable to AD. Of 664 patients enrolled between 1999 and 2013, 195 were diagnosed with subjective cognitive impairment (SCI), 274 with mild cognitive impairment (MCI), and 195 with dementia, at baseline. Of the 195 (29%) patients with dementia at baseline, 81 (42%) had AD, 27 (14%) SVD, 41 (21%) mixed type dementia (=AD + SVD = MixD), and 46 (23%) other etiologies. After 6 years, 292 SCI/MCI patients were eligible for follow-up. Of these 292, 69 (24%) had converted to dementia (29 (42%) AD, 16 (23%) SVD, 15 (22%) MixD, 9 (13%) other etiologies). The study has shown that it is possible to identify not only AD but also incipient and manifest MixD/SVD in a memory clinic setting. These conditions should be taken into account in clinical trials.

Improving executive function using transcranial infrared laser stimulation

Transcranial infrared laser stimulation is a new non-invasive form of low-level light therapy that may have a wide range of neuropsychological applications. It entails using low-power and high-energy-density infrared light from lasers to increase metabolic energy. Preclinical work showed that this intervention can increase cortical metabolic energy, thereby improving frontal cortex-based memory function in rats. Barrett and Gonzalez-Lima (2013, Neuroscience, 230, 13) discovered that transcranial laser stimulation can enhance sustained attention and short-term memory in humans. We extend this line of work to executive function. Specifically, we ask whether transcranial laser stimulation enhances performance in the Wisconsin Card Sorting Task that is considered the gold standard of executive function and is compromised in normal ageing and a number of neuropsychological disorders. We used a laser of a specific wavelength (1,064 nm) that photostimulates cytochrome oxidase - the enzyme catalysing oxygen consumption for metabolic energy production. Increased cytochrome oxidase activity is considered the primary mechanism of action of this intervention. Participants who received laser treatment made fewer errors and showed improved set-shifting ability relative to placebo controls. These results suggest that transcranial laser stimulation improves executive function and may have exciting potential for treating or preventing deficits resulting from neuropsychological disorders or normal ageing.

Simple and complex rule induction performance in young and older adults: contribution of episodic memory and working memory

This study tested the hypothesis that part of the age-related decline in performance on executive function tasks is due to a decline in episodic memory. For this, we developed a rule induction task in which we manipulated the involvement of episodic memory and executive control processes; age effects and neuropsychological predictors of task performance were investigated. Twenty-six younger (mean age, 24.0; range, 19-35 years) and 27 community-dwelling older adults (mean age, 67.5; range, 50-91 years) participated. The neuropsychological predictors consisted of the performance on tests of episodic memory, working memory, switching, inhibition and flexibility. Performance of the older adults was worse for the learning and memorization of simple rules, as well as for the more demanding executive control condition requiring the manipulation of informational content. Episodic memory was the only predictor of performance on the simple learning and memorization task condition whereas an increase in rule induction complexity additionally engaged working memory processes. Together, these findings indicate that part of the age-related decline on rule induction tests may be the result of a decline in episodic memory. Further studies are needed that examine the role of episodic memory in other executive function tasks in aging.

White matter microstructural integrity and executive function in Parkinson's disease

Recent studies suggest that white matter abnormalities contribute to both motor and non-motor symptoms of Parkinson’s disease. The present study was designed to investigate the degree to which diffusion tensor magnetic resonance imaging (DTI) indices are related to executive function in Parkinson’s patients. We used tract-based spatial statistics to compare DTI data from 15 patients to 15 healthy, age- and education-matched controls. We then extracted mean values of fractional anisotropy (FA) and mean diffusivity (MD) within an a priori frontal mask. Executive function composite Z scores were regressed against these DTI indices, age, and total intracranial volume. In Parkinson’s patients, FA was related to executive composite scores, and both indices were related to Stroop interference scores. We conclude that white matter microstructural abnormalities contribute to cognitive deficits in Parkinson’s disease. Further work is needed to determine whether these white matter changes reflect the pathological process or a clinically important comorbidity.

Cognitive disorganisation in schizotypy is associated with deterioration in visual backward masking

To understand the causes of schizophrenia, a search for stable markers (endophenotypes) is ongoing. In previous years, we have shown that the shine-through visual backward masking paradigm meets the most important characteristics of an endophenotype. Here, we tested masking performance differences between healthy students with low and high schizotypy scores as determined by the self-report O-Life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experiences), cognitive disorganisation, and negative schizotypy (introvertive anhedonia). Forty participants performed the shine-through backward masking task and a classical cognitive test, the Wisconsin Card Sorting Task (WCST). We found that visual backward masking was impaired for students scoring high as compared to low on the cognitive disorganisation dimension, whereas the positive and negative schizotypy dimensions showed no link to masking performance. We also found group differences for students scoring high and low on the cognitive disorganisation factor for the WCST. These findings indicate that the shine-through paradigm is sensitive to differences in schizotypy which are closely linked with the pathological expression in schizophrenia.

Dementia in Parkinson's disease

Parkinson's disease is the second most common neurodegenerative illness diagnosed in the United States. Dementia is recognized as a common component of advanced Parkinson's disease (PD). In patients with early PD, cognitive changes occur and primarily reflect impairment in executive function. It is unknown if the early cognitive changes detected on neuropsychological testing in Parkinson's disease are predictive of the subsequent development of Parkinson's disease with dementia (PDD). Many patients with PD develop dementia characterized by a wide range of cognitive deficits distinct from those seen in Alzheimer's disease (AD). Neuropsychiatric problems frequently accompany PDD. This chapter reviews the epidemiology, clinical characteristics of early and late cognitive changes, pathology, neuroimaging, diagnosis, and treatment of PDD.

Neuropsychological characteristics of dementia with Lewy bodies and Parkinson's disease with dementia: differentiation, early detection, and implications for "mild cognitive impairment" and biomarkers

Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) are neurodegenerative conditions sharing a disorder of alpha-synuclein metabolism. Temporal differences in the emergence of symptoms and clinical features warrant the continued clinical distinction between DLB and PDD. While DLB and PDD groups' neuropsychological profiles often differ from those in Alzheimer's disease (AD), the diagnostic sensitivity, specificity, and predictive values of these profiles remain largely unknown. PDD and DLB neuropsychological profiles share sufficient similarity to resist accurate and reliable differentiation. Although heterogeneous cognitive changes (predominantly in memory and executive function) may manifest earlier and more frequently than previously appreciated in Parkinson's disease (PD), and executive deficits may be harbingers of dementia, the enthusiasm to uncritically extend the concept of mild cognitive impairment (MCI) to PD should be tempered. Instead, future research might strive to identify the precise neuropsychological characteristics of the prodromal stages of PD, PDD, and DLB which, in conjunction with other potential biomarkers, facilitate early and accurate diagnosis, and the definition of neuroprotective, neurorestorative, and symptomatic treatment endpoints.

Construct Validity of the Wisconsin Card Sorting Test-64 in Patients with Stroke

This study examined the factor structure and contrasted-group validity of the Wisconsin Card Sorting Test-64 (WCST-64) in a stroke sample (n = 112). Confirmatory factor analyses were used to compare five different models suggested by prior factor analyses. The results indicated that the WCST-64 was best represented by a three-dimensional model comprising response inflexibility (factor 1), ineffective hypothesis-testing strategy (factor 2), and set maintenance (factor 3). A significant overall multivariate effect for group (F = 2.87, df = 18,495.46, p <.001) was found in a multivariate analysis of covariance with WCST scores as dependent variables and four different groups (three stroke subgroups with different levels of cognitive function and a normal control group) as independent variable, after controlling for gender. The results of discriminant analysis supported the use of the WCST-64 in stroke patients with cognitive impairment.

Clinical diagnostic criteria for dementia associated with Parkinson's disease

Dementia has been increasingly more recognized to be a common feature in patients with Parkinson's disease (PD), especially in old age. Specific criteria for the clinical diagnosis of dementia associated with PD (PD-D), however, have been lacking. A Task Force, organized by the Movement Disorder Study, was charged with the development of clinical diagnostic criteria for PD-D. The Task Force members were assigned to sub-committees and performed a systematic review of the literature, based on pre-defined selection criteria, in order to identify the epidemiological, clinical, auxillary, and pathological features of PD-D. Clinical diagnostic criteria were then developed based on these findings and group consensus. The incidence of dementia in PD is increased up to six times, point-prevelance is close to 30%, older age and akinetic-rigid form are associated with higher risk. PD-D is characterized by impairment in attention, memory, executive and visuo-spatial functions, behavioral symptoms such as affective changes, hallucinations, and apathy are frequent. There are no specific ancillary investigations for the diagnosis; the main pathological correlate is Lewy body-type degeneration in cerebral cortex and limbic structures. Based on the characteristic features associated with this condition, clinical diagnostic criteria for probable and possible PD-D are proposed.

Complicated vs uncomplicated mild traumatic brain injury: acute neuropsychological outcome

PRIMARY OBJECTIVE

The purpose of this study was to carefully examine the effects of a complicated vs uncomplicated mild traumatic brain injury (MTBI) on acute neuropsychological outcome.

RESEARCH DESIGN

Participants were derived from an archival trauma database. This is a retrospective matched groups design.

METHODS AND PROCEDURES

All patients were seen through a Head Injury Trauma Service clinical pathway. To be included, all patients must have undergone a day-of-injury CT scan and completed a small battery of neuropsychological tests within 2 weeks of injury. Patients were sorted into two groups on the basis of having a normal or abnormal CT scan. Patients were then carefully matched on age, education, gender and mode of injury (e.g. car accident, fall or assault). The final sample consisted of 100 patients, with 50 in each group.

MAIN OUTCOMES AND RESULTS

The patients with complicated MTBIs performed significantly more poorly on some of the neuropsychological tests. However, the effect sizes were small or medium and the two groups could not be differentiated using logistic regression analysis.

CONCLUSIONS

The reasons why people recover slowly or fail to recover fully from MTBIs remain poorly understood. Visible structural brain damage carries increased risk for slow and incomplete recovery, but certainly does not provide an explanation for good or poor outcome in the majority of patients.

Impact of the COMT Val108/158 Met and DAT genotypes on prefrontal function in healthy subjects

Two limiting factors of dopamine activity are the catechol-o-methyltransferase (COMT) and the dopamine transporter (DAT), which terminate dopamine activity by degradation and uptake, respectively. Genetic variants of COMT and DAT have been related to the enzymatic activity and protein availability, respectively. The Met allele of the COMT Val108/158 Met polymorphism has been associated to lower enzymatic activity and the 9-repeat allele of the DAT 40 base-pair (bp) variable number of tandem repeat (VNTR) polymorphism has been related to lower protein availability. Genotypes for COMT and DAT were determined in a sample of 75 healthy subjects, who underwent functional magnetic resonance imaging (fMRI) while performing an N-back task. To further assess the effects of the genotypes on cognition, subjects were administered the Wisconsin Card Sorting Test (WCST) and the Continuous Performance Test (CPT). Analysis of fMRI data revealed an additive effect of these two genes on brain activation in an N-back task, with subjects homozygous for the Val and the 9-repeat alleles showing the highest activation for the same level of performance. Moreover, the Val allele was related to higher number of perseverative errors on the WCST and with a higher number of commission errors on the CPT. The 10-repeat allele was associated with faster reaction times but also with a higher number of commission errors. Our results support a role of the COMT Val108/158 Met and the DAT 40 bp VNTR in both brain activation and cognition.

Heterogeneity in executive impairment in patients with very mild Alzheimer's disease

BACKGROUND/AIMS

The presence of executive impairment in mild Alzheimer's disease (AD) has primarily been demonstrated by means of group comparison. Whether executive dysfunction is a common feature of mild AD or only present in a subgroup of patients remains unclear. The aim of this study was to describe the frequency of impairment on a set of internationally well-known executive tests in patients with very mild AD.

METHODS

Thirty-six patients with very mild AD (MMSE scores above 23) and 32 healthy control subjects were administered a battery of 7 executive tests: Trail Making part B, Stroop Interference Test, modified Wisconsin Card Sorting Test (WCST), category- and letter-based verbal fluency, a design fluency task and the Similarities subtest from WAIS. Impairment was defined as a score of 2 SD or more below control means.

RESULTS

Executive impairment on at least 1 measure was seen in 76% of the patients, and 50% were impaired on 2 or more tests. Trail Making B and Stroop Interference Test were impaired in more than 40%, whereas only few patients were impaired on Similarities, WCST and design fluency. A wide variation of executive test profiles was seen among the patients.

CONCLUSION

Executive impairments are common in early AD and not just a feature characteristic of a subgroup of patients. Complex attentional skills are more frequently affected than other executive functions. There is, however, considerable heterogeneity among AD patients in the pattern of executive dysfunction.

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.

Early discrimination reversal learning impairment and preserved spatial learning in a longitudinal study of Tg2576 APPsw mice

To understand the relationship between amyloid-beta and cognitive decline in Alzheimer's disease, we evaluated cortical and hippocampal function in a transgenic mouse model of amyloid over-expression in Alzheimer's disease, the Tg2576 mouse. Tg2576 mice and their non-transgenic littermates were assessed at both 6 and 14 months of age in a battery of cognitive tests: attentional set-shifting, water maze spatial reference memory and T-maze working memory. Spatial reference memory was not affected by Tg status at either age. Working memory was only affected by age, with 6-month-old mice performing better than 14-month-old ones. Older mice were also significantly impaired on reversal learning and on the intra- and extra-dimensional shift in attentional set-shifting. A significant transgene effect was apparent in reversal learning, with Tg2576 mice requiring more trials to reach criterion at 6 months old. These data indicate that the effects of normal aging in C57B6xSJL F1 mice are most pronounced on putative frontal cortex-dependent tasks and that increasing Abeta load only affects discrimination reversal learning in our study.

Wisconsin Card Sorting Test performance after putaminal hemorrhagic stroke

The purpose of this study was to compare the performance differences in the Wisconsin Card Sorting Test (WCST) between 55 patients with putaminal hemorrhage (PH) 3 months after stroke and 69 age-matched normal controls. Impairment on WCST was defined as performance greater than 1.64 standard deviation below the control mean. A multivariate analysis of covariance (MANCOVA) controlling for education yielded a significant main effect for group but not for education and interaction of group x education. Univariate analyses revealed significant between-group differences in five WCST measures, including perseverative errors (PE), perseverative responses (PR), conceptual-level responses (CLR), number of categories completed (NCC), and trials to complete the first category (TCC). For patients with PH, z-scores for two WCST indices were within the impaired range: TCC and PR. A high percentage of patients (40-47%) scored in the designated impaired range on NCC, PR, PE, and TCC. The WCST variables discriminated patients from controls with an overall accurate classification rate of 91.9%. Of these, the variables that contributed most to the differentiation between patients and normal controls were PE, CLR, and total number correct (TNC) (a standardized canonical discriminant function coefficient > 0.40). Finally, no significant hemispheric laterality effects emerged on any of the WCST variables. The results of this study provide further evidence of impaired mental set shifting in stroke patients with PH. The implications for rehabilitation professionals are discussed, and recommendations for further research are made.

When artificial grammar acquisition in Parkinson's disease is impaired: the case of learning via trial-by-trial feedback

Although there is strong evidence that human category learning is mediated by qualitatively distinct systems, the neural substrates of procedural category learning remain largely unclear. The present research sought to investigate the role of the basal ganglia in the acquisition of categorical knowledge via an examination of the ability of people with Parkinson's disease (PD) to learn an artificial grammar (AG) system in a format akin to habit learning tasks such as probabilistic classification learning. Eighteen nondemented patients with PD were compared with 22 matched controls on a task modified so that participants' grammar learning depended on making use of feedback provided on each trial. Results showed that patients with PD exhibited abnormal AG learning, with the deficit more pronounced early in the task. Impaired categorisation performance in patients was not related to declarative knowledge obtained during the test and was independent of frontal functioning. The findings presented here indicate that prior inconsistencies across category learning tasks in PD performance may be explained, at least in part, by whether the task necessitates the formation of associations between stimulus cues and categorical responses, and support the hypothesis that the basal ganglia play a specific role in procedural learning in complex feedback-based categorisation tasks.

The Goteborg MCI study: mild cognitive impairment is a heterogeneous condition

BACKGROUND

Mild cognitive impairment (MCI) has been considered a transitional state between normal aging and dementia, characterised by memory impairment but normal general cognitive functioning. Recently other cognitive deficits have been reported. This has led to a modification of MCI criteria.

OBJECTIVE

To examine which neuropsychological tests most clearly distinguish MCI subjects from normal controls.

METHODS

112 consecutive MCI subjects and 35 controls were included in the study. The diagnosis of MCI was based on an objective history of cognitive decline and a neuropsychiatric examination, comprising instruments STEP, I-Flex, MMSE, and CDR. Participants were examined with 21 neuropsychological tests in the cognitive domains speed/attention, memory and learning, visuospatial function, language, and executive function.

RESULTS

Controls were significantly older. No differences were found in education or general intellectual capacity. Controls performed significantly better than MCI on tests within all five cognitive domains. The clearest differences were seen on language tests, followed by executive function, and learning and memory. Only two subjects (1.8%) were purely amnestic; 17% showed no impairment compared with controls, with a cut off of 1.5 SD below age mean. These subjects were better educated and performed significantly better on measures of general cognitive capacity.

CONCLUSIONS

The results illustrate the heterogeneity of MCI, with a significant degree of impairment in all five cognitive domains. When examined with a comprehensive neuropsychological battery, very few subjects had an isolated memory impairment.

Impaired higher order implicit sequence learning on the verbal version of the serial reaction time task in patients with Parkinson's disease

Although neuroimaging studies have strongly implicated basal ganglia involvement in implicit sequence learning, serial reaction time (SRT) studies with Parkinson's disease (PD) patients have yielded mixed results. The present research sought to examine the ability of people with PD to implicitly learn sequences with different sequential structures and to objectively assess explicit knowledge. A version of the SRT task that reduces motor demands was used to compare 19 patients with PD but not dementia and 37 matched controls. PD patients showed less implicit sequence-specific learning for both sequences and reduced response time improvement over sequential trials for the more complex sequence. A closer examination revealed that the deficit involved higher order sequential associations as well as the learning of pairwise information.

[Methods for assessing cognitive function utilizing operant tasks in rats]

Most human behaviors (responses) are volitional, the frequency of which is changed based on stimulus presentations contingent upon the response, that is, operant behavior. It is considered that the findings on cognitive functions based on operant behaviors are more reliable in extrapolating the results to humans. Impairment of memory function, most notably the impairments of working memory and attention, is an important research focus to elucidate the mechanism underlying the core syndrome of Alzheimer's disease. Among various methods to measure working memory and attention, a delayed matching-to-sample paradigm utilizing operant chambers equipped with 3 levers and a choice reaction time paradigm have been proven to be very useful. Aside from these, adaptation to new environment is an important function for survival, and its impairment has been considered to be one of the factors inducing psychiatric disorders. Preclinical methods to measure the adaptation ability include a position reversal learning paradigm utilizing 2-lever operant chambers. Since the findings of studies on cognitive functions utilizing operant behaviors have been in good correlation with clinical findings, it would serve as a good strategy for elucidating the causes of such disorders as well as developing therapeutic agents.

Inhibitory functioning in Alzheimer’s disease

We present a comprehensive review of studies assessing inhibitory functioning in Alzheimer's disease. The objectives of this review are: (i) to establish whether Alzheimer's disease affects all inhibitory mechanisms equally, and (ii) where possible, to assess whether any effects of Alzheimer's disease on inhibition tasks might be caused by other cognitive deficits, such as slowed processing. We review inhibitory mechanisms considered to play a crucial role in various domains of cognition, such as inhibition involved in working memory, selective attention and shifting abilities, and the inhibition of motor and verbal responses. It was found that whilst most inhibitory mechanisms are affected by the disorder, some are relatively preserved, suggesting that inhibitory deficits in Alzheimer's disease may not be the result of a general inhibitory breakdown. In particular, the experimental results reviewed showed that Alzheimer's disease has a strong effect on tasks requiring controlled inhibition processes, such as the Stroop task. However, the presence of the disease appears to have relatively little effect on tasks requiring more automatic inhibition, such as the inhibition of return task. Thus, the distinction between automatic, reflexive inhibitory mechanisms and controlled inhibitory mechanisms may be critical when predicting the integrity of inhibitory mechanisms in Alzheimer's disease. Substantial effects of Alzheimer's disease on tasks such as negative priming, which are not cognitively complex but do require some degree of controlled inhibition, support this hypothesis. A meta-analytic review of seven studies on the Stroop paradigm revealed substantially larger effects of Alzheimer's disease on the inhibition condition relative to the baseline condition, suggesting that these deficits do not simply reflect general slowing.

Comparability of the Standard WCST and WCST–64 in Traumatic Brain Injury

The aim of this study was to investigate the comparability of the Wisconsin Card Sorting Test short form (WCST-64) to the standard form in a clinical population with documented brain pathology: chronic severe traumatic brain injury (TBI). Participants were 61 patients at least 1 year after severe TBI living at a large residential rehabilitation facility. The WCST was administered in standard fashion with both the standard and 64-card versions scored. All derived scores with norms were examined. Results indicated that the WCST-64 scores were comparable to the standard version, and assigned impairment levels remained relatively stable. These results suggest the WCST-64 is a valid alternative to the standard version in chronic severe TBI.

Clinical normative data for the WCST-64 following uncomplicated mild head injury

Clinical norms for the 64-item Wisconsin Card Sorting Test (WCST-64) are presented. The norms were derived from 303 persons presenting for emergency services who met criteria for uncomplicated mild head injury. Most data were obtained within 2 days of injury, and the remaining data were obtained within 10 days of injury. The norms may be used to help determine whether or not a person's scores on the WCST-64 are typical of those seen shortly after sustaining an uncomplicated mild head injury.

Neuropsychologische Befunde bei der Diagnostik hirnorganischer Erkrankungen mit Demenz

Zusammenfassung: Auf der Basis einer retrospektiven Untersuchung von 175 Patienten, die im Laufe der letzten 4 Jahre mit der klinischen Verdachtsdiagnose einer Demenz in unserer Abteilung vorgestellt wurden, werden die neuropsychologischen Defizite verschiedener Patientengruppen mit Morbus Parkinson, Chorea Huntington (HD), Multisystematrophien, vaskulärer subcorticaler Encephalopathie, Normaldruck-Hydrocephalus und wahrscheinlicher Alzheimerscher Erkrankung (AD) verglichen. Die Ergebnisse zeigen bei allen Patientengruppen schwere Beeinträchtigungen in den Bereichen Aufmerksamkeit und exekutive Funktionen ohne signifikante Unterschiede zwischen den einzelnen Diagnosegruppen. Eine deutliche Clusterbildung in bezug auf stärkere Beeinträchtigungen zeigt sich hingegen bezüglich längerfristigen Gedächtnisleistungen (HD und AD) sowie bei aphasischen, sprachassoziierten und apraktischen Störungen (AD). Auf Basis dieser Befunde werden die möglichen Implikationen der neuropsychologischen Diagnostik für die Differentialdiagnostik der Demenz diskutiert.

A neuropsychological comparison of demented and nondemented patients with Parkinson's disease

The strength and sensitivity of neuropsychological test findings in patients with Parkinson's disease (PD) was reviewed using meta-analytic principles to provide a basis of comparison of deficits in nondemented and demented patients with PD. The review revealed significant relationships among duration of disease, physical disability, and cognitive impairment in nondemented patients, and qualitative and quantitative differences in the pattern of neuropsychological test impairments between nondemented and demented patients with PD. The disparate profiles of neuropsychological impairment in nondemented and demented patients may indeed reflect disease progression in keeping with the significant clinical correlations in nondemented patients. That is, as the duration of the disease endures, it appears that performance on tasks of delayed recall deteriorates first, followed by performance on measures of manual dexterity, cognitive flexibility, and abstraction.