Visuospatial planning and problem solving in Alzheimer's disease patients: a study with the Tower of London Test

Towers of Kuwait Arabic Neurocognitive Assessment: A novel executive and visuospatial functions assessment tool added to the CERAD neuropsychological battery-Arabic version (CERAD-ArNB)

Assessment of executive and visuospatial neurocognitive domains is lacking in the Omani population, especially for elderly individuals with low educational levels. Therefore, the Towers of Kuwait-Arabic Neurocognitive Assessment (ToK-ArNA) was developed using similar psychometric features of Tower of London (ToL) test, and the unique architecture of Towers of Kuwait, with the potential to overcome the limitation of ToL color perception difficulties that might be encountered in subjects with hereditary or acquired color vision disorders. We enrolled 120 older Arabic-speaking Omanis from January 2022 to November 2022 and all participants underwent screening to ensure normal cognitive function before performing the ToL and ToK-ArNA tests. Validity, reliability, and non-parametric statistical tests were used for data analysis. A total of 85 participants, 51 men (60%) and 34 women (40%) met the inclusion criteria and completed the testing. Statistical analyses confirmed the validity and reliability of ToK-ArNA compared to ToL, with comparable total Time and Accuracy scores and more preference towered the ToK-ArNA among the participants. Despite the study limitations, these results indicate that the ToK-ArNA is a reliable and applicable executive and visuospatial function assessment tool and further studies are warranted to establish its validity in patients with various neurocognitive disorders.

Feasibility and Preliminary Efficacy of American Elderberry Juice for Improving Cognition and Inflammation in Patients with Mild Cognitive Impairment

Despite data showing that nutritional interventions high in antioxidant/anti-inflammatory properties (anthocyanin-rich foods, such as blueberries/elderberries) may decrease risk of memory loss and cognitive decline, evidence for such effects in mild cognitive impairment (MCI) is limited. This study examined preliminary effects of American elderberry (Sambucus nigra subsp. canadensis) juice on cognition and inflammatory markers in patients with MCI. In a randomized, double-blind, placebo-controlled trial, patients with MCI (n = 24, Mage = 76.33 ± 6.95) received American elderberry (n = 11) or placebo (n = 13) juice (5 mL orally 3 times a day) for 6 months. At baseline, 3 months, and 6 months, patients completed tasks measuring global cognition, verbal memory, language, visuospatial cognitive flexibility/problem solving, and memory. A subsample (n = 12, 7 elderberry/5 placebo) provided blood samples to measure serum inflammatory markers. Multilevel models examined effects of the condition (elderberry/placebo), time (baseline/3 months/6 months), and condition by time interactions on cognition/inflammation outcomes. Attrition rates for elderberry (18%) and placebo (15%) conditions were fairly low. The dosage compliance (elderberry-97%; placebo-97%) and completion of cognitive (elderberry-88%; placebo-87%) and blood-based (elderberry-100%; placebo-100%) assessments was high. Elderberry (not placebo) trended (p = 0.09) towards faster visuospatial problem solving performance from baseline to 6 months. For the elderberry condition, there were significant or significantly trending decreases over time across several markers of low-grade peripheral inflammation, including vasorin, prenylcysteine oxidase 1, and complement Factor D. Only one inflammatory marker showed an increase over time (alpha-2-macroglobin). In contrast, for the placebo, several inflammatory marker levels increased across time (L-lactate dehydrogenase B chain, complement Factor D), with one showing deceased levels over time (L-lactate dehydrogenase A chain). Daily elderberry juice consumption in patients with MCI is feasible and well tolerated and may provide some benefit to visuospatial cognitive flexibility. Preliminary findings suggest elderberry juice may reduce low-grade inflammation compared to a placebo-control. These promising findings support the need for larger, more definitive prospective studies with longer follow-ups to better understand mechanisms of action and the clinical utility of elderberries for potentially mitigating cognitive decline.

Frequency dependent whole-brain coactivation patterns analysis in Alzheimer's disease

Background

The brain in resting state has complex dynamic properties and shows frequency dependent characteristics. The frequency-dependent whole-brain dynamic changes of resting state across the scans have been ignored in Alzheimer's disease (AD).

Objective

Coactivation pattern (CAP) analysis can identify different brain states. This paper aimed to investigate the dynamic characteristics of frequency dependent whole-brain CAPs in AD.

Methods

We utilized a multiband CAP approach to model the state space and study brain dynamics in both AD and NC. The correlation between the dynamic characteristics and the subjects' clinical index was further analyzed.

Results

The results showed similar CAP patterns at different frequency bands, but the occurrence of patterns was different. In addition, CAPs associated with the default mode network (DMN) and the ventral/dorsal visual network (dorsal/ventral VN) were altered significantly between the AD and NC groups. This study also found the correlation between the altered dynamic characteristics of frequency dependent CAPs and the patients' clinical Mini-Mental State Examination assessment scale scores.

Conclusion

This study revealed that while similar CAP spatial patterns appear in different frequency bands, their dynamic characteristics in subbands vary. In addition, delineating subbands was more helpful in distinguishing AD from NC in terms of CAP.

Normative data for the Tower of London (Drexel version) in the Quebec-French population aged between 50 and 88 years

The Tower of London (ToL) is a neuropsychological test used to assess several executive functions such as strategical reasoning, mental planning, and problem-solving. Like other cognitive tests, performance on the ToL can vary according to age, level of education, sex, and cultural background of individuals. The present study aimed to establish normative data for the Drexel version of the ToL among French-Quebec people aged 50 years and over. The normative sample consisted of 174 healthy individuals aged 50-88 years, all from the province of Quebec, Canada. Analyses were performed to estimate the associations between age, sex, and education level on one hand, and ToL performance, on the other hand. Results indicated that Total Execution Time was associated with age, whereas the Total Type II Errors and Total Rule Violation score (Type I + II Errors) were associated with both age and education level. All other scores were not significantly associated with the demographic characteristics of the participants. Since the distributions of the data were all skewed, the normative data are presented in the form of percentile ranks. To conclude, the present norms will ease the detection of executive impairments in French-Quebec middle-aged and older adults.

NEURONORMA Cognitive Battery Associations with Cerebrospinal Fluid Amyloid-β and Tau Levels in the Continuum of Alzheimer's Disease

BACKGROUND

Neuropsychological assessments are essential to define the cognitive profile and contribute to the diagnosis of Alzheimer's disease (AD). The progress in knowledge about the pathophysiological process of the disease has allowed conceptualizing AD through biomarkers as a biological continuum that encompasses different clinical stages.

OBJECTIVE

To explore the association between cerebrospinal fluid (CSF) biomarkers of AD and cognition using the NEURONORMA battery, in a sample of cognitively unimpaired (CU), mild cognitive impaired (MCI), and mild dementia of the Alzheimer type (DAT) subjects, and to characterize the cognitive profiles in MCI subjects classified by A/T/N system.

METHODS

42 CU, 35 MCI, and 35 mild DAT were assessed using the NEURONORMA battery. Core AD biomarkers [amyloid-β42 (Aβ42) peptide, total tau (t-tau), and phosphorylated tau 181 (p-tau181)] proteins were measured in CSF. Correlation coefficients, multivariate regression, and effect sizes were calculated. We explored the age- and education-adjusted cognitive profiles by A/T/N variants within the MCI group.

RESULTS

Cognitive outcomes were directly associated with CSF Aβ42 and inversely with CSF tau measures. We found differences in both biomarkers and cognitive outcomes comparing all pairs except for CSF measures between cognitively impaired groups. The highest effect size was in memory tasks and biomarkers ratios. Lower performances were in memory and executive domains in MCI subjects with AD pathology (A+T+N±) compared to those with normal levels of AD biomarkers (A- T- N).

CONCLUSION

This study provides further evidence of the validity of Spanish NEURONORMA cognitive battery to characterize cognitive impairment in the AD pathological continuum.

Planning in amnestic mild cognitive impairment: an fMRI study

INTRODUCTION

The memory impairment that is characteristic of amnestic mild cognitive impairment (aMCI) is often accompanied by difficulties in executive functioning, including planning. Though planning deficits in aMCI are well documented, their neural correlates are largely unknown, and have not yet been investigated with functional magnetic resonance imaging (fMRI).

OBJECTIVES

The aim of this study was to: (1) identify differences in brain activity and connectivity during planning in people with aMCI and cognitively healthy older adults, and (2) find whether planning-related activity and connectivity are associated with cognitive performance and symptoms of apathy.

METHODS

Twenty-five people with aMCI and 15 cognitively healthy older adults performed a visuospatial planning task (Tower of London; ToL) during fMRI. Task-related brain activation, spatial maps of task-related independent components, and seed-to-voxel functional connectivity were compared between the two groups and regressed against measures of executive functions (Trail Making Test difference score, TMT B-A; Digit Symbol Substitution Test, DSST), delayed recall (Rey Auditory Verbal Learning Test), and apathy (Apathy Evaluation Scale).

RESULTS

People with aMCI scored lower on task-switching (TMT B-A), working memory (DSST), and planning (ToL). During planning, people with aMCI had less activation in the bilateral anterior calcarine sulcus/cuneus, the bilateral temporal cortices, the left precentral gyrus, the thalamus, and the right cerebellum. Across all participants, higher planning-related activity in the supplementary motor area, the retrosplenial cortex and surrounding areas, and the right temporal cortex was related to better delayed recall. There were no between-group differences in functional connectivity, nor were there any associations between connectivity and cognition. We also did not find any associations between brain activity or connectivity and apathy.

CONCLUSION

Impaired planning in people with aMCI appears to be accompanied by lower activation in a diffuse cortico-thalamic network. Across all participants, higher planning-related activity in parieto-occipital, temporal, and frontal areas was related to better memory performance. The results point to the relevance of planning deficits for understanding aMCI and extend its clinical and neurobiological signature.

Travel Planning Ability in Right Brain-Damaged Patients: Two Case Reports

Planning ability is fundamental for goal-directed spatial navigation. Preliminary findings from patients and healthy individuals suggest that travel planning (TP)-namely, navigational planning-can be considered a distinct process from visuospatial planning (VP) ability. To shed light on this distinction, two right brain-damaged patients without hemineglect were compared with a control group on two tasks aimed at testing VP (i.e., Tower of London-16, ToL-16) and TP (i.e., Minefield Task, MFT). The former requires planning the moves to reach the right configuration of three colored beads on three pegs, whereas the latter was opportunely developed to assess TP in the navigational environment when obstacles are present. Specifically, the MFT requires participants to plan a route on a large carpet avoiding some hidden obstacles previously observed. Patient 1 showed lesions encompassing the temporoparietal region and the insula; she performed poorer than the control group on the ToL-16 but showed no deficit on the MFT. Conversely, Patient 2 showed lesions mainly located in the occipitoparietal network of spatial navigation; she performed worse than the control group on the MFT but not on the ToL-16. In both cases performances satisfied the criteria for a classical dissociation, meeting criteria for a double dissociation. These results support the idea that TP is a distinct ability and that it is dissociated from VP skills.

Planning ability impairments in probable Alzheimer's disease patients: Evidence from the Tower of London test

Alzheimer's disease (AD) is associated with progressive impairment of higher-level cognitive abilities. Previous research suggests that early impairment of executive functions occurs during the course of the disease, but few studies have specifically investigated planning ability in an AD population.

Sensitivity and specificity of executive function tests for Alzheimer's disease

Decline in executive function (EF) occurs early in Alzheimer's disease (AD) and can interfere with daily functioning. Unfortunately, little is known about the relative ability of traditional EF tests to detect these cognitive changes. Given that timely diagnosis and intervention are essential to improving functional outcome in this population, our aim was to identify the specific EF measures that best differentiated mild dementia from normal aging. Thirty-one patients with mild AD and 31 controls were administered 7 EF tests. Findings indicated significant between-group differences on all measures except Wisconsin Card Sorting Test. The remaining 6 tests displayed fair to good accuracy discriminating between AD cases and controls. Only category fluency and Tower of London test remained in the final regression model that yielded the highest AUC of 0.90, which was not statistically different from that of either test alone. Overall, most of the tests employed were valid for assessing mild EF disturbances. Specifically, the two measures can be used in isolation for quick screening or in combination to facilitate a more in-depth evaluation of EF performance. This study contributes to clinical field by testifying to the validity of various EF tests to identify AD-related compromises in this cognitive domain.

Examining the impact of formal planning on performance in older adults using a naturalistic task paradigm

Thirty-two younger adults (YAs) and 64 older adults (OAs) completed the Amap Task, a naturalistic measure designed to evaluate the formulation and execution stages of planning. Participants read a map layout of a university apartment and planned an efficient strategy to complete several tasks. To determine whether execution abilities are augmented by formulating a plan, we compared formal (i.e., written strategy) and informal (i.e., initiate task when ready without writing out a strategy) planning conditions. Participants did not have access to their plan during task execution. Amap scores were also compared with informant-report of everyday functioning. For the formal planning condition, OAs were less accurate and less efficient than YAs during the formulation stage, while there were no group differences in total formulation time for the informal planning condition. Across conditions, OAs obtained poorer execution accuracy and efficiency scores, took longer during execution, and omitted more task parts. Formal planning improved execution efficiency but not accuracy, suggesting one's approach to the task (i.e., efficiency, finesse) may improve with preplanning even if overall accuracy does not. Significant relationships between Amap scores and informant-report of everyday functioning highlight the ecological validity of the Amap as a measure sensitive to everyday planning abilities.

Differential patterns of planning impairments in Parkinson's disease and sub-clinical signs of dementia? A latent-class model-based approach

Planning impairments mark a well-documented consequence of neurodegenerative diseases such as Parkinson's disease (PD). Recently, using the Tower of London task we demonstrated that, rather than being generally impaired, PD patients selectively fail when planning requires flexible in-breadth search strategies. For a better understanding of the interindividual patterns underlying specific planning impairments, here we performed an explorative re-analysis of the original data using a latent-class model-based approach. Data-driven classification according to subjects' performance was based on a multinomial processing tree (MPT) model accommodating the impact of increased breadth versus depth of looking ahead during planning. In order to assess interindividual variability in coping with these different task demands, an extension of MPT models was used in which sample-immanent heterogeneity is accounted for by identifying different latent classes of individuals. Two latent classes were identified that differed considerably in performance for problems placing high demands on the depth of anticipatory search processes. In addition, these impairments were independent of PD diagnosis. However, latent-class mediated search depth-related deficits in planning performance were associated with poorer outcomes in dementia screenings, albeit sub-clinical. PD patients exhibited additional deficits related to the breadth of searching ahead. Taken together, results revealed dissociable impairments in specific planning processes within a single task of visuospatial problem solving. Present analyses put forward the hypothesis that cognitive sequelae of PD and sub-clinical signs of dementia may be related to differential patterns of planning impairments.

Compromised visually guided motor control in individuals with Alzheimer's disease: can reliable distinctions be observed?

Identifying the multitude of deficits associated with dementia-related illnesses such as Alzheimer's disease (AD) presents a significant challenge for many health care facilities, particularly as current screening procedures may lack the sensitivity to highlight all the relative functional deficits within these populations. Although quick assessment screening tools, such as the Mini Mental State Exam (MMSE), have been the mainstay in screening patients worldwide, there are limitations to their ability in identifying visuomotor (VM) impairment. Thus, the primary objective of this research was to evaluate the presence and level of VM ability/deficits in healthy normal controls (NC) and populations with AD. The research also aimed to demonstrate that a VM measure can be utilized successfully in a busy health care setting. Results showed a clear distinction between the AD and NC groups on the VM measure. Large effect size differences were observed between groups, particularly as the VM task progressed through its varying conditions. In addition, this novel VM assessment measure demonstrated good presentation and speed and was appropriate for frontline staff in a primary healthcare setting to undertake further examination of an individual's overall visually guided ability/control.

Executive function deficits in persons with mild cognitive impairment: a study with a Tower of London task

This study assessed executive functions in persons with mild cognitive impairment (MCI) using the Tower of London (TOL). A second objective was to study the impact of three types of problem selected according to the presence or absence of a "trigger." A trigger (T) is an incitation to the participant, at the first move, to move a ball to its final position according to the model. A positive trigger (T+) is helpful, while a negative trigger (T-) creates an obstruction. Some problems have no trigger (N). This study includes 81 participants with MCI. After follow-up, one year later, two subgroups were distinguished: (a) 51 (63%) participants did not convert or decline (stable MCI); (b) 30 (37%) participants showed significant decline or progressed to dementia (decliner MCI). Persons with MCI were compared to an older adult group matched with respect to sex, age, and education. For the successes, there was a significant group difference between the three types of problem. The post hoc analysis showed that T+ took significantly less time than N or T-. There were significantly more successes for T+ than N, and these two types of problem had more success than T-. For "total number of moves," there was no significant difference between the groups. In post hoc analysis, T- involved more moves than N or T+. In qualitative analysis, T- MCI decliners produced significantly more rule breakings than the stable MCI and controls. A dysfunction in self-monitoring is a characteristic feature of persons with MCI.

Acute effects of donepezil in healthy young adults underline the fractionation of executive functioning

The cholinergic system is involved in the modulation of both bottom-up and top-down attentional control. Top-down attention engages multiple executive control processes, but few studies have investigated whether all or selective elements of executive functions are modulated by the cholinergic system. To investigate the acute effects of the pro-cholinergic donepezil in young, healthy volunteers on distinct components of executive functions we conducted a double-blind, placebo-controlled, independent-groups design study including 42 young healthy male participants who were randomly assigned to one of three oral treatments: glucose (placebo), donepezil 5 mg or donepezil 7.5 mg. The test battery included measures of different executive components (shifting, updating, inhibition, dual-task performance, planning, access to long-term memory), tasks that evaluated arousal/vigilance/visuomotor performance, as well as functioning of working memory subsidiary systems. Donepezil improved sustained attention, reaction times, dual-task performance and the executive component of digit span. The positive effects in these executive tasks did not correlate with arousal/visuomotor/vigilance measures. Among the various executive domains investigated donepezil selectively increased dual-task performance in a manner that could not be ascribed to improvement in arousal/vigilance/visuomotor performance nor working memory slave systems. Other executive tasks that rely heavily on visuospatial processing may also be modulated by the cholinergic system.