The relationship between executive functions and fluid intelligence in Parkinson's disease

The influence of interruptions and planning on serial everyday multitasking in older adults

Cognitive aging research has studied the influence of healthy aging on the ability to multitask. Yet, little is known about the factors that might improve or impair serial multitasking performance in older adults. Three experiments involving younger and older adults assessed the impact of interruptions and planning on a prop-based test of multitasking. In Experiment 1, 26 younger adults and 25 older adults' multitasking abilities were assessed; older adults performed significantly more poorly than younger adults. In Experiment 2, 19 younger and 22 older adults were randomly allocated to a group who experienced a one minute unexpected interruption while multitasking or a group with no interruption. The results showed that, when there was an interruption, the age difference disappeared. In Experiment 3, 32 younger and 30 older adults were randomly allocated to a group who were given 3 minutes to write an outline describing how they intended to approach the multitasking task, and another group who were given 3 minutes to label pictures of everyday objects prior to multitasking. Again, when participants were encouraged to plan, no age difference was found. These results highlight the advantage that interruptions and planning might have on serial everyday multitasking performance in older adults.

Naturalistic assessment of everyday multitasking in Parkinson's disease with and without mild cognitive impairment

Objective: Multitasking is an essential part of everyday functioning often not formally assessed by traditional neuropsychological tests. Although individuals with Parkinson's disease (PD) experience both motor and cognitive difficulties, previous research has demonstrated more pronounced functional difficulties with the presence of mild cognitive impairment (PD-MCI). The current study compared individuals with PD-MCI, PD with normal cognition (PD-NC), and healthy controls on a naturalistic task of multitasking, the Day Out Task (DOT). Method: Participants were 38 healthy older adults (HOA), 23 individuals with PD-NC, and 15 individuals with PD-MCI. Participants completed a battery of neuropsychological tasks and the DOT. Informants also completed a self-reported questionnaire of participants' everyday executive functioning. Results: Compared to PD-NC and HOA, participants with PD-MCI were less accurate and efficient and took longer to complete the DOT. After controlling for motor performance, only DOT accuracy remained worse, with poorer accuracy resulted from more subtasks being left incomplete or being completed inaccurately by the PD-MCI group. DOT sequencing was a significant predictor of informant reported everyday dysexecutive symptoms. Conclusions: The findings highlight that individuals with PD-MCI are likely to experience difficulties completing complex everyday tasks due to both motor and cognitive impairments. Clinicians may therefore recommend strategies to support efficiency and accuracy in complex tasks of everyday functioning in treatment considerations.

Intelligence, cognition, and major neurocognitive disorders: From constructs to measures

The study of intelligence's role in development of major neurocognitive disorders (MND) is influenced by the approaches used to conceptualize and measure these constructs. In the field of cognitive impairment, the use of single 'intelligence' tests is a common approach to estimate intelligence. Despite being a practical compromise between feasibility and constructs, variance of these tests is only partially explained by general intelligence, and some tools (e.g., lexical tasks for premorbid intelligence) presented inherent limitations. Alternatively, factorial models allow an actual measure of intelligence as a latent factor superintending all mental abilities. Royall and colleagues used structural equation modeling to decompose the Spearman's general intelligence factor g in δ (shared variance across cognitive and functional measures) and g' (shared variance across cognitive measures only). Authors defined δ as the 'cognitive correlates of functional status', and thus a 'phenotype for all cause dementia'. Compared to g', δ explained a little rate of cognitive measures' variance, but it demonstrated a higher accuracy in dementia case-finding. From the methodological perspective, given g 'indifference' to its indicators, further studies are needed to identify the minimal set of tools necessary to extract g, and to test also non-cognitive variables as measures of δ. From the clinical perspective, general intelligence seems to influence MND presence and severity more than domain specific cognitive abilities. Giving δ 'blindness' to etiology, its association with biomarkers and contribution to differential diagnosis might be limited. Classical neuropsychological approaches based on patterns of performances at cognitive tests remained fundamental for differential diagnosis.

An Overview of Anthropogenic Actions as Drivers for Emerging and Re-Emerging Zoonotic Diseases

Population growth and industrialization have led to a race for greater food and supply productivity. As a result, the occupation and population of forest areas, contact with wildlife and their respective parasites and vectors, the trafficking and consumption of wildlife, the pollution of water sources, and the accumulation of waste occur more frequently. Concurrently, the agricultural and livestock production for human consumption has accelerated, often in a disorderly way, leading to the deforestation of areas that are essential for the planet's climatic and ecological balance. The effects of human actions on other ecosystems such as the marine ecosystem cause equally serious damage, such as the pollution of this habitat, and the reduction of the supply of fish and other animals, causing the coastal population to move to the continent. The sum of these factors leads to an increase in the demands such as housing, basic sanitation, and medical assistance, making these populations underserved and vulnerable to the effects of global warming and to the emergence of emerging and re-emerging diseases. In this article, we discuss the anthropic actions such as climate changes, urbanization, deforestation, the trafficking and eating of wild animals, as well as unsustainable agricultural intensification which are drivers for emerging and re-emerging of zoonotic pathogens such as viral (Ebola virus, hantaviruses, Hendravirus, Nipah virus, rabies, and severe acute respiratory syndrome coronavirus disease-2), bacterial (leptospirosis, Lyme borreliosis, and tuberculosis), parasitic (leishmaniasis) and fungal pathogens, which pose a substantial threat to the global community. Finally, we shed light on the urgent demand for the implementation of the One Health concept as a collaborative global approach to raise awareness and educate people about the science behind and the battle against zoonotic pathogens to mitigate the threat for both humans and animals.

Fluid intelligence and naturalistic task impairments after focal brain lesions

Classical executive tasks, such as Wisconsin card-sorting and verbal fluency, are widely used as tests of frontal lobe control functions. Since the pioneering work of Shallice and Burgess (1991), it has been known that complex, naturalistic tasks can capture deficits that are missed in these classical tests. Matching this finding, deficits in several classical tasks are predicted by loss of fluid intelligence, linked to damage in a specific cortical "multiple-demand" (MD) network, while deficits in a more naturalistic task are not. To expand on these previous results, we examined the effect of focal brain lesions on three new tests-a modification of the previously-used Hotel task, a new test of task switching after extended delays, and a test of decision-making in imagined real-life scenarios. As potential predictors of impairment we measured volume of damage to a priori MD and default mode (DMN) networks, as well as cortical damage outside these networks. Deficits in the three new tasks were substantial, but were not explained by loss of fluid intelligence, or by volume of damage to either MD or DMN networks. Instead, deficits were associated with diverse lesions, and not strongly correlated with one another. The results confirm that naturalistic tasks capture cognitive deficits beyond those measured by fluid intelligence. We suggest, however, that these deficits may not arise from specific control operations required by complex behaviour. Instead, like everyday activities, complex tasks combine a rich variety of interacting cognitive components, bringing many opportunities for processing to be disturbed.

Neuropsychological spectrum in early PD: Insights from controlled and automatic behavioural regulation

Initial changes in Parkinson's disease (PD) are marked by loss of automatic movements and decline of some cognitive functions. Yet, the exact profile and extent of cognitive impairments in early stages of PD as well as their mechanisms related to automatic motor dysfunction remain unclear. Our objective was to examine the neuropsychological changes in early PD and their association to automatic and controlled modes of behavioural control. Significant relationships between early PD and cognitive dysfunction in set-shifting, abstraction ability/concept formation, processing speed, visuospatial/constructional abilities and verbal-visual memory was found. We also noted that tests with a strong effortful and controlled component were similarly affected as automatic tests by early PD, particularly those testing verbal memory, processing speed and visuospatial/constructional functions. Our findings indicate that initial stages of PD sets constraints over most of the cognitive domains normally assessed and are not easily explained in terms of either automatic or controlled mechanisms, as both appear similarly altered in early PD.

Letter and category Fluency Test in Spanish-Speaking Children with Neurodevelopmental Disorders

Introduction

Verbal fluency test is a short psychometric test, which is sensitive to verbal ability and executive control impairment. We did not find studies that analyze verbal fluency in relation to the neurodevelopmental disorders in Spanish-speaking children with letters P-M. Our objective was to analyze the verbal fluency of Spanish-speaking children with neurodevelopmental disorders.

Method

We carried out a retrospective cross-sectional study to analyze the performance of children who had undergone a neuropsychological assessment.

Results

We included 164 patients. There were 55 (33.54%) patients with low intellectual performance (LIP), 19 (11.59%) patients with dyslexia , and 90 (54.88%) patients had an ADHD. Patients with LIP showed lower phonological fluency than patients with ADHD. As for semantic fluidity, differences were observed between patients with LIP and ADHD and also between LIP and dyslexia. The probability of having LIP was 9.6 times greater when somebody had a scale score lower than 7 in the PF task and it was 16.7 times greater when the scale score was lower than 7 in the SF task.

Conclusions

There was a direct relationship between FSIQ and the performance in verbal fluency test, which is a brief and effective neuropsychological test in revealing deficits in executive functions, verbal abilities, and LIP.

Trajectories of verbal fluency and executive functions in multilingual and monolingual children and adults: A cross-sectional study

The development of verbal fluency is associated with the maturation of executive function skills, such as the ability to inhibit irrelevant information, shift between tasks, and hold information in working memory. Some evidence suggests that multilinguistic upbringing may underpin disadvantages in verbal fluency and lexical retrieval, but can also afford executive function advantages beyond the language system including possible beneficial effects in older age. This study examined the relationship between verbal fluency and executive function in 324 individuals across the lifespan by assessing the developmental trajectories of English monolingual and multilingual children aged 7–15 years (N = 154) and adults from 18 to 80 years old (N = 170). The childhood data indicated patterns of improvement in verbal fluency and executive function skills as a function of age. Multilingual and monolingual children had comparable developmental trajectories in all linguistic and non-linguistic measures used in the study with the exception of planning, for which monolingual children showed a steeper improvement over the studied age range relative to multilingual children. For adults, monolinguals and multilingual participants had comparable performance on all measures with the exception of nonverbal inhibitory control and response times on the Tower of London task: monolinguals showed a steeper decline associated with age. Exploratory factor analysis indicated that verbal fluency was associated with working memory and fluid intelligence in monolingual participants but not in multilinguals. These findings raise the possibility that early acquisition of an additional language may impact on the development of the functional architecture serving high-level human cognition.

Color-dependent changes in humans during a verbal fluency task under colored light exposure assessed by SPA-fNIRS

Light evokes robust visual and nonvisual physiological and psychological effects in humans, such as emotional and behavioral responses, as well as changes in cognitive brain activity and performance. The aim of this study was to investigate how colored light exposure (CLE) and a verbal fluency task (VFT) interact and affect cerebral hemodynamics, oxygenation, and systemic physiology as determined by systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). 32 healthy adults (17 female, 15 male, age: 25.5 ± 4.3 years) were exposed to blue and red light for 9 min while performing a VFT. Before and after the CLE, subjects were in darkness. We found that this long-term CLE-VFT paradigm elicited distinct changes in the prefrontal cortex and in most systemic physiological parameters. The subjects' performance depended significantly on the type of VFT and the sex of the subject. Compared to red light, blue evoked stronger responses in cerebral hemodynamics and oxygenation in the visual cortex. Color-dependent changes were evident in the recovery phase of several systemic physiological parameters. This study showed that the CLE has effects that endure at least 15 min after cessation of the CLE. This underlines the importance of considering the persistent influence of colored light on brain function, cognition, and systemic physiology in everyday life.

Effectiveness of sorting tests for detecting cognitive decline in older adults with dementia and other common neurodegenerative disorders: A meta-analysis

The demand for simple, accurate and time-efficient screens to detect cognitive decline at point-of-care is increasing. Sorting tests are often used to detect the 'executive' deficits that are commonly associated with behavioural-variant frontotemporal dementia (bvFTD), but their potential for use as a cognitive screen with older adults is unclear. A comprehensive search of four databases identified 142 studies that compared the sorting test performance (e.g. WCST, DKEFS-ST) of adults with a common neurodegenerative disorder (e.g. Alzheimer's disease, vascular dementia, bvFTD, Parkinson's disease) and cognitively-healthy controls. Hedges' g effect sizes were used to compare the groups on five common test scores (Category, Total, Perseveration, Error, Description). The neurodegenerative disorders (combined) showed large deficits on all scores (g -1.0 to -1.3), with dementia (combined subtypes) performing more poorly (g -1.2 to -2.1), although bvFTD was not disproportionately worse than the other dementias. Overall, sorting tests detected the cognitive impairments caused by common neurodegenerative disorders, especially dementia, highlighting their potential suitability as a cognitive screen for older adults.

Which cognitive functions subserve clustering and switching in category fluency? Generalisations from an extended set of semantic categories using linear mixed-effects modelling

Clustering and switching are hypothesised to reflect the automatic and controlled components in category fluency, respectively, but how they are associated with cognitive functions has not been fully elucidated, due to several uncertainties. (1) The conventional scoring method that segregates responses by semantic categories could not optimally dissociate the automatic and controlled components. (2) The temporal structure of individual responses, as characterised by mean retrieval time (MRT) and mean switching time (MST), has seldom been analysed alongside the more well-studied variables, cluster size (CS) and number of switches (NS). (3) Most studies examined only one to a few semantic categories, raising concerns of generalisability. This study built upon a distance-based automatic clustering procedure, referred to as temporal-semantic distance procedure, to thoroughly characterise the category fluency performance. Linear mixed-effects (LME) modelling was applied to re-examine the differential associations of clustering and switching with cognitive functions with a sample of 80 university students. Our results revealed that although lexical retrieval speed (LRS) is clearly the determining factor for effective clustering and switching, matrix reasoning and processing speed also have significant roles to play, possibly in the processes of identifying and validating the semantic relationships. Interestingly, total fluency score was accurately predicted by the four clustering/switching indices alone; including the cognitive variables did not significantly improve the prediction. These findings underline the importance of the clustering and switching indices in explaining the category fluency performance and the cognitive demands in category fluency.

COVID-19, an opportunity to reevaluate the correlation between long-term effects of anthropogenic pollutants on viral epidemic/pandemic events and prevalence

Occupational, residential, dietary and environmental exposures to mixtures of synthetic anthropogenic chemicals after World War II have a strong relationship with the increase of chronic diseases, health cost and environmental pollution. The link between environment and immunity is particularly intriguing as it is known that chemicals and drugs can cause immunotoxicity (e.g., allergies and autoimmune diseases). In this review, we emphasize the relationship between long-term exposure to xenobiotic mixtures and immune deficiency inherent to chronic diseases and epidemics/pandemics. We also address the immunotoxicologic risk of vulnerable groups, taking into account biochemical and biophysical properties of SARS-CoV-2 and its immunopathological implications. We particularly underline the common mechanisms by which xenobiotics and SARS-CoV-2 act at the cellular and molecular level. We discuss how long-term exposure to thousand chemicals in mixtures, mostly fossil fuel derivatives, exposure toparticle matters, metals, ultraviolet (UV)–B radiation, ionizing radiation and lifestyle contribute to immunodeficiency observed in the contemporary pandemic, such as COVID-19, and thus threaten global public health, human prosperity and achievements, and global economy. Finally, we propose metrics which are needed to address the diverse health effects of anthropogenic COVID-19 crisis at present and those required to prevent similar future pandemics.

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Developmental exposure to environmental factors can disrupt the immune system.

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Long-term low-dose exposure to chemical mixtures is linked to imunodeficiency

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Immunodeficiency contributes to chronic diseases and the current Covid-19 pandemics.

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Environmental chemicals and microorganisms share similar molecular pathomechanisms (AhR pathway).

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Understanding the underlying pathomechanisms helps to improve public health.

The relationship between executive functions and fluid intelligence in multiple sclerosis

BACKGROUND & OBJECTIVE

Deficits in cognitive functions dependent upon the integrity of the prefrontal cortex have been described in Multiple Sclerosis (MS). In a series of studies we have shown that fluid intelligence (g) is a substantial contributor to frontal deficits and that, for some classical "executive" tasks, frontal deficits were entirely explained by g. However, for another group of frontal tasks deficits remained once g was introduced as a covariate. This second set of tests included multitasking and theory of mind tasks. In the present study, we aimed at determining the role of fluid intelligence in frontal deficits seen in patients with MS.

METHODS

A group of patients with Relapsing Remitting MS (n = 36) and a group of control subjects (n = 42) were assessed with a battery of classical executive tests (which included the Wisconsin Card Sorting Test, Verbal Fluency, and Trail Making Test B), a multitasking test, a theory of mind test and a fluid intelligence test.

RESULTS

MS patients showed significant deficits in the fluid intelligence task. We found differences between patients and control subjects in all tests except for the multitasking test. The differences in the classical executive tests became non-significant once fluid intelligence was introduced as a covariate, but differences in theory of mind remained.

CONCLUSIONS

The present results suggest that fluid intelligence can be affected in MS and that this impairment can play a role in the executive deficits described in MS.

Sex Differences in Verbal Fluency Among Young Adults

Verbal fluency tasks have been used as tools to measure various cognitive processes, such as executive functions, memory, and language. Sex differences in verbal fluency performance have been mostly investigated in population studies. Little of this research has focused on young adults. The goal of this study was to assess the impact of sex and task category on word production and verbal strategies (i.e., cluster size and switches) in young adults. The phonemic (letter “k”, letter “f”) and semantic (animals, fruits, sharp objects) fluency measures were used. Men and women were compared in terms of the number of produced words and the use of verbal strategies (number of switches and mean cluster size controlled for produced words). Results revealed subtle sex differences in verbal fluency in young adults. Men performed slightly better in semantic fluency, producing more words, while there were no sex differences in verbal strategies. There were also no sex differences in word production and verbal strategies in the phonemic fluency tasks. Furthermore, there were differences in the number of produced words, mean cluster sizes, and switches between semantic tasks as well as between phonemic tasks. These results can be interpreted in the context of potential differences in mental lexicon and social roles. Moreover, our results suggest that assessment of verbal strategies and overall word production may be important in the context of sex differences in verbal fluency among young adults as well as in neuropsychological diagnosis

Executive functions predict literacy and mathematics achievements: The unique contribution of cognitive flexibility in grades 2, 4, and 6

Research has shown that cognitive flexibility plays a critical role in students' learning and academic achievement. However, the unique contribution of cognitive flexibility to academic achievement across schooling is not fully understood. Thus, this study tested whether cognitive flexibility explained a significant amount of variance in academic achievement (i.e., literacy and mathematics outcomes) across Grades 2, 4, and 6, above and beyond fluid intelligence, inhibitory control, working memory, attention, and planning. The sample included 243 second graders, 284 fourth graders, and 203 sixth graders. For Grades 4 and 6, we found that better performance on the flexibility score was associated with better academic outcomes after controlling for fluid intelligence, attention, inhibitory control, working memory, and planning. This effect was not observed for Grade 2. Our findings showed that cognitive flexibility is a key component for school achievement, particularly for older students.

Verbal Fluency Test in Children with Neurodevelopmental Disorders

Background  The verbal fluency task is a widely used psychometric test to account for cognitive functions, particularly, verbal and executive functions. Being an easy and fast test to administer, it is a good neuropsychological tool in low technology environments. Our objective was to analyze the performance in verbal fluency of Spanish-speaking children with neurodevelopmental disorders. Methods  We performed a retrospective cross-sectional study to analyze the performance of children who had undergone a verbal fluency test in a neuropsychological assessment. Results  We included 115 participants. There were 41 (35.65%) participants with low intellectual performance (LIP), 63 (54.78%) with attention deficit hyperactive disorder (ADHD), and 11(9.57%) participants with dyslexia. Participants with LIP showed lower phonological and semantic fluency scores than participants with ADHD, and a lower performance in semantic fluency than the dyslexia group. The probability of having LIP was 6.12 times greater when somebody had a scale score lower than 7 in the phonological task and it was 7.9 times greater when the scale score was lower than 7 in the semantic task. Conclusion  There was a direct relationship between Full Scale Intelligence Quotient and verbal fluency test performance, the latter being a brief and effective neuropsychological test that can reveal deficit not only in executive functions and verbal abilities but also detect LIP.

A Meta-Analysis of Relationships between Measures of Wisconsin Card Sorting and Intelligence

The Wisconsin Card Sorting Test (WCST) represents a widely utilized neuropsychological assessment technique for executive function. This meta-analysis examined the discriminant validity of the WCST for the assessment of mental shifting, considered as an essential subcomponent of executive functioning, against traditional psychometric intelligence tests. A systematic search was conducted, resulting in 72 neuropsychological samples for the meta-analysis of relationships between WCST scores and a variety of intelligence quotient (IQ) domains. The study revealed low to medium-sized correlations with IQ domains across all WCST scores that could be investigated. Verbal/crystallized IQ and performance/fluid IQ were indistinguishably associated with WCST scores. To conclude, the WCST assesses cognitive functions that might be partially separable from common conceptualizations of intelligence. More vigorous initiatives to validate putative indicators of executive function against intelligence are required.

Response initiation and inhibition and the relationship with fluid intelligence across the adult lifespan

Background

Cognitive processes associated with frontal lobe functioning are often termed “executive functions.” Two such processes are initiation and inhibition or the starting and stopping of responses. It has recently been claimed dysfunction of executive abilities can be explained by a single measure of fluid intelligence. Here, we test this claim, specifically for the executive abilities of response initiation and inhibition, across the healthy lifespan.

Method

In a cohort of 336 healthy adults (18–89 years), initiation and inhibition were assessed with the Hayling test, Stroop test, and phonemic and semantic verbal fluency. All participants also completed a measure of fluid intelligence. The relationship between fluid intelligence and executive measures was explored across the lifespan using a continuous approach. Mediation models were computed to assess whether age-related decline across the four initiation/inhibition tasks could be fully explained by a single measure of fluid intelligence.

Results

Age was negatively correlated with response initiation/inhibition and fluid intelligence. The mediation analyses identified only partial mediation of fluid intelligence for age and Hayling performance. By contrast, fluid intelligence did not mediate performance on the Stroop test or phonemic and semantic verbal fluency.

Conclusions

Response initiation/inhibition are not able to be explained by fluid intelligence. The results support a multifactorial theory of executive functions and provide evidence for the inclusion of multiple specific executive measures in a thorough neuropsychological assessment of age-related cognitive decline.

Executive Processes Underpin the Bilingual Advantage on Phonemic Fluency: Evidence From Analyses of Switching and Clustering

Bilinguals often show a disadvantage in lexical access on verbal fluency tasks wherein the criteria require the production of words from semantic categories. However, the pattern is more heterogeneous for letter (phonemic) fluency wherein the task is to produce words beginning with a given letter. Here, bilinguals often outperform monolinguals. One explanation for this is that phonemic fluency, as compared with semantic fluency, is more greatly underpinned by executive processes and that bilinguals exhibit better performance on phonemic fluency due to better executive functions. In this study, we re-analyzed phonemic fluency data from the Betula study, scoring outputs according to two measures that purportedly reflect executive processes: clustering and switching. Consistent with the notion that bilinguals have superior executive processes and that these can be used to offset a bilingual disadvantage in verbal fluency, bilinguals (35-65 years at baseline) demonstrated greater switching and clustering throughout the 15-year study period.

Neurocognitive mechanisms of theory of mind impairment in neurodegeneration: a transdiagnostic approach

Much of human interaction is predicated upon our innate capacity to infer the thoughts, beliefs, emotions, and perspectives of others, in short, to possess a "theory of mind" (ToM). While the term has evolved considerably since its inception, ToM encompasses our unique ability to apprehend the mental states of others, enabling us to anticipate and predict subsequent behavior. From a developmental perspective, ToM has been a topic of keen research interest, with numerous studies seeking to explicate the origins of this fundamental capacity and its disruption in developmental disorders such as autism. The study of ToM at the opposite end of the lifespan, however, is paradoxically new born, emerging as a topic of interest in its own right comparatively recently. Here, we consider the unique insights afforded by studying ToM capacity in neurodegenerative disorders. Arguing from a novel, transdiagnostic perspective, we consider how ToM vulnerability reflects the progressive degradation of neural circuits specialized for an array of higher-order cognitive processes. This mechanistic approach enables us to consider the common and unique neurocognitive mechanisms that underpin ToM dysfunction across neurodegenerative disorders and for the first time examine its relation to behavioral disturbances across social, intimate, legal, and criminal settings. As such, we aim to provide a comprehensive overview of ToM research in neurodegeneration, the resultant challenges for family members, clinicians, and the legal profession, and future directions worthy of exploration.

Affective theory of mind in Parkinson's disease: the effect of cognitive performance

PURPOSE

Among other non-motor symptoms, theory of mind (ToM), the ability to recognize, understand and infer others' mental states, beliefs, intents and wishes, has been shown to deteriorate during the course of Parkinson's disease (PD). It has been speculated that ToM impairments could be related to cognitive deficits in PD. However, the current state of literature suggests that there is heterogeneity regarding the involvement of cognitive functioning in the relationship of PD and ToM. The study aimed to measure affective ToM abilities and cognitive performance in a sample of PD patients, to explore the link between affective ToM abilities and cognitive status, and to examine the impact of PD on affective ToM through the mediator effect of cognitive performance.

PATIENTS AND METHODS

Sixty-five patients diagnosed with idiopathic PD and 51 healthy controls matched for age, gender and educational level completed a visual affective ToM task (Reading the Mind in the Eyes - RMET), cognitive performance was evaluated with Montreal Cognitive Assessment, and psychiatric symptoms were measured with BPRS-E (Brief Psychiatric Rating Scale).

RESULTS

Affective ToM abilities were preserved in early PD patients, declining as the disease progressed. Deficits in cognitive functioning predicted deficiencies in affective ToM. Although attention (AT), executive functions (EF) and visuospatial abilities (VSA) together mediated the relationship between PD and affective ToM, only VSA impairment had a specific negative impact on affective ToM. Moreover, 41% of the total effect of attention and executive functions on affective ToM was mediated by visuospatial skills.

CONCLUSION

Cognitive performance may have an impact on the relationship between PD and affective ToM through the involvement of VSA. The influence of AT and EF in this relationship appears to be also exerted by PD patients' VSA.

Emotion-Specific Affective Theory of Mind Impairment in Parkinson's Disease

The neuropathology of Parkinson’s disease (PD) involves the frontal-subcortical circuit, an area responsible for processing affective theory of mind (ToM). Patients with PD are expected to experience deficits in the affective ToM. This study aims to investigate whether the ability to infer emotion in others is affected in either young-onset Parkinson’s disease (YOPD) or middle-onset PD (MOPD) patients and to test whether the impairments in affective ToM are associated with the motor symptoms. The affective ToM, global mental abilities, and clinical symptoms were assessed in a total of 107 MOPD, 30 YOPD, and 30 normal controls (NCs). The MOPD patients exhibited deficits in affective ToM to the negative and neutral valences, when compared to the participants in the NCs and YOPD group. By conducting gender-stratified analysis, the deficits in affective ToM was only found in female participants. After adjusting for demographic variables, the multiple linear regression model revealed that affective ToM predicted motor symptoms, especially in female MOPD patients. The present study may aid in the development of medical care programs by advocating for a more comprehensive therapeutic plan that includes continuous disease progression monitoring and social skills training for female MOPD patients or their caregivers.

Cognitive profile of non-demented Parkinson's disease: Meta-analysis of domain and sex-specific deficits

INTRODUCTION

Better awareness of the cognitive domains affected in non-demented Parkinson's Disease (PD) should improve understanding of cognitive disease mechanisms. A complete understanding of the cognitive areas impaired in non-demented PD is hindered because most studies use small clinical samples without comparison to healthy controls. This meta-analysis examined cumulative evidence across studies to determine if there were impairments in non-demented PD in the three cognitive domains thought to be most widely affected in PD: frontal executive, visuospatial, and verbal memory. Because there are well-documented sex differences in PD, a second objective was to explore sex differences in these findings.

METHODS

MEDLINE, EMBASE and PsycINFO databases were searched (1988-March 2017). Random effects models were used to compute and compare effect sizes of differences between PD patients and controls within cognitive domains. Sex differences in effect sizes were also examined in these comparisons. Moderating factors including age, disease duration, motor symptom severity, levodopa dosage, and depression were examined through meta-regression.

RESULTS

PD patients showed deficits of moderate effect sizes in all three cognitive domains relative to controls. Significant sex differences were observed only for frontal executive abilities, with male PD patients showing greater deficits than female PD patients relative to controls. No moderators of effect sizes were identified in the domain specific overall or sex-segregated meta-analyses.

CONCLUSIONS

Results indicate that non-demented PD patients have deficits of moderate magnitude in frontal executive, verbal memory, and visuospatial abilities. Our findings of greater frontal executive deficits in males warrant further confirmation.

Connectivity patterns in cognitive control networks predict naturalistic multitasking ability

Multitasking is a fundamental aspect of everyday life activities. To achieve a complex, multi-component goal, the tasks must be subdivided into sub-tasks and component steps, a critical function of prefrontal networks. The prefrontal cortex is considered to be organized in a cascade of executive processes from the sensorimotor to anterior prefrontal cortex, which includes execution of specific goal-directed action, to encoding and maintaining task rules, and finally monitoring distal goals. In the current study, we used a virtual multitasking paradigm to tap into real-world performance and relate it to each individual's resting-state functional connectivity in fMRI. While did not find any correlation between global connectivity of any of the major networks with multitasking ability, global connectivity of the lateral prefrontal cortex (LPFC) was predictive of multitasking ability. Further analysis showed that multivariate connectivity patterns within the sensorimotor network (SMN), and between-network connectivity of the frontoparietal network (FPN) and dorsal attention network (DAN), predicted individual multitasking ability and could be generalized to novel individuals. Together, these results support previous research that prefrontal networks underlie multitasking abilities and show that connectivity patterns in the cascade of prefrontal networks may explain individual differences in performance.

Genetic and Environmental Influences on Language Ability in Older Adults: Findings from the Older Australian Twins Study

We used a sub-sample from the Older Australian Twins Study to estimate the heritability of performance on three tests of language ability: Boston Naming Test (BNT), Letter/Phonemic Fluency (FAS) and Category/Semantic Fluency (CFT) Tests. After adjusting for age, sex, education, mood, and global cognition (GC), heritability estimates obtained for the three tests were 0.35, 0.59, and 0.20, respectively. Multivariate analyses showed that the genetic correlation were high for BNT and CFT (0.61), but low for BNT and FAS (0.17), and for FAS and CFT (0.28). Genetic modelling with Cholesky decomposition indicated that the covariation between the three measures could be explained by a common genetic factor. Environmental correlations between the language ability measures were low, and there were considerable specific environmental influences for each measure. Future longitudinal studies with language performance and neuroimaging data can further our understanding of genetic and environmental factors involved in the process of cognitive aging.

Decision-making competence in younger and older adults: which cognitive abilities contribute to the application of decision rules?

Older adults perform worse than younger adults when applying decision rules to choose between options that vary along multiple attributes. Although previous studies have shown that general fluid cognitive abilities contribute to the accurate application of decision rules, relatively little is known about which specific cognitive abilities play the most important role. We examined the independent roles of working memory, verbal fluency, semantic knowledge, and components of executive functioning. We found that age-related decline in applying decision rules was statistically mediated by age-related decline in working memory and verbal fluency. Our results have implications for theories of aging and decision-making.

The relationship between executive functions and fluid intelligence in euthymic Bipolar Disorder patients

Distinct cognitive deficits have been described in Bipolar disorder (BD), including executive impairments, commonly attributed to frontal dysfunction. However, recent attention has been paid to the heterogeneity of cognitive functioning in this population, suggesting that the executive deficits observed in BD might be due to a loss in fluid intelligence (g). Following our previous line of investigation in multiple neurological and psychiatric conditions we aimed at determining the role of g in frontal deficits in BD. Euthymic BD patients (n = 51) and healthy controls (n = 37) were assessed with Wisconsin Card Sorting Test (WCST), Verbal Fluency, Trail Making Test B (TMTB), a multitasking test, and a theory of mind test. A general cognitive battery was used to derive a measure of g. As in other neuropsychiatric conditions, significant patient-control differences in WCST, Verbal Fluency and TMTB were removed when g was introduced as a covariate. Deficits remained significant in the multitasking test. We suggest that neuropsychological assessment in BD should include tests of general intelligence, together with one or more specific tasks that allow for the assessment of residual frontal deficits, putatively associated with anterior frontal functioning.

Resting state fMRI correlates of Theory of Mind impairment in amyotrophic lateral sclerosis

Theory of Mind (ToM), the ability to recognize thoughts and emotions of another, may be one of the cognitive domains affected in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease now recognized as a multi-system disorder. The present study aimed to identify early dysfunctions of brain resting state functional magnetic resonance imaging (RS-fMRI) networks in a group of ALS patients longitudinally explored for impairment of "cognitive" and "affective" ToM subcomponents. RS-fMRI connectivity was investigated in a group of 21 patients with ALS (i.e., 9 with bulbar-onset or ALS-B and 12 with limb-onset or ALS-L) in early stages of disease and 15 healthy controls (HCs). The same subjects were assessed, at baseline and after six months, for neuropsychological performances, including cognitive and affective ToM and multi-domain cognitive functions. The RS-fMRI study showed a decreased connectivity in frontotemporal areas within the main cognitive resting state networks, including the default mode (DMN), the right and left fronto-parietal (R-, L-FPN), and the salience (SLN) networks, in the entire ALS group. As exploratory results, comparing the ALS-B subgroup to the ALS-L one, we revealed a widespread decrease of RS-fMRI signals in the left middle frontal gyrus for L-FPN and SLN and in the left superior frontal gyrus for SLN. At baseline, no ToM or other cognitive abnormalities were reported in the entire group of ALS patients compared to HCs, although, after six months, the ALS-B subset exhibited a significant impairment of both affective and cognitive ToM subcomponents, whereas the ALS-L group showed significant impairment of the cognitive subcomponent alone. Our findings provide original evidence of the deficit of both ToM subcomponents during the ALS course, supporting the hypothesis of a biologically more aggressive character of ALS-B. Moreover, early RS-fMRI abnormalities in cognitive networks may underlie and precede the clinical appearance of ToM alterations in ALS.

Theory of Mind and Its Neuropsychological and Quality of Life Correlates in the Early Stages of Amyotrophic Lateral Sclerosis

This study aims to explore the potential impairment of Theory of Mind (ToM; i.e., the ability to represent cognitive and affective mental states to both self and others) and the clinical, neuropsychological and Quality of Life (QoL) correlates of these cognitive abnormalities in the early stages of amyotrophic lateral sclerosis (ALS), a multisystem neurodegenerative disease recently recognized as a part of the same clinical and pathological spectrum of frontotemporal lobar degeneration. Twenty-two consecutive, cognitively intact ALS patients, and 15 healthy controls, underwent assessment of executive, verbal comprehension, visuospatial, behavioral, and QoL measures, as well as of the ToM abilities by Emotion Attribution Task (EAT), Advanced Test of ToM (ATT), and Eyes Task (ET). ALS patients obtained significantly lower scores than controls on EAT and ET. No significant difference was found between the two groups on ATT. As regard to type of ALS onset, patients with bulbar onset performed worse than those with spinal onset on ET. Correlation analysis revealed that EAT and ET were positively correlated with education, memory prose, visuo-spatial performances, and “Mental Health” scores among QoL items. Our results suggest that not only “cognitive” but also “affective” subcomponents of ToM may be impaired in the early stages of ALS, with significant linkage to disease onset and dysfunctions of less executively demanding conditions, causing potential impact on patients’ “Mental Health.”

Age-related differences in the predictive ability of executive functions for intelligence

Abstract. The Executive Functions Module of the Neuropsychological Assessment Battery (NAB) and the Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV) were used to investigate age-related differences in the predictability of intelligence with executive functions. The NAB subtests age and sex better predicted the WAIS-IV index scales and the Full Scale IQ in the older than in the younger age group, with total variance explained up to 75 % in 60- to 88-year-olds and up to 46 % in 18- to 59-year-olds. The NAB subtests Categories and Word Generation were most frequently included, whereas Letter Fluency was least frequently included in the best-fitting models of WAIS-IV prediction. Mazes predicted better in the younger age group, whereas Judgment predicted better in the older age group.

Effects of age, education, and gender on verbal fluency in healthy adult Arabic-speakers in Egypt

The objective of this study is to establish the effects of age, gender, and education and to provide preliminary normative data for letter and category fluency tasks in the Egyptian Arabic-speaking population. We evaluated 139 cognitively healthy volunteers aged 20-93 by adapting the letter and category verbal fluency tasks for the Egyptian population. On the letter fluency task, mean number of words generated in one-minute beginning with the Arabic letter "Sheen" (pronounced "sh") was 8.14 words per minute (SD = 3.25). Letter fluency was significantly influenced by education. On category fluency tasks, mean number of animal names generated in one minute was 14.63 words (SD = 5.28). Category fluency was significantly influenced by age and education. We were able identify that age significantly affects category fluency while education significantly affected both letter and category fluency. We were also able to provide preliminary normative data for both tasks in the Egyptian population.

In two minds: executive functioning versus theory of mind in behavioural variant frontotemporal dementia

BACKGROUND

The relationship of executive function (EF) and theory of mind (ToM) deficits in neurodegeneration is still debated. There is contradicting evidence as to whether these cognitive processes are overlapping or distinct, which has clear clinical relevance for the evaluation of their associated clinical symptoms.

AIM

To investigate the relationship of EF and ToM deficits via a data-driven approach in a large sample of patients with behavioural variant frontotemporal dementia (bvFTD).

METHODS

Data of 46 patients with bvFTD were employed in a hierarchical cluster analysis to determine the similarity of variance between different EF measures (verbal abstraction, verbal initiation, motor programming, sensitivity to interference, inhibitory control, visual abstraction, flexibility, working memory/attention) and ToM (faux pas).

RESULTS

Overall results showed that EF measures were clustered separately from the ToM measure. A post hoc analysis revealed a more complex picture where selected ToM subcomponents (empathy; intention) showed a relationship to specific EF measures (verbal abstraction; working memory/attention), whereas the remaining EF and ToM subcomponents were separate.

CONCLUSIONS

Taken together, these findings suggest that EF and ToM are distinct components; however, ToM empathy and intention subcomponents might share some functions with specific EF processes. This has important implications for guiding diagnostic assessment of these deficits in clinical conditions.

Fluid intelligence and executive functioning more alike than different?

OBJECTIVE

Fluid intelligence (Gf) has been related to executive functioning (EF) in previous studies, and it is also known to be correlated with crystallized intelligence (Gc). The present study includes representative measures of Gf, Gc, and EF frequently used in clinical practice to examine this Gf-EF relation. It is hypothesised that the Gf-EF relation is higher than the Gc-EF relation, and that working memory in particular (as a measure of EF) shows a high contribution to this relation.

METHOD

Confirmatory factor analysis was performed on a mixed neuropsychiatric and non-clinical sample consisting of 188 participants, using the Kaufman Adolescent and Adult Intelligence Test, and three executive tasks of the Cambridge Neuropsychological Test Automated Battery, covering working memory, planning skills, and set shifting.

RESULTS

The model fitted the data well [χ²(24)=35.25, p=0.07, RMSEA=0.050]. A very high correlation between Gf and EF was found (0.91), with working memory being the most profound indicator. A moderate to high correlation between Gc and EF was present. Current results are consistent with findings of a strong relation between Gf and working memory.

CONCLUSION

Gf and EF are highly correlated. Gf dysfunction in neuropsychiatric patients warrants further EF examination and vice versa. It is discussed that results confirm the need to distinguish between specific versus general fluid/executive functioning, the latter being more involved when task complexity and novelty increase. This distinction can provide a more refined differential diagnosis and improve neuropsychiatric treatment indication.

Inter-individual cognitive variability in children with Asperger's syndrome

Multiple studies have tried to establish the distinctive profile of individuals with Asperger's syndrome (AS). However, recent reports suggest that adults with AS feature heterogeneous cognitive profiles. The present study explores inter-individual variability in children with AS through group comparison and multiple case series analysis. All participants completed an extended battery including measures of fluid and crystallized intelligence, executive functions, theory of mind, and classical neuropsychological tests. Significant group differences were found in theory of mind and other domains related to global information processing. However, the AS group showed high inter-individual variability (both sub- and supra-normal performance) on most cognitive tasks. Furthermore, high fluid intelligence correlated with less general cognitive impairment, high cognitive flexibility, and speed of motor processing. In light of these findings, we propose that children with AS are characterized by a distinct, uneven pattern of cognitive strengths and weaknesses.

What do verbal fluency tasks measure? Predictors of verbal fluency performance in older adults

This study examined the contributions of verbal ability and executive control to verbal fluency performance in older adults (n = 82). Verbal fluency was assessed in letter and category fluency tasks, and performance on these tasks was related to indicators of vocabulary size, lexical access speed, updating, and inhibition ability. In regression analyses the number of words produced in both fluency tasks was predicted by updating ability, and the speed of the first response was predicted by vocabulary size and, for category fluency only, lexical access speed. These results highlight the hybrid character of both fluency tasks, which may limit their usefulness for research and clinical purposes.

The relationship between executive functions and fluid intelligence in schizophrenia

An enduring question is unity vs. separability of executive deficits resulting from impaired frontal lobe function. In previous studies, we have asked how executive deficits link to a conventional measure of fluid intelligence, obtained either by standard tests of novel problem-solving, or by averaging performance in a battery of novel tasks. For some classical executive tasks, such as the Wisconsin Card Sorting Test (WCST), Verbal Fluency, and Trail Making Test B (TMTB), frontal deficits are entirely explained by fluid intelligence. However, on a second set of executive tasks, including tests of multitasking and decision making, deficits exceed those predicted by fluid intelligence loss. In this paper we discuss how these results shed light on the diverse clinical phenomenology observed in frontal dysfunction, and present new data on a group of 15 schizophrenic patients and 14 controls. Subjects were assessed with a range of executive tests and with a general cognitive battery used to derive a measure of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate. In line with our previous results, significant patient-control differences in classical executive tests were removed when fluid intelligence was introduced as a covariate. However, for tests of multitasking and decision making, deficits remained. We relate our findings to those of previous factor analytic studies describing a single principal component, which accounts for much of the variance of schizophrenic patients' cognitive performance. We propose that this general factor reflects low fluid intelligence capacity, which accounts for much but not all cognitive impairment in this patient group. Partialling out the general effects of fluid intelligence, we propose, may clarify the role of additional, more specific cognitive impairments in conditions such as schizophrenia.

Translation and validation of Chinese version of the problems in everyday living (PEDL) test in patients with mild cognitive impairment

BACKGROUND

Cognitive impairment places older adults at increased risk of functional decline, injuries, and hospitalization. Assessments to determine whether older persons are still capable of meeting the cognitive challenges of everyday living are crucial to ensure their safe and independent living in the community. The present study aims to translate and validate the Chinese version of the Problems in Everyday Living (PEDL) test for use in Chinese population with mild cognitive impairment (MCI).

METHODS

The cultural relevancy and content validity of the Chinese version of PEDL (C-PEDL) was evaluated by a seven-member expert panel. Forty patients with MCI and 40 cognitively healthy participants were recruited to examine the psychometric properties of C-PEDL.

RESULTS

Significant differences in the C-PEDL scores were found between the patients with MCI and the cognitively healthy controls in both educated (F = 9.96, p = 0.003) and illiterate (F = 10.43, p = 0.004) populations. The C-PEDL had excellent test-retest and inter-rater reliabilities, with intraclass correlation coefficient at 0.95 and 0.99 respectively. The internal consistency of C-PEDL was acceptable with Chronbach's α at 0.69. The C-PEDL had moderate correlation with the Mini-Mental State Examination (r = 0.45, p = 0.004) and the Category Verbal Fluency Test (r = 0.40, p = 0.012), and a moderate negative Spearman's correlation with the Global Deteriorating Scale (r = -0.42, p = 0.007).

CONCLUSIONS

The C-PEDL is a valid and reliable test for assessing the everyday problem-solving ability in Chinese older population with MCI.

The structure of cognition: attentional episodes in mind and brain

Cognition is organized in a structured series of attentional episodes, allowing complex problems to be addressed through solution of simpler subproblems. A "multiple-demand" (MD) system of frontal and parietal cortex is active in many different kinds of tasks, and using data from neuroimaging, electrophysiology, neuropsychology, and cognitive studies of intelligence, I propose a core role for MD regions in assembly of the attentional episode. Monkey and human data show dynamic neural coding of attended information across multiple MD regions, with rapid communication within and between regions. Neuropsychological and imaging data link MD function to fluid intelligence, explaining some but not all "executive" deficits after frontal lobe lesions. Cognitive studies link fluid intelligence to goal neglect, and the problem of dividing complex task requirements into focused parts. Like the innate releasing mechanism of ethology, I suggest that construction of the attentional episode provides a core organizational principle for complex, adaptive cognition.

Social brain dysfunctions in patients with Parkinson's disease: a review of theory of mind studies

Human social interaction is essential in daily life and crucial for a promising life, especially in people who suffer from disease. Theory of Mind (ToM) is fundamental in social interaction and is described as the ability to impute the mental states of others in social situations. Studies have proposed that a complex neuroanatomical network that includes the frontal cortex mediates ToM. The primary neuropathology of Parkinson’s disease (PD) involves the frontal-striatal system; therefore, patients with PD are expected to exhibit deficits in ToM. In this review, we summarize the current research with a particular focus on the patterns of impaired ToM, potential mediators of ToM, and the impact of ToM deficits on clinical disability in PD. Further studies to investigate the progression of ToM and its relationship with dementia in subjects in PD are needed.

The effect of cognitive status and visuospatial performance on affective theory of mind in Parkinson's disease

It is now well accepted that theory of mind (ToM) functioning is impaired in Parkinson's disease (PD) patients. However, what remain unknown are the functions that underlie this impairment. It has been suggested that cognitive skills may be key in this area of functioning; however, many of the cognitive tests used to assess this have relied on intact visuospatial abilities. This study aimed to examine whether deficits in ToM were generated by cognitive or visuospatial dysfunction and the mediating effect of visuospatial function on ToM performance. Fifty PD patients (31 male, 19 female; mean age = 66.34 years) and 49 healthy controls (16 male, 33 female; mean age = 67.29 years) completed a ToM task (reading the mind in the eyes) and visuospatial task (line orientation). The results revealed that current cognitive status was a significant predictor for performance on the ToM task, and that 54% of the total effect of cognitive status on ToM was mediated by visuospatial abilities. It was concluded that visuospatial functioning plays an important mediating role for the relationship between executive dysfunction and affective ToM deficits in PD patients, and that visuospatial deficits may directly contribute to the presence of affective ToM difficulties seen in individuals with PD.