Differences between young and older adults in unity and diversity of executive functions

The validity of studying healthy aging with cognitive tests measuring different constructs

A clinically useful characterization of the cognitive aging process requires the development of valid and robust behavioral tests, with an emphasis on explaining and understanding typical inter-individual variability in cognition. Here, using a dataset that includes behavioral scores collected with the National Institute of Health Toolbox Cognition Battery (NIHTB-CB) and other auxiliary tests, we examined (1) the differences between young and old adults across different cognitive domains, (2) the strength of across-subject correlations in behavioral test scores, (3) the consistency of low-dimensional behavioral representations across age using factor analysis, and (4) the accuracy of behavioral scores in predicting participants' age. Our results revealed that (1) elderly females had better verbal episodic memory scores than elderly males, (2) across-subject correlations between behavioral tests varied with age group, (3) although a three-factor model explained the behavioral data in both age groups, some tasks loaded to different factors between the two groups, and (4) age-performance relationship (i.e. a regression model linking age to cognitive scores) in one group cannot be extrapolated to predict age in the other group, indicating an inconsistency in age-performance relationships across groups. These findings suggest that executive function tests might tap into different cognitive processes in different age groups, which might ultimately suggest that a statistically significant between-group difference in test performance might not always reflect differences in the same underlying cognitive processes. Overall, this study calls for more caution when interpreting age-related differences and similarities between age groups with different cognitive abilities even when the same tests are used.

Individual differences in attention control: A meta-analysis and re-analysis of latent variable studies

A meta-analysis and re-analysis of prior latent variable studies was conducted in order to assess whether there is evidence for individual differences in broad attention control abilities. Data from 90 independent samples and over 23,000 participants suggested that most (84.4%) prior studies find evidence for a coherent attention control factor with average factor loadings of .51. This latent attention control factor was related to other cognitive ability factors including working memory, shifting, fluid intelligence, long-term memory, reading comprehension, and processing speed, as well as to self-reports of task-unrelated thoughts and task specific motivation. Further re-analyses and meta-analyses suggest that the results remained largely unchanged when considering various possible measurement issues. Examining the factor structure of attention control suggested evidence for sub-components of attention control (restraining, constraining and sustaining attention) which could be accounted for a by a higher-order factor. Additional re-analyses suggested that attention control represents a broad ability within models of cognitive abilities. Overall, these results provide evidence for attention control abilities as an important individual differences construct.

Individual and Age Differences in Item and Context Memory

We investigated whether individuals who are good at recognizing previously presented items are also good at recognizing the context in which items were presented. We focused specifically on whether the relation between item recognition and context recognition abilities differs in younger and older adults. It has been hypothesized that context memory declines more rapidly in older adults due to an age-related deficit in associative binding or recollection. To test this hypothesis, younger and older adults were asked to remember lists of names and objects, as well as the context (i.e. their size, location, and color) that accompanied those items. Following presentation of each list, recognition tests for items and context were administered. Confirmatory factor analysis (CFA) models analyzing both item and context scores together provided no evidence of separate factors for item and context memory. Instead, the best-fitting model separated performance by item-type, regardless of context, and no differences were found in the structure of these abilities in younger and older adults. These findings are consistent with the limited previous latent variable research on context memory in aging suggesting that there is no context recognition memory ability separable from item memory in younger nor older adults. Instead, individual differences in recognition memory abilities may be specific to the domain of the studied stimulus.

The effect of age on task switching: updated and extended meta-analyses

Cognitive flexibility is one of the crucial abilities for human survival. As people get older, whether their flexibility ability will be affected is one of the core research topics in aging research. Researchers have developed a task-switch paradigm in laboratories to mimic daily-life shifting task-set scenarios. However, the empirical evidence is equivocal. Considering every single study may have a biased sample; therefore, we hoped to combine smaller studies, making them into one extensive investigation, which may help show an actual effect. In the current study, we used two meta-analysis techniques, the Brinley plot (along with the State-trace plot) and conventional meta-analysis, to re-evaluate whether healthy aging influences cognitive flexibility. The results of the Brinley plot analysis showed no evidence of switch-specific age-related impairment as indexed by the local switch cost. Yet, older adults performed more slowly than younger adults across task conditions. The conventional meta-analysis further showed that the currently available findings were heterogenous and exhibited publication bias. Therefore, this study suggests that researchers should interpret their results cautiously while using a task-switching paradigm to address older adults' shifting abilities. More parametric variables must be considered and developed in a task-switching paradigm to enhance its sensitivity and reveal older adults' actual shifting ability.

Shifting as an executive function separate from updating and inhibition in old age: Behavioral and genetic evidence

This study aimed to examine the organization of executive functions (EFs), specifically working memory updating, prepotent response inhibition, and mental-set shifting in old age, with a particular focus on determining whether the shifting function was behaviorally and genetically separated from the other functions. A total of 248 healthy older Chinese individuals participated, and multiple measures of executive functions were collected. Additionally, measures of fluid intelligence were included to explore the varying relationships between the three executive functions and this higher-order cognitive ability. Furthermore, genetic data were gathered and analyzed to investigate the associations between EFs and six candidate single-nucleotide polymorphisms (SNPs) mapped to dopaminergic, serotonergic, or glutamatergic genes. The results indicated that both the three-factor model and the two-factor model, which combined updating and inhibition, demonstrated a good fit. Furthermore, shifting was found to be behaviorally separated from the other two functions, and the correlation between shifting and fluid intelligence was smaller compared to the correlations between updating and inhibition with fluid intelligence. Moreover, the DRD2 SNPs showed significant associations with shifting, rather than with updating and inhibition. These findings provide evidence that shifting is distinct and separate from updating and inhibition, highlighting the diversity of EFs among older adults.

Validity and reliability of a computerized cognitive function evaluation battery (CogEvo) as a screening tool

Aim

The aim of this study was to determine the validity and reliability of cognitive function evaluation battery, CogEvo, a recently developed computerized cognitive function evaluation battery, as a screening tool for decreased cognitive function.

Methods

The study sample comprised 123 (age: 57-97 years) community-dwelling elderly people. They were required to perform five CogEvo tasks and complete two questions-based neuropsychological tests, including the Mini-Mental State Examination, so that the correlations could be analyzed. The validity and reliability of CogEvo were examined using factor analysis, MacDonald's omega reliability coefficient, logistic regression analysis, and receiver operating characteristic curve analysis.

Results

Exploratory factor analysis revealed the orientation/spatial cognitive function (orientation and spatial cognition) and attention/executive function (attention, memory, and execution) factors. Structural validity was supported by confirmatory factor analysis. All two-factor-based subtasks showed adequate internal consistency (MacDonald's omega ≥0.6). The total CogEvo score and two-factor scores were significantly correlated with neuropsychological test results. Based on the total CogEvo score, the cognitively normal and cognitive decline groups were identified by receiver operating characteristic curve analysis with a moderate predictive performance. The cognitive decline group was well identified using the orientation/spatial cognitive function factor.

Conclusions

CogEvo is a valid and reliable screening tool for cognitive function evaluation. It proved useful in the early identification of cognitive decline in our study sample.

Executive function abilities in cognitively healthy young and older adults-A cross-sectional study

A prominent feature of cognitive aging is the decline of executive function (EF) abilities. Numerous studies have reported that older adults perform poorer than younger adults in such tasks. In this cross-sectional study, the effect of age on four EFs, inhibition, shifting, updating, and dual-tasking, was examined in 26 young adults (mean 21.18  years) and 25 older adults (mean 71.56  years) with the utilization of a pair of tasks for each EF. The tasks employed for DT were the Psychological Refractory Period paradigm (PRP) and a modified test for everyday attention, for inhibition the Stroop and Hayling sentence completion test (HSCT), for shifting a task switching paradigm and the trail making test (TMT), and for updating the backward digit span (BDS) task and a n-back paradigm. As all participants performed all tasks, a further aim was to compare the size of the age-related cognitive decline among the four EFs. Age-related decline was observed in all four EFs in one or both of the tasks employed. The results revealed significantly poorer performance in the older adults in the response times (RTs) of the PRP effect, interference score of the Stroop, RT inhibition costs of the HSCT, RT and error-rate shifting costs of the task switching paradigm, and the error-rate updating costs of the n-back paradigm. A comparison between the rates of decline revealed numerical and statistically significant differences between the four EFs, with inhibition showing the greatest decline, followed by shifting, updating, and dual-tasking. Thus, we conclude that with age, these four EFs decline at different rates.

Assessing cognitive flexibility in humans and rhesus macaques with visual motion and neutral distractors

Introduction

Cognitive flexibility is the ability of an individual to make behavioral adjustments in response to internal and/or external changes. While it has been reported in a wide variety of species, established paradigms to assess cognitive flexibility vary between humans and non-human animals, making systematic comparisons difficult to interpret.

Methods

We developed a computer-based paradigm to assess cognitive flexibility in humans and non-human primates. Our paradigm (1) uses a classical reversal learning structure in combination with a set-shifting approach (4 stimuli and 3 rules) to assess flexibility at various levels; (2) it employs the use of motion as one of three possible contextual rules; (3) it comprises elements that allow a foraging-like and random interaction, i.e., instances where the animals operate the task without following a strategy, to potentially minimize frustration in favor of a more positive engagement.

Results and Discussion

We show that motion can be used as a feature dimension (in addition to commonly used shape and color) to assess cognitive flexibility. Due to the way motion is processed in the primate brain, we argue that this dimension is an ideal candidate in situations where a non-binary rule set is needed and where participants might not be able to fully grasp other visual information of the stimulus (e.g., quantity in Wisconsin Card Sorting Test). All participants in our experiment flexibly shifted to and from motion-based rules as well as color- and shape-based rules, but did so with different proficiencies. Overall, we believe that with such approach it is possible to better characterize the evolution of cognitive flexibility in primates, as well as to develop more efficient tools to diagnose and treat various executive function deficits.

Executive functions in primary progressive aphasia: A meta-analysis

Executive functions (EFs) refer to a set of cognitive processes, specifically shifting, inhibition, updating of working memory, and are involved in the cognitive control of behavior. Conflicting results have been reported regarding impairments of EFs in Primary Progressive Aphasia (PPA). We performed a multi-level meta-analysis to confirm whether deficits of EFs exist in this population, focusing on a common EFs composite, and the components shifting, inhibition and updating separately. We included 141 studies that report on 294 EFs tasks. The overall mean weighted effect size was large (d = -1,28), indicating poorer EFs in PPA as compared to age-matched cognitively healthy controls. Differences between effect sizes of the EFs components were not significant, indicating all components are affected similarly. Overall, moderator analysis revealed that PPA variant and disease duration were significant moderators of performance, while task modality and years of education were not. The non-fluent/agrammatic PPA and the logopenic PPA variants were similarly affected, but the semantic variant was affected to a lesser extent. We discuss implications for clinical and research settings, and future research.

Neuropsychological profile of executive functions in autism spectrum disorder and schizophrenia spectrum disorders: a comparative group study in adults

As assessed by numerous neuropsychological tasks, individuals with autism spectrum disorder (ASD) and schizophrenia spectrum disorders (SSDs) have similar impairments related to executive functions (EFs). The neuropsychological profile of these two conditions was examined using the three-component EFs' framework of Miyake and Friedman (Cogn Psychol 41(1):49-100, 2000). This approach assesses Inhibition (suppression of unwanted and irrelevant information/responses), Updating (use and control of contents of working memory), and Shifting (disengagement between activities or mental tasks) using nine different tasks. In line with previous research, we expected greater performance deficits in ASD in all three components compared to SSD, as well as faster responses for the SSD group. A self-paced task format allowed us to examine whether unlimited time given for a task would lead to better performance. The sample was constituted by the control group (N = 25), ASD group (N = 24), and SSD group (N = 12). Groups did not differ on Inhibition performance. In Updating, individuals with SSD performed poorer than the other groups. As for Shifting, both groups demonstrated poorer performance compared to controls, with the SSD group presenting the greatest difficulties. In terms of reaction time (RT), SSD participants' RT were the slowest on Inhibition and Shifting tasks. There was a positive correlation between performance and time spent on Inhibition and Shifting only for the SSD group, which demonstrates that their performance improves when there are no time constraints. Our work provides a better understanding of spared and impaired EFs, which could be useful for designing strategies aimed at improving specific EFs in each group.

The "Ifs" and "Hows" of the Role of Music on the Implementation of Emotional Regulation Strategies

Music is believed to aid the implementation of emotion regulation strategies like distraction or reappraisal, but empirical studies have shown null results. However, the moderating role of one’s relation with music (musical sophistication) and/or executive functioning skills has not been considered yet. In addition, little is known about how music acts. In the present study, we induced anger in a group of participants characterized by musical sophistication and executive functioning. We asked them to regulate their emotional state and measured regulation efficacy. Participants were split into four groups, defined by regulation strategy (distraction vs. reappraisal) and music (with vs. without). Results indicated music effects in higher, but not in lower musical sophistication participants. In the former, music benefitted from reappraisal but was an impaired distraction. Two different executive functions—working memory and affective flexibility—had opposite effects: higher, but not lower working memory participants benefited from music; lower, but not higher, effective flexibility participants took advantage of music. Reports of subjective experience suggested that music favors more empathic reappraisals, and that these may be more long-lasting. Our findings support the idea that music effects depend on listeners’ characteristics, and they raise new hypotheses concerning the specificity of emotional regulation aided by music.

Episodic Memory and Executive Function Are Differentially Affected by Retests but Similarly Affected by Age in a Longitudinal Study of Normally-Aging Older Adults

Episodic memory and executive function are two cognitive domains that have been studied extensively in older adults and have been shown to decline in normally-aging older individuals. However, one of the problems with characterizing cognitive changes in longitudinal studies has been separating effects attributable to normal aging from effects created by repeated testing or practice. In the present study, 166 people aged 65 and older were enrolled over several years and tested at least 3 times at variable intervals (M = 3.2 yrs). The cognitive measures were composite scores. Each composite was made up of five neuropsychological tests, previously identified through factor analysis. For one pair of composite scores, variance attributable to age was removed from each subtest through regression analyses before z-scores were computed, creating two age-corrected composites. A second pair of composites were not age-corrected. Using linear mixed-effects models, we first explored retest effects for each cognitive domain, independent of age, using the age-corrected composites. We then modeled aging effects using the age-uncorrected composites after subtracting out retest effects. Results indicated significant retest effects for memory but not for executive function, such that memory performance improved across the three testing sessions. When these practice effects were removed from the age-uncorrected data, effects of aging were evident for both executive and memory function with significant declines over time. We also explored several individual difference variables including sex, IQ, and age at the initial testing session and across time. Although sex and IQ affected performance on both cognitive factors at the initial test, neither was related to practice effects, although young-older adults tended to benefit from practice to a greater extent than old-older adults. In addition, people with higher IQs showed slower age-related declines in memory, but no advantages in executive function. These findings suggest that (a) aging affects both memory and executive function similarly, (b) higher IQ, possibly reflecting cognitive reserve, may slow age-related declines in memory, and (c) practice through repeated testing enhances performance in memory particularly in younger-older adults, and may therefore mask aging effects if not taken into account.

A machine learning approach for the factorization of psychometric data with application to the Delis Kaplan Executive Function System

While a replicability crisis has shaken psychological sciences, the replicability of multivariate approaches for psychometric data factorization has received little attention. In particular, Exploratory Factor Analysis (EFA) is frequently promoted as the gold standard in psychological sciences. However, the application of EFA to executive functioning, a core concept in psychology and cognitive neuroscience, has led to divergent conceptual models. This heterogeneity severely limits the generalizability and replicability of findings. To tackle this issue, in this study, we propose to capitalize on a machine learning approach, OPNMF (Orthonormal Projective Non-Negative Factorization), and leverage internal cross-validation to promote generalizability to an independent dataset. We examined its application on the scores of 334 adults at the Delis-Kaplan Executive Function System (D-KEFS), while comparing to standard EFA and Principal Component Analysis (PCA). We further evaluated the replicability of the derived factorization across specific gender and age subsamples. Overall, OPNMF and PCA both converge towards a two-factor model as the best data-fit model. The derived factorization suggests a division between low-level and high-level executive functioning measures, a model further supported in subsamples. In contrast, EFA, highlighted a five-factor model which reflects the segregation of the D-KEFS battery into its main tasks while still clustering higher-level tasks together. However, this model was poorly supported in the subsamples. Thus, the parsimonious two-factors model revealed by OPNMF encompasses the more complex factorization yielded by EFA while enjoying higher generalizability. Hence, OPNMF provides a conceptually meaningful, technically robust, and generalizable factorization for psychometric tools.

Education Moderates the Negative Effect of Apolipoprotein E ɛ4 on Response Inhibition in Older Adults

BACKGROUND

Studies have reported that apolipoprotein E epsilon 4 (APOE ɛ4) has adverse effects on executive functions (EFs) in late adulthood. However, the results have been inconsistent. Insufficient measurements of executive functioning, uncontrolled clinical and demographic confounders, and moderation effects from other environmental factors are suspected to account for the inconsistency.

OBJECTIVE

This study used aggregate measures to examine the effects of APOE ɛ4 on four components of EFs, namely switching, working memory, inhibition, and reasoning. We further investigated whether high educational attainment, a proxy measure for cognitive reserve, moderates the adverse effects of ɛ4 on EFs.

METHODS

Cognitively unimpaired older participants were divided into groups based on APOE genotype and into subgroups based on educational attainment level. The demographic and clinical variables were matched between the groups. Four core components of the EFs were measured using a relatively comprehensive battery.

RESULTS

The results revealed that although no main effect of the APOE genotype was observed across the four EF components, the potentially adverse effects of ɛ4 on inhibition were alleviated by high educational attainment. A main effect of education on the reasoning component was also observed. The moderation analysis revealed that for older adults with 12 years of education or fewer, the relationship between the APOE ɛ4 genotype and inhibition performance became increasingly negative.

CONCLUSION

This study highlights the distinctive role of response inhibition in the gene-environment interaction and underlines the importance of considering factors of both nature and nurture to understand the complex process of cognitive aging.