Wisconsin Card Sort Test performance in a healthy elderly population

Split-half reliability estimates of an online card sorting task in a community sample of young and elderly adults

Executive function is vital for normal social, cognitive, and motor functions. Executive function decline due to aging increases the risk of disability and falls in older adults, which has become an urgent public health issue. Fast and convenient neuropsychological tools are thus needed to identify high-risk groups as early as possible to conduct a timely intervention. Card sorting tasks, such as Wisconsin Card Sorting Task (WCST) and its variants, are popular tools for measuring executive function. This study investigated the reliability of an open-source, self-administered, online, short-version card sorting task with a sample of young (n = 107, 65 females, age: M = 30.1 years, SD = 5.5 years) and elderly Chinese (n = 113, 53 females, age: M = 64.0 years, SD = 6.7 years). We developed an automated scoring and visualization procedure following the recent recommendations on scoring perseverative responses to make the results comparable to the standardized WCST. Reliability estimates of commonly used measures were calculated using the split-half method. All task indices' reliabilities were reasonably good in both old and young groups except for "failure-to-maintain-set." Elderly Chinese adults showed compromised task performance on all measures compared with the young Chinese adults at the group level. The R script of automated scoring and estimation of reliability is publicly available.

Executive Functions in Aging: An Experimental and Computational Study of the Wisconsin Card Sorting and Brixton Spatial Anticipation Tests

In order to explore the effect of normal aging on executive function, we tested 25 younger adults and 25 neurologically healthy older adults on the Wisconsin Card Sorting Test (WCST) and the Brixton Spatial Anticipation Test (BRXT), two classic tests of executive function. We found that older participants were more likely than younger participants to err on both tasks, but the additional errors of older participants tended to be related to task set maintenance and rule inference rather than perseveration. We further found that the tendency to perseverate (across all participants) on the WCST was related to the tendency to produce stimulus or response perseverations on the BRXT, rather than any tendency to perseverate on BRXT rule application. Finally, on both tasks, older participants were also slower, particularly on trials following an error, than younger participants. To explore the neurocomputational basis for the observed behaviours we then extended an existing model of schema-modulated action selection on the WCST to the BRXT. We argue on the basis of the model that the performance of older participants on both tasks reflects a slower update of schema thresholds within the basal ganglia, coupled with a decrease in sensitivity to feedback.

Interaction of cholinergic disruption and age on cognitive flexibility in rats

Healthy aging is associated with a functional reduction of the basal forebrain (BF) system that supplies the neurochemical acetylcholine (ACh) to the cortex, and concomitant challenges to cognition. It remains unclear how aging and ACh loss interact to shape cognition in the aging brain. We used a proactive interference (PI) odor discrimination task, shown to depend on the BF in young adults, wherein rats acquired new associations that conflicted with past learning or associations that did not conflict. This manipulation allowed independent assessment of encoding alone vs. encoding in the face of interference. Adult (9.8 ± 1.3 months) or aged male Long-Evans rats (20.7 ± 0.5 months) completed the PI task with systemic administration of a muscarinic cholinergic antagonist, scopolamine, or a pharmacological control. Aged rats were less able to resolve PI than adult rats. Moreover, while scopolamine reduced efficient PI resolution in adult rats, this cholinergic antagonism had no additional effect on aged rat performance, counter to our expectation that scopolamine would further increase perseveration in the aged group. Scopolamine did not impair encoding of non-interfering associations regardless of age. These data suggest that natural aging changes the effect of cholinergic pharmacology on encoding efficiency when past learning interferes.

Cognitive and Motor Perseveration Are Associated in Older Adults

Aging causes perseveration (difficulty to switch between actions) in motor and cognitive tasks, suggesting that the same neural processes could govern these abilities in older adults. To test this, we evaluated the relation between independently measured motor and cognitive perseveration in young (21.4 ± 3.7 y/o) and older participants (76.5 ± 2.9 y/o). Motor perseveration was measured with a locomotor task in which participants had to transition between distinct walking patterns. Cognitive perseveration was measured with a card matching task in which participants had to switch between distinct matching rules. We found that perseveration in the cognitive and motor domains were positively related in older, but not younger individuals, such that participants exhibiting greater perseveration in the motor task also perseverated more in the cognitive task. Additionally, exposure reduces motor perseveration: older adults who had practiced the motor task could transition between walking patterns as proficiently as naïve, young individuals. Our results suggest an overlap in neural processes governing cognitive and motor perseveration with aging and that exposure can counteract the age-related motor perseveration.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mental Flexibility Influences the Association Between Poor Balance and Falls in Older People - A Secondary Analysis

Impairments of balance predispose older people to falls. Some cognitive functions, especially executive functioning have been shown to affect balance and discriminate fallers from non-fallers. Mental flexibility is a component of the executive function and comprises multiple cognitive processes that work together to adjust the course of thoughts or actions according to the changing demands of a situation without the use of explicit instructions. However, the role of mental flexibility in balance in older people remains unclear. The study aim was to examine the relationship between mental flexibility and falls in a cohort of 212 older people (80.6 ± 4.9 years; 62% female). We hypothesized that: (i) participants with impaired balance would have worse mental flexibility compared to those with good balance; and (ii) poor mental flexibility would predict falls in the sub-group with impaired balance. Balance performance was assessed by measuring postural sway while standing on a medium density foam mat with eyes open for 30 s. Mental flexibility was assessed using a computerized short-form of the Wisconsin Card Sorting Test (WCST; 64 cards) with its sub-components comprising general performance, perseveration, failure-to-maintain set and conceptual ability. Falls were measured prospectively for 12-months using monthly calendars. MANCOVA revealed that WCST performance was associated with balance [Wilks' Lambda = 0.883, F = 2.168; p = 0.013, partial eta squared ( η p 2 ) = 0.061] due primarily to reduced concept formation ability [F _(2,207) = 5.787, p = 0.004, η p 2 = 0.053]. Negative binomial regression analysis adjusting for age, education, contrast sensitivity, proprioception, inhibition, and inhibitory choice stepping reaction time (iCSRT) revealed that lower concept formation ability was predictive for falls [Incidence Rate Ratio 1.048 (95% confidence interval 1.016-1.081)]. Further, lower concept formation ability partly explained the association between balance and falls: i.e., fallers in the upper balance tertile had reduced concept formation performance whereas non-fallers had similar concept formation performance across the three balance tertiles. These findings suggest that poor mental flexibility affects the ability to maintain steady balance contributing to increased risk of falls in older people.

Association Between Executive Dysfunction and Instrumental Activities of Daily Living: Racial and Ethnic Differences Among Community-Dwelling Older Adults in the Southeastern US

OBJECTIVE

Examining cultural differences in assessment of cognitive/functional disability among older Americans is needed. This analysis examined associations between day-to-day function, measured by activities of daily living (ADL), and cognition, measured by CLOX scores, among older African American (AA) and non-Hispanic White (nHW) community-dwelling women and men.

METHODS

Design- Cross-sectional.

SETTING

Homes of community-dwelling older adults. Participants- 893 Medicare beneficiaries >65 living in west-central Alabama, without diagnoses of dementia, who were participants in the University of Alabama at Birmingham (UAB) Study of Aging, and who had complete data. Measurements- Physical function was assessed by self-reported ADL difficulty; cognitive function by CLOX, a clock drawing-task. Multivariable, linear regression models were used to examine associations within race/sex specific groups.

RESULTS

After controlling for socio-demographic factors and comorbidities, CLOX1 scores were inversely and significantly correlated with ADL for AA men (β = -0.205, P = 0.003). CLOX2 scores were similarly associated with ADL and IADL for the total group (β = -0.118, P = 0.001, and β = -0.180, P < 0.001, respectively); for ADL, significant associations were seen for AA men and nHW women (β = -0.203, P = 0.004, and β = -0.139, P = 0.02, respectively) and, for IADL, in AA women and men (β = -0.156, P = 0.03, and β = -0.24, P < 0.001, respectively).

CONCLUSION

While African American women reported the highest difficulty with ADLs and IADLs among all race/sex groups, CLOX1 scores were correlated with ADL for AA men only. CLOX1 may have limitations to identify functional disability for older AA women. [Word Count = 234].

Do Normative Data From the Full WCST Extend to the Abbreviated WCST?

The standard Wisconsin Card Sorting Test (WCST) was administered to a mixed clinical sample of 332 individuals. The full version was compared to the 64-card version (WCST-64) by extracting the results of the first 64 cards. Percent scores for the WCST were converted to standard scores using the normative data corrected for age and education level. Percent scores for WCST-64 were converted to standard scores using the same WCST normative data. WCST-64 scores were not comparable to those obtained from the full WCST. A breakdown of the data based on performance level found WCST-64 to be useful only with respondents obtaining five or more categories by the end of the first deck. The authors recommend caution in applying WCST manual data to the WCST-64 in the clinical setting.

Executive Dysfunction Following Critical Illness: Exploring Risk Factors and Management Options in Geriatric Populations

Cognitive impairment is a common occurrence that has been shown to occur in over 50 % of patients following critical illness. This impairment occurs across a range of domains including attention, memory, processing speed, and executive dysfunction. In this article, we will discuss the pathophysiology behind cognitive impairment including hypoxemia and cytokines. Secondly, we will describe the risk factors for cognitive impairment including age, length of stay, and delirium. Lastly, we will review emerging data related to the use of cognitive rehabilitation, formation of postintensive care clinics in qualifying patients, and potential neuropharmacologic therapy. While our chapter focuses on cognitive impairment generally, it places a particular emphasis on executive dysfunction, not because impairment occurs solely in this domain but because impairments of an executive nature may be uniquely debilitating.

"Executive functions" cannot be distinguished from general intelligence: two variations on a single theme within a symphony of latent variance

The empirical foundation of executive control function (ECF) remains controversial. We have employed structural equation models (SEM) to explicitly distinguish domain-specific variance in executive function (EF) performance from memory (MEM) and shared cognitive performance variance, i.e., Spearman's “g.” EF does not survive adjustment for both MEM and g in a well fitting model of data obtained from non-demented older persons (N = 193). Instead, the variance in putative EF measures is attributable only to g, and related to functional status only through a fraction of that construct (i.e., “d”). d is a homolog of the latent variable δ, which we have previously associated specifically with the Default Mode Network (DMN). These findings undermine the validity of EF and its putative association with the frontal lobe. ECF may have no existence independent of general intelligence, and no functionally salient association with the frontal lobe outside of that structure's contribution to the DMN.

Executive cognitive dysfunction and ADHD in cocaine dependence: searching for a common cognitive endophenotype for addictive disorders

BACKGROUND

Cocaine-dependent individuals (CDI) present executive cognitive function (ECF) deficits, but the impact of psychiatric comorbidities such as Attention-Deficit Hyperactivity Disorder (ADHD) on neuropsychological functioning is still poorly understood. The aim of this study was to investigate if CDI with ADHD (CDI + ADHD) would have a distinct pattern of executive functioning when compared with CDI without ADHD (CDI).

METHODS

We evaluated 101 adults, including 69 cocaine-dependent subjects (divided in CDI and CDI + ADHD) and 32 controls. ECF domains were assessed with Digits Forward (DF), Digits Backward (DB), Stroop Color Word Test (SCWT), the Wisconsin Card Sorting Test (WCST), and the Frontal Assessment Battery (FAB). DSM-IV criteria for ADHD were used for diagnosis and previous ADHD symptoms (in the childhood) were retrospectively assessed by the Wender-Utah Rating Scale (WURS).

RESULTS

There were no significant differences between CDI + ADHD, CDI, and controls in estimated intellectual quotient (IQ), socioeconomic background, education (in years), and pre-morbid IQ (p > 0.05). SCWT and WCST scores did not differ across groups (p > 0.05). Nevertheless, CDI and CDI + ADHD performed more poorly than controls in total score of the FAB (p < 0.05). Also, CDI + ADHD did worse than CDI on DF (F = 4.756, p = 0.011), DB (F = 8.037, p = 0.001), Conceptualization/FAB (F = 4.635, p = 0.012), and Mental flexibility/FAB (F = 3.678, p = 0.029). We did not find correlations between cocaine-use variables and neuropsychological functioning, but previous ADHD symptoms assessed by WURS were negatively associated with DF (p = 0.016) and with the total score of the FAB (p = 0.017).

CONCLUSION

CDI + ADHD presented more pronounced executive alterations than CDI and CDI exhibited poorer cognitive functioning than controls. Pre-existing ADHD symptoms may have a significant negative impact on executive dysfunction in CDI. It remains to be investigated by future studies if symptoms such as impulsivity or a pre-existing ECF dysfunction could represent underlying cognitive endophenotypes that would substantially increase the risk for acquiring addictive disorders.

A review of intentional and cognitive control in autism

Different clinical studies have provided empirical evidence for impairments in cognitive control in individuals with autism spectrum disorders (ASD). The challenge arises, however, when trying to specify the neurocognitive mechanisms behind the reported observations of deviant patterns of goal-directed behavior in ASD. Studies trying to test specific assumptions by applying designs that are based on a more controlled experimental conditions often fail in providing strong evidence for an impairment in specific cognitive functions. In this review, we summarize and critically reflect on behavioral findings and their theoretical explanations regarding cognitive control processing in autism, also from a developmental perspective. The specific focus of this review is the recent evidence of deficits in intentional control – a specific subset of cognitive control processes that biases the choice of our behavioral goals – coming from different research fields. We relate this evidence to the cognitive rigidity observed in ASD and argue that individuals with ASD experience problems at the intentional level rather than at the level of implementation of intentions. Both these processes are related to cognitive control mechanisms but in different ways. Finally, we discuss new directions in studying cognitive control in ASD and how these relate to adaptive cognition.

Neuronal and morphological bases of cognitive decline in aged rhesus monkeys

Rhesus monkeys provide a valuable model for studying the basis of cognitive aging because they are vulnerable to age-related decline in executive function and memory in a manner similar to humans. Some of the behavioral tasks sensitive to the effects of aging are the delayed response working memory test, recognition memory tests including the delayed nonmatching-to-sample and the delayed recognition span task, and tests of executive function including reversal learning and conceptual set-shifting task. Much effort has been directed toward discovering the neurobiological parameters that are coupled to individual differences in age-related cognitive decline. Area 46 of the dorsolateral prefrontal cortex (dlPFC) has been extensively studied for its critical role in executive function while the hippocampus and related cortical regions have been a major target of research for memory function. Some of the key age-related changes in area 46 include decreases in volume, microcolumn strength, synapse density, and α1- and α2-adrenergic receptor binding densities. All of these measures significantly correlate with cognitive scores. Interestingly, the critical synaptic subtypes associated with cognitive function appear to be different between the dlPFC and the hippocampus. For example, the dendritic spine subtype most critical to task acquisition and vulnerable to aging in area 46 is the thin spine, whereas in the dentate gyrus, the density of large mushroom spines with perforated synapses correlates with memory performance. This review summarizes age-related changes in anatomical, neuronal, and synaptic parameters within brain areas implicated in cognition and whether these changes are associated with cognitive decline.

Route learning impairment in temporal lobe epilepsy

Memory impairment on neuropsychological tests is relatively common in temporal lobe epilepsy (TLE) patients. However, memory has been rarely evaluated in more naturalistic settings. This study assessed TLE (n=19) and control (n=32) groups on a real-world route learning (RL) test. Compared to the controls, the TLE group committed significantly more total errors across the three RL test trials. Route learning errors correlated significantly with standardized auditory and visual memory and visual-perceptual test scores in the TLE group. In the TLE subset for whom hippocampal data were available (n=14), RL errors also correlated significantly with left hippocampal volume. This is one of the first studies to demonstrate real-world memory impairment in TLE patients and its association with both mesial temporal lobe integrity and standardized memory test performance. The results support the ecological validity of clinical neuropsychological assessment.

Executive function on the Psychology Experiment Building Language tests

The measurement of executive function has a long history in clinical and experimental neuropsychology. The goal of the present report was to determine the profile of behavior across the lifespan on four computerized measures of executive function contained in the recently developed Psychology Experiment Building Language (PEBL) test battery http://pebl.sourceforge.net/ and evaluate whether this pattern is comparable to data previously obtained with the non-PEBL versions of these tests. Participants (N = 1,223; ages, 5-89 years) completed the PEBL Trail Making Test (pTMT), the Wisconsin Card Sort Test (pWCST; Berg, Journal of General Psychology, 39, 15-22, 1948; Grant & Berg, Journal of Experimental Psychology, 38, 404-411, 1948), the Tower of London (pToL), or a time estimation task (Time-Wall). Age-related effects were found over all four tests, especially as age increased from young childhood through adulthood. For several tests and measures (including pToL and pTMT), age-related slowing was found as age increased in adulthood. Together, these findings indicate that the PEBL tests provide valid and versatile new research tools for measuring executive functions.

Learning and generalization in healthy aging: implication for frontostriatal and hippocampal function

Damage to the hippocampal and frontostriatal systems can occur across the adult life span. As these 2 systems are involved in learning processes, mild impairments of learning and generalization might be observed even in healthy aging. In this study, we examined both learning and generalization performance in 3 groups of older adults: young-older (ages 45 to 60 y), middle-older (ages 61 to 75 y), and oldest-older (ages 76 to 90 y). We used a simple computerized concurrent discrimination task in which the learning phase has shown sensitivity to frontostriatal dysfunction, and the generalization phase to hippocampal damage. We found that age significantly affected initial learning performance, but generalization was spared in all but the oldest group, with some individuals still generalizing very well. This finding suggests that (a) learning abilities are affected in healthy aging (consistent with earlier reports of frontostriatal dysfunction in healthy aging) and (b) generalization deficit does not necessarily occur in early older age. We hypothesize that generalization deficits in some in the oldest group may be related to hippocampal pathology. Our data shed light on possible neural system dysfunction in healthy aging and Alzheimer disease.

Differences in Conceptual Flexibility with Age as Measured by a Modified Version of the Visual Verbal Test

Age-related changes in the capacity for cognitive flexibility should be considered in social planning for the expanding elderly population and in the functional assessment of the individual geriatric patient. Current means for assessing conceptual flexibility are not particularly appropriate for use with the elderly. In the current study, a briefer and more tolerable measure of conceptual flexibility was derived from the Visual Verbal Test (VVT). This index correlated significantly with the number of perseverative errors but not the number of nonperseverative errors on the Wisconsin Card Sorting Test (WCST), attesting to its validity as a specific measure of the ability to shift mental set. A significant relationship between age and both this VVT measure of conceptual shift and the number of perseverative errors on the WCST was observed in a sample of 60 healthy elderly volunteers between the ages of 55 and 84, suggesting that cognitive flexibility is indeed negatively associated with age.

Decision-making deficits linked to real-life social dysfunction in crack cocaine-dependent individuals

Crack cocaine-dependent individuals (CCDI) present abnormalities in both social adjustment and decision making, but few studies have examined this association. This study investigated cognitive and social performance of 30 subjects (CCDI × controls); CCDI were abstinent for 2 weeks. We used the Social Adjustment Scale (SAS), Wisconsin Card Sorting Test (WCST), and Iowa Gambling Task (IGT). Disadvantageous choices on the IGT were associated with higher levels of social dysfunction in CCDI, suggesting the ecological validity of the IGT. Social dysfunction and decision making may be linked to the same underlying prefrontal dysfunction, but the nature of this association should be further investigated. 

The frontal assessment battery (FAB) reveals neurocognitive dysfunction in substance-dependent individuals in distinct executive domains: Abstract reasoning, motor programming, and cognitive flexibility

Substance-dependence is highly associated with executive cognitive function (ECF) impairments. However, considering that it is difficult to assess ECF clinically, the aim of the present study was to examine the feasibility of a brief neuropsychological tool (the Frontal Assessment Battery - FAB) to detect specific ECF impairments in a sample of substance-dependent individuals (SDI). Sixty-two subjects participated in this study. Thirty DSM-IV-diagnosed SDI, after 2weeks of abstinence, and 32 healthy individuals (control group) were evaluated with FAB and other ECF-related tasks: digits forward (DF), digits backward (DB), Stroop Color Word Test (SCWT), and Wisconsin Card Sorting Test (WCST). SDI did not differ from the control group on sociodemographic variables or IQ. However, SDI performed below the controls in DF, DB, and FAB. The SDI were cognitively impaired in 3 of the 6 cognitive domains assessed by the FAB: abstract reasoning, motor programming, and cognitive flexibility. The FAB correlated with DF, SCWT, and WCST. In addition, some neuropsychological measures were correlated with the amount of alcohol, cannabis, and cocaine use. In conclusion, SDI performed more poorly than the comparison group on the FAB and the FAB's results were associated with other ECF-related tasks. The results suggested a negative impact of alcohol, cannabis, and cocaine use on the ECF. The FAB may be useful in assisting professionals as an instrument to screen for ECF-related deficits in SDI.

Processing speed, inhibitory control, and working memory: three important factors to account for age-related cognitive decline

Processing speed, inhibitory control and working memory have been identified as the main possible culprits of age-related cognitive decline. This article describes a study of their interrelationships and dependence on age, including exploration of whether any of them mediates between age and the others. We carried out a LISREL analysis of the performance of 79 participants of low educational level aged 40-91 years in six cognitive tasks. In the best mediational model the effects of age on inhibitory control and working memory are largely mediated by its effect on processing speed. However, in the best-fitting model age has only direct effects on processing speed, working memory, and inhibitory control.

Healthy ageing, perceived motor-efficacy, and performance on cognitively demanding action tasks

Current measures assessing older adults' functional ability detect existing limitations on essential tasks rather than changes in other aspects of functioning that could indicate future limitations. The perceived motor-efficacy scale was developed to measure capability beliefs of healthy older adults across a range of daily action tasks. Subscales were developed through interviews with older volunteers and academics, then administered to participants aged 60-96 (N=300). Factor analysis of subscale scores produced 10 subscales. These demonstrated strong internal reliability, which was replicated with a second sample aged 60-92 (N=167). The influence of perceived motor-efficacy on performance of cognitively demanding action tasks was investigated with a third sample aged 60-88 (N=134). On a task assessing the inhibition of an inappropriate action, older adults in their 80s with high confidence produced minor errors, whereas those with lower confidence produced extreme errors. On another task assessing the ability to inhibit a previously learnt action, those with high levels of perceived motor-efficacy performed better amongst those least able to inhibit, but more poorly among those most able. Perceived motor-efficacy may therefore be useful in identifying older adults at risk of functional limitations and enabling interventions before the onset of illness.

Aging and Inhibition of a Prepotent Motor Response during an Ongoing Action

Inhibitory functions are key mechanisms underlying age related decline (Park & Gutchess, 2000, in: Cognitive aging: A primer. Hove: Psychology Press), yet few studies have investigated their impact on everyday tasks involving action as well as cognition. Using an everyday-based go/no-go task we devised a motor analogy of traditional neuropsychological tests to investigate in 134 older (aged 60-88) and 133 younger adults (aged 20-59) the ability to inhibit a prepotent motor response during an ongoing action. Older adults produced more inhibition failures as expected, but more strikingly inhibitory errors were not all or none; even when the inappropriate response was successfully inhibited, difficulties controlling ongoing movements emerged from as young as people in their 40s. The ability to inhibit therefore does not ensure control of ongoing tasks, and traditional cognitive tests may be unable to detect such difficulties. Furthermore, performance did not covary with education or action speed. Implications for neuropsychological theory and assessing/enhancing functional ability are discussed.

The elusive nature of executive functions: a review of our current understanding

Executive functions include abilities of goal formation, planning, carrying out goal-directed plans, and effective performance. This article aims at reviewing some of the current knowledge surrounding executive functioning and presenting the contrasting views regarding this concept. The neural substrates of the executive system are examined as well as the evolution of executive functioning, from development to decline. There is clear evidence of the vulnerability of executive functions to the effects of age over lifespan. The first executive function to emerge in children is the ability to inhibit overlearned behavior and the last to appear is verbal fluency. Inhibition of irrelevant information seems to decline earlier than set shifting and verbal fluency during senescence. The sequential progression and decline of these functions has been paralleled with the anatomical changes of the frontal lobe and its connections with other brain areas. Generalization of the results presented here are limited due to methodological differences across studies. Analysis of these differences is presented and suggestions for future research are offered.

Cognitive, neurophysiological, and functional correlates of proverb interpretation abnormalities in schizophrenia

A hallmark of schizophrenia is impaired proverb interpretation, which could be due to: (1) aberrant activation of disorganized semantic associations, or (2) working memory (WM) deficits. We assessed 18 schizophrenia patients and 18 normal control participants on proverb interpretation, and evaluated these two hypotheses by examining within patients the correlations of proverb interpretation with disorganized symptoms and auditory WM, respectively. Secondarily, we also explored the relationships between proverb interpretation and a spectrum of cognitive functions including auditory sensory-memory encoding (as indexed by the mismatch negativity (MMN) event-related brain potential (ERP)); executive function; and social/occupational function. As expected, schizophrenia patients produced less accurate and less abstract descriptions of proverbs than did controls. These proverb interpretation difficulties in patients were not significantly correlated with disorganization or other symptom factors, but were significantly correlated (p < .05) with WM impairment, as well as with impairments in sensory-memory encoding, executive function, and social/occupational function. These results offer no support for disorganized associations in abnormal proverb interpretation in schizophrenia, but implicate WM deficits, perhaps as a part of a syndrome related to generalized frontal cortical dysfunction.

Gender differences in executive functions following traumatic brain injury

The present study used the National Institute on Disability Rehabilitation and Research (NIDRR) funded Traumatic Brain Injury Model Systems (TBIMS) database to examine the effect of gender on presentation of executive dysfunction following traumatic brain injury (TBI) and variables that might impact the course and degree of recovery. The Wisconsin Card Sort Test (WCST) was chosen as a measure of executive function which has good credentials without reports of gender effects. Female subjects performed significantly better on the WCST than male subjects as shown by analyses of variance on scores of 1,331 patients for Categories Achieved (means for females = 4.09, males = 3.67, p = .003) and Perseverative Responses (means for females = 32.17, males = 36.42, p = .003). Outperformance by females was also noted in additional ANOVAs examining the interaction of education and gender, and ethnicity and gender in relation to Categories Achieved (p < .01), and for ethnicity and gender in relation to Perseverative Responses (p < .01). A multiple logistic regression revealed that gender, minority status, education level, history of illicit drug use, cause of injury, and length of coma each contributed uniquely to predicting Categories Achieved on the WCST. Simple logistic regression analyses showed that, of these variables, gender and cause of injury (violent vs. non-violent) were the strongest predictors. In contrast, when examining Perseverative Responses, regression analyses found gender, minority status and length of coma predicted impairment. Simple logistic regression analyses showed that, of these three variables, gender and minority status were most robust in predicting impaired Perseverative Responses scores. Implications of these findings are discussed and recommendations for further research are offered.

Correlational study of the Chinese version of the executive interview (C-EXIT25) to other cognitive measures in a psychogeriatric population in Hong Kong Chinese

OBJECTIVES

This study is designed to pilot test the feasibility and correlational properties of the adapted Chinese version of Executive Interview (C-EXIT25) to other cognitive measures in a psychogeriatric population in Hong Kong Chinese.

METHOD

Eighty-five community dwelling elders from different levels of residential care facilities were assessed with C-EXIT25, Cantonese version of Mini-Mental State Examination (C-MMSE), Chinese version of Mattis Dementia Rating Scale (CDRS) and Nelson's Modified Card Sorting Test (MCST).

RESULTS

The C-EXIT25 has high internal consistency (Cronbach's alpha = 0.7995) and inter-rater reliability (r = 0.91). The C-EXIT25 has superior correlational property to performance indices of MCST than the C-MMSE and CDRS, after adjusting for age, gender and educational level. It also discriminates among subjects at different stages on Clinical Dementia Rating.

CONCLUSIONS

The C-EXIT25 is a potentially feasible and valid bedside tool for assessment of executive cognitive functions in the psychogeriatric population in Hong Kong Chinese.

Narrative speech in aging: quantity, information content, and cohesion

This study examined age-related changes in narrative speech of 79 adults aged 40-91 who told stories from their pictorial representations. Quantity, information content and cohesion of narratives were analysed using a detailed transcription and codification system. We carried out a LISREL analysis to study relationships between narrative performance and age, level of education and verbal capacity. Our results showed that aging increases quantity, reduces density of informational content and cohesive reference of narratives and increases the units of irrelevant content. Verbal capacity measured by a vocabulary test improves content and cohesion. The implications of the findings for the cognitive deficit and pragmatic change explanations of narrative speech are discussed.

Aging and inhibitory errors on a motor shift of set task

Inhibitory functions are key mechanisms underlying age-related cognitive decline (Park and Gutchess in Cognitive aging: a primer, Psychology Press, Hove 2000), yet how these influence the control of action has not been fully investigated. Using 134 older (age 60-88) and 133 younger adults (age 20-59), we investigated in a motor analogy of the WCST the inhibition of a primed movement plan in favour of a novel one. Although 10% of older adults performed similarly to young adults, the majority failed to inhibit by the sixties, 10-20 years earlier than documented for the WCST (Lezak in Neurological Assessment, Oxford University Press, New York 1995; Haaland et al. in J Gerontol 33:345-346 1987). Around 40% failed to learn on the second attempt, and of these, the majority in their sixties to eighties failed to learn eventually. Implications are discussed for neuropsychological theory and everyday interventions.

Normal rates of cognitive change in successful aging: the freedom house study

We determined the rates of cognitive change associated with twenty individual measures. Participants included 547 noninstitutionalized septuagenarians and octogenarian residents of a comprehensive care retirement community who were studied over three years. Latent growth curves (LGC) of multiple cognitive measures were compared to a LGC model of the rates of change in Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL). All curves were standardized relative to each variable's baseline distribution. Baseline scores were within their expected normal age-specific ranges. Most measures showed significant rates of change over time. There was also significant variability about those rates, suggesting clinical heterogeneity. Many deteriorated over time, as did ADLs and IADLs. However, performance on some measures improved, consistent with learning effects. The rates of change in two measures, the Executive Interview and the Trail Making Test, were closely related to decline in IADLs. These results suggest that age-related cognitive decline is a dynamic longitudinal process affecting multiple cognitive domains. Heterogeneity in the rates of cognitive change may reflect the summed effects of age and comorbid conditions affecting cognition. Some measures may be ill-suited for measuring age-related changes in cognition, either because they are insensitive to change, or hindered by learning effects. Nonverbal measures appear to be particularly well suited for the prediction of age-related functional decline. These observations are relevant to the definition and diagnosis of "dementing" conditions.

Executive system dysfunction occurs as early as middle-age in the rhesus monkey

As our understanding of age-related cognitive decline advances, studies are now focusing on identification of those areas of cognitive function that undergo the first changes with age. In the present study, in order to determine whether executive function is sensitive to the aging process, we assessed the performance of 16 monkeys of middle-age (12-19 years of age) on the conceptual set-shifting task, an analogue of the Wisconsin Card Sorting Test (WCST). We compared their performance to that of seven young adult (5-9 years of age) and 18 aged monkeys (20-30). The findings showed that middle-aged monkeys, like those of advanced age, were significantly impaired on the conceptual set-shifting task (CSST). These findings parallel those of recent studies in humans demonstrating an increase in perseverative errors on the WCST by middle-aged as well as aged individuals and, in turn, support the notion that disruption of executive function is one of the earliest changes in cognition to occur in normal aging.

Executive control mediates memory's association with change in instrumental activities of daily living: the Freedom House Study

OBJECTIVES

To assess the relative independent contribution of changes in executive control function (ECF) and memory to changes in functional status.

DESIGN

Three-year longitudinal cohort study.

SETTING

A comprehensive care retirement community.

PARTICIPANTS

Five hundred forty-seven noninstitutionalized people aged 70 and older.

MEASUREMENTS

The California Verbal Learning Test (CVLT) and Executive Interview (EXIT25). Functional status was assessed using instrumental activities of daily living (IADLs). Latent growth curves of CVLT, EXIT25, and IADLs were modeled. The rate of change in IADLs (adjusted for baseline IADLs and cognition) was regressed on the rate of change in each cognitive measure. Models were also adjusted for baseline age, level of care, and comorbid illnesses.

RESULTS

There was significant variability around the baseline means and slopes for all variables. The rate of change in EXIT25 was independently correlated with the rate of change in IADLs (correlation coefficient (r)=-0.52, P<.001). This remained significant after adjusting for baseline EXIT25 scores, IADLs, age, comorbid disease, and level of care. The EXIT25's effect on the rate of change in IADLs was stronger than those of age, baseline IADLs, comorbid disease, or level of care. The rate of change in CVLT scores was not significantly associated with the rate of change in IADLs.

CONCLUSION

ECF is a strong, significant, and independent correlate of functional status in normal aging. In contrast, decline in memory, as measured using the CVLT, has no independent association with the rate of change in functional status. This suggests that amnestic mild cognitive impairment can be associated with dementia only though the subsequent or comorbid development of ECF impairment.

Age-related differences in performance on the Wisconsin card sorting test: a meta-analytic review

Two meta-analyses investigating age-related differences in performance on a popular measure of executive function, the Wisconsin Card Sorting Test (WCST), are reported. The 1st meta-analysis examined age-related changes in performance for the number of categories achieved, and the 2nd meta-analysis examined performance for the number of perseverative errors committed. Results indicated that robust age differences were present on both measures. Further analysis of moderator variables revealed reliable effects of education and test version on both measures, whereas test modality led to marginally significant differences in effect sizes obtained only for the number of categories achieved. Findings are discussed along with current accounts of age differences in performance of the WCST.

Intellect declines in healthy elderly subjects and cerebellum

Scores of the performance scale of the Wechsler Adult Intelligence Scale (WAIS) declined linearly with age from the 6th decade, whereas those of the verbal scale did not. This decrease in performance intelligence was thought to be related to an age-related frontal atrophy. The relationship between scores of the WAIS and changes in regional cortical gray matter density were examined in healthy elderly subjects using voxel-based morphometry. Thirty healthy non-demented individuals >50 years of age were tested with the WAIS and scanned with brain magnetic resonance imaging (MRI). The right neocerebellum was significantly associated with scores of the performance intelligence scale while frontal lobes were not. The current study suggests that the cerebellum may play an important role in changes of intellectual capacity in old age.

Concept abstraction in the aging dog: development of a protocol using successive discrimination and size concept tasks

The present study examined the effects of age on concept learning in beagle dogs. In experiment one, subjects were tested on a series of 2-choice size discrimination (2CSD) tasks, in which the correct response was to always approach the larger or smaller of the two blocks. Compared to old and senior dogs, young and middle-aged dogs solved the initial training subtest faster and were more successful at transferring this learning to subsequent tests. The second experiment extended the task by using three rather than two objects and introducing novel objects to test concept acquisition. Young and middle-aged dogs made fewer errors than old or senior dogs on a 3-choice size discrimination (3CSD) task. Transfer performance was above chance for all four groups on the 3CSD and first 3-choice size concept (CSC) task and for the young dogs on the second 3CSC but did not differ from the original learning criterion in any group. Age impairments in concept learning may account for differences in transfer performance on both 3CSC tests.

Executive dyscontrol in normal aging: normative data, factor structure, and clinical correlates

Although there is ample evidence of frontal system dysfunction in old age, the clinical significance of these impairments has not been well studied. In this article, we examine the factor structure of putative executive measures in a sample of well elderly subjects. Three stable factors emerged, but only one was associated with measures of functional status. This factor was most strongly associated with relatively simple bedside executive measures that might prove useful in dementia screening. In contrast, a second factor, dominated by the Wisconsin Card Sorting Task, was weakly associated with disability. These data suggest that certain executive measures may be more relevant to functional outcomes, and hence dementia case finding, than others. Moreover, associations with functional status should not be casually extrapolated from regional frontal clinical correlations, particularly with the dorsolateral prefrontal cortex.

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

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

Decline in verbal memory performance with advancing age: the role of frontal lobe functioning

This study investigated the relationship between measures of frontal lobe functioning (FLF) and verbal memory performance among healthy, community-dwelling older adults (60-85 years old). All were administered measures of FLF, attention, verbal memory, and depression. After controlling for the effects of attention and depression, FLF accounted for significant amounts of the variance in verbal memory scores. Age related to the FLF measure according to the level of organization of verbal material to be recalled. Frontal lobe functioning and performance on an attention measure explained the greatest amount of the variance in the recall of unorganized verbal material, whereas age and attention abilities were the best predictors of the recall of organized verbal material. The data indicate a central role of frontal dysfunction in understanding age-related memory loss.

Differences in the functional neuroanatomy of inhibitory control across the adult life span

Inhibitory control, the ability to suppress irrelevant or interfering stimuli, is a fundamental cognitive function that deteriorates during aging, but little is understood about the bases of decline. Thus, we used event-related functional magnetic resonance imaging (fMRI) to study inhibitory control in healthy adults aged 18 to 78. Activation during "successful inhibition" occurred predominantly in right prefrontal and parietal regions and was more extensive, bilaterally and prefrontally, in the older groups. Presupplementary motor area was also more active in poorer inhibitory performers. Therefore, older adults activate areas that are comparable to those activated by young adults during inhibition, as well as additional regions. The results are consistent with a compensatory interpretation and extend the aging neuroimaging literature into the cognitive domain of inhibition.

Cerebral aging: neuropsychological, neuroradiological, and neurometabolic correlates

The aging process is associated with a progressive cognitive decline, but both the extent of this decline and the profile of age-related cognitive changes remain to be clearly established. Currently, cognitive deficits associated with aging may be diagnosed under the categories of age-associated memory impairment, age-associated cognitive impairment, or the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) category of age-related cognitive decline. Age-related decline has been reported for several cognitive domains, such as language (eg, verb naming, verbal fluency), visuospatial abilities (eg, facial discrimination), executive functions (eg, set shifting, problem solving), and memory functions (eg, declarative learning, source memory). There is an age-related decline in brain cortical volume, which primarily involves association cortices and limbic regions. Studies of brain metabolic activity demonstrate an age-related decline in neocortical areas. Activation studies using cognitive tasks demonstrate that older healthy individuals have a different pattern of activation from younger subjects, suggesting thai older subjects may recruit additional brain areas in order to maintain performance.

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

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

Frequency of perseveration in normal subjects

Although perseveration is a recognized sign of disturbed brain function, it also occurs in normal individuals. Determination of the frequency of perseveration in normal subjects would enable clinicians to use perseveration as a marker of possible pathology. The purpose of this study was to document the extent of perseveration in normal young and older subjects. Thirty young normal individuals between the ages of 20 and 35 years and 30 older normal individuals between the ages of 60 and 75 years were given four tasks on which perseveration has been reported in brain-damaged individuals. Four percent of all responses were perseverative. No age or gender effects on frequency were observed. Of the four neuropsychological tasks, the Modified Wisconsin Card Sorting Test elicited the greatest number of perseverations.

An overview of age-related changes in the scalp distribution of P3b

In this overview of 7 studies, the scalp distribution of the P3b component (i.e. the P3 or P300) of the event-related potential elicited by target events in young and older adults was assessed. The target P3b data were recorded in either auditory oddball paradigms or in visual study tasks in which orienting activity was manipulated (as a within-subjects variable) in investigations of indirect memory. Some of the studies required choice reaction time responses, whereas others required responses only to the target stimuli. Motor response requirements had a profound effect on the P3b scalp distribution of older but not of younger subjects. The presence of a frontally oriented scalp focus in the topographies of the older adults in most of the tasks described here is consistent with older adults continuing to use prefrontal processes for stimuli that should have already been well encoded and/or categorized. However, although older subjects generally had different P3b scalp distributions than younger subjects, their scalp distributions were modulated similarly by task requirements. These data suggest that similar mechanisms modulate the scalp distribution of P3b in older compared to younger adults. However, in the older adult, these scalp distribution changes in response to task demands are superimposed on a frontally oriented scalp focus due to a putative frontal lobe contribution to target P3b topography.