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PubMed2002

Performance on measures of executive function following pediatric traumatic brain injury.

OBJECTIVE: To investigate the relationships among age at injury, neuroanatomic lesion location, and measures of executive function (EF) following paediatric traumatic brain injury (TBI). METHODS: EF was assessed in 68 children (aged 7-15) with moderate-to-severe TBI 1 year post-injury. EF tests included: (1) Tower of Hanoi (TOH), a measure of problem solving ability, (2) Wisconsin Card Sorting Test (WCST), a measure of categorization and ability to shift cognitive strategies, (3) Letter Fluency (LF), a measure of novel lexical search and rule-governed word generation. EF variables included number of moves needed to achieve a 3-ring solution on the TOH, number of perseverative and non-perseverative errors on the WCST, and number of words generated on LF. Intellectual functioning was also assessed using the Verbal Intellectual Quotient (VIQ) from the Wechsler Intelligence Scale from Children-3rd edn (WISC-III). Data from standardized MRIs, performed at 3-months post-injury, were available for all subjects and were used to determine lesion location, lesion volumes, and total number of lesions. The relationships among EF, lesion variables (frontal lesion volume, extrafrontal lesion volume, total number of lesions) and age at injury were examined. Pre-injury special education services and attention deficit hyperactivity disorder (ADHD) were controlled for. RESULTS: Younger age at injury was associated with more perseverative errors on the WCST and worse performance on LF. Frontal lesion volume was not predictive of performance on any measures of EF. Greater extrafrontal lesion volume and total number of lesions were predictive of worse performance on LF. When controlling for pre-injury special education placement and pre-injury ADHD, there was little change in the results. CONCLUSIONS: Younger age at injury places children at greater risk of impairment on measures of EF. Performance on measures of EF depends on brain variables other than frontal lobes including extrafrontal cortical brain areas and total number of lesions. The relationship between extrafrontal brain regions and EF suggests that domain-specific cognitive content (i.e. language or visuospatial analysis), mediated by the parietal or temporal lobes, may disrupt underlying cognitive processes necessary for successful performance on measures of EF. In addition, the association between total number of lesions and EF may be related to disconnections and disruption of frontal/subcortical systems.

Adolescent↗

PubMed2003

A Canadian multicenter trial assessing memory and executive functions in patients with schizophrenia spectrum disorders treated with olanzapine.

Serial verbal learning task (explicit long-term memory) and verbal fluency (generation of a response) are tests that are usually severely impaired in schizophrenia. Despite the growing literature supporting the clinical efficacy of olanzapine, psychiatrists still question its cognitive consequences. This study assessed the efficacy of olanzapine on neurocognitive functioning. Patients (N = 134) meeting diagnostic criteria for schizophrenia, schizophreniform, or schizoaffective disorders began an 8-week, open-label olanzapine treatment at a dose of 5 mg/d, which was increased to 10 mg/d after 1 week. Daily dosage was subsequently adjusted between 5 and 20 mg/d based on individual clinical status. All previous antipsychotics were tapered and discontinued during the first 2 weeks of the study. Neuropsychologic assessments were carried out at baseline and at 4 and 8 weeks. Explicit long-term memory was assessed with the Rey Auditory-Verbal Learning Test: the average immediate recall score significantly improved (P < 0.001), as did the delayed recall score (P < 0.001). The average total score on category fluency improved from 34.6 words at baseline to 37.6 words at end point (P < 0.0001). Time on both Trail A and B making tasks significantly decreased (P < 0.0001). Lack of a control arm makes it impossible to exclude a practice effect as an explanation for the enhanced cognitive performance, although the Word List Recall test represents one of the better resources to avoid a practice effect. After switching to olanzapine, there was a statistically significant improvement of cognitive function in the 3 main domains tested and no significant worsening of any memory or executive function measure.

Acoustic Stimulation↗

PubMed1994

Executive function abilities in autism and Tourette syndrome: an information processing approach.

This study used information processing paradigms to provide a detailed examination of executive function abilities in autism. The performance of non-retarded autistic children was compared with that of two matched control groups, one with Tourette Syndrome and the other developmentally normal. Autistic subjects performed as well as controls on tasks requiring global-local processing and inhibition of neutral responses. In contrast to both control groups, however, the autistic sample was significantly impaired on a measure of cognitive flexibility. The performance of children with Tourette Syndrome did not differ from that of normal controls on any task. These results refine our knowledge about executive dysfunction in autism and suggest a new conceptual framework and general method for investigating the cognitive underpinnings of neurodevelopmental disorders.

Adolescent↗

PubMed1998

The ecological validity of tests of executive function.

Ninety-two mixed etiology neurological patients and 216 control participants were assessed on a range of neuropsychological tests, including 10 neuropsychological measures of executive function derived from 6 different tests. People who knew the patients well (relatives or carers) completed a questionnaire about the patient's dysexecutive problems in everyday life, and this paper reports the extent to which the tests predicted the patients' everyday life problems. All of the tests were significantly predictive of at least some of the behavioral and cognitive deficits reported by patients' carers. However, factor analysis of the patients' dysexecutive symptoms suggested a fractionation of the dysexecutive syndrome, with neuropsychological tests loading differentially on 3 underlying cognitive factors (Inhibition, Intentionality, and Executive Memory), supporting the conclusions that different tests measure different cognitive processes, and that there may be limits to the fractionation of the executive system.

Adult↗

PubMedDate not supplied

Executive functions and rehabilitation of the integrated self: a commentary on Ylvisaker and Feeney.

This commentary is a response to Ylvisaker and Feeney's paper "Executive functions, self-regulation and learned optimism in paediatric rehabilitation: a review and suggestions for intervention". Drawing on a diverse literature, the authors provide a broad empirical basis for a pragmatic approach to rehabilitation for children. Their contribution is critically reviewed in terms of the validity of their central thesis and the likely impact of their proposals. Although theoretically ambiguous in places and lacking the benefit of a truly developmental framework for intervention, their proposals, nevertheless, represent a coherent heuristic framework for teachers, clinicians and parents that has corollary implications for how paediatric rehabilitation is funded.

Child↗

PubMed2003

Executive functioning, temperament, and drug use involvement in adolescent females with a substance use disorder.

BACKGROUND: This study determined whether temperament mediates the relation between executive functioning (EF) and drug use involvement and whether EF and temperament interact to account for unique variance in drug use involvement. METHOD: Participants were 340, 14-18-year-old, adolescent females with a substance use disorder and controls. EF was measured using a battery of neuropsychological tests, temperament was assessed using the Dimensions of Temperament Survey--Revised, and drug use involvement was measured with the Drug Use Screening Inventory. RESULTS: Temperament mediated the relation between EF and drug use involvement. Girls with a 'difficult' temperament exhibited significantly greater drug use involvement than girls with a 'good' temperament. Finally, low EF was significantly related to increased drug use involvement for girls with a good temperament, but not for girls with a difficult temperament. CONCLUSIONS: The results suggest that a difficult temperament is a more important risk factor for drug use than low EF. Given previous studies that have shown significant relations between EF and drug use, further research on this topic is warranted.

Adolescent↗

PubMed2000

Heritability and the comorbidity of attention deficit hyperactivity disorder with behavioral disorders and executive function deficits: a preliminary investigation.

The heritability and comorbidity of attention deficit hyperactivity disorder (ADHD) with conduct disorder (CD), oppositional defiant disorder (ODD), and executive function (EF) deficits were examined in 224 child twins (140 monozygotic and 84 dizygotic). The Coolidge Personality and Neuropsychological Inventory for Children (Coolidge, 1998), a standardized, 200-item, Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) aligned, parent-as-respondent inventory, assessed psychopathology. Structural equation model fitting revealed that the individual scale heritabilities were substantial: .82 for ADHD, .74 for CD, .61 for ODD, and .77 for EF deficits. The results of the multivariate twin analyses suggest that ADHD shares most of its genetic liability with CD, ODD, and EF deficits. Thus, the findings argue for a common biological risk underlying these commonly comorbid externalizing behavior problems and cognitive deficits. The residual genetic variance provides preliminary support for additional genetic influences underlying CD, ODD, and EF that are independent of ADHD.

Adult↗

PubMed2000

Executive functioning, attention and frontal lesions in patients with chronic CHI.

To study the presence and nature of dysexecutive problems after CHI, a series of unstructured tasks tapping executive functioning were selected. These were administered to a group of 51 participants with CHI in the chronic stage (i.e. several years post-injury) and to 45 healthy controls. In addition, well-known structured tests of attention and planning were administered. Of the executive tasks, only the Executive Route Finding task showed a significant difference between both groups. A multivariate analysis on the attention tests showed a significant difference between groups, indicating that patients in the chronic stage still process information slower than controls. Within the patient group, patients with and without frontal focal lesions were also compared on executive and attention tests. No differences were found with respect to the latter. However, patients with frontal lesions performed worse on a measure of the Executive Route Finding task. It is concluded that patients with CHI, especially when they have frontal damage, have to rely more heavily on externally provided cues, but this dysexecutive problem can only be demonstrated in tasks that resemble daily life tasks by providing very little structure.

Adolescent↗

PubMed2003

The relationship between executive function and verbal memory in Parkinson's disease.

A growing body of evidence suggests that the various cognitive symptoms found in Parkinson's disease (PD) are secondary to executive dysfunction. Studies addressing this possibility for memory impairment specifically have not included measures of working memory nor have they ruled-out potential mediating variables such as overall level of cognitive impairment or depression. The purpose of this study was to include measures of these variables in determining the relationship between multiple aspects of executive function and delayed verbal recall in 32 idiopathic PD patients. Results were consistent with the original hypothesis and further suggest that working memory is a key factor in recall memory and may mediate the relationship between other executive measures and recall in PD.

Cognition Disorders↗

PubMed2002

Are central executive functions working in patients with focal frontal lesions?

The aim of this study was to examine the hypothesis of a link between frontal cortex and two executive functions in working memory: the capacity to perform a dual task and the ability to inhibit irrelevant information. A dual task designed to assess the capacity to perform storage and processing simultaneously and a directed forgetting task designed to assess the capacity to actively inhibit no-longer relevant information were administered to a group of patients with focal frontal lesions and to a group of control participants. The results revealed that despite showing reduced short-term storage, frontal patients performed the dual task and inhibited the no-longer relevant information as well as control participants. These findings suggest that not all-executive processes are exclusively sustained by the frontal cortex [Quart J Exp Psychol 9 (1996) 5; Curr Opin Neurobiol 10 (2000) 195; Neuropsychology (1994) 544; The Cognitive Neuropsychology of Alzheimer-type dementia. Oxford, New York: Oxford University Press, 1996].

Adult↗

PubMed2003

Psychometrically matched measures of global cognition, memory, and executive function for assessment of cognitive decline in older persons.

Item response theory methods were used to derive psychometrically sophisticated measures of global cognition, memory, and executive function. Goals were that these measures (a) could be derived from commonly used neuropsychological tests, (b) would have linear measurement properties, and (c) would be psychometrically matched. Scale development was based on a sample of 400 older individuals with cognitive function ranging from normal to demented. Scales were reasonably matched with linear measurement over an ability range relevant to many important clinical applications. Cognitively normal, mild impairment, and dementia participant groups differed on baseline measures and rate of decline. Association of measures with quantitative structural magnetic resonance imaging variables followed expected patterns. This approach to scale development may have applications for other neuropsychological assessment problems.

Aged↗

PubMed1998

The Tower of London(DX): a standardized approach to assessing executive functioning in children.

In the current study, the Tower of London (Shallice, 1982) was modified to enhance its clinical utility as a measure of childhood executive functioning. The Tower of London-Drexel (TOL(DX)) was administered to normal control (NC; N = 56) and attention-deficit hyperactivity disorder (ADHD; N = 99) children (ages 7 to 12) to determine whether age-related changes in performance were evident, to gather normative data, and to evaluate the test-retest reliability and criterion-validity of the measure. The results revealed age-related changes in score performance, age-group normative data, an acceptable level of reliability and significant differences in performance of NC and ADHD subjects. Further, discriminant analysis classification rates determined that the TOL(DX) was sensitive and highly specific to ADHD. Implications and limitations of the study are discussed.

Journal Article↗

PubMedDate not supplied

Prospective memory and executive function in schizophrenia.

Experimental studies of normal subjects have shown that the intention to perform an action speeds word recognition for items related to that intention (Goschke & Kuhl, 1993). This phenomenon--the intention superiority effect (ISE)--is thought to be mediated by frontal executive functions. Since schizophrenia is characteristically associated with forms of frontal-executive dysfunction, an impaired ISE might be expected in this patient group. A script-learning paradigm was used to investigate the ISE in 10 schizophrenics who do show evidence of executive dysfunction and in 10 who do not. As predicted, only the former showed an ISE; however, all schizophrenics showed an ISE to words semantically related to the intention. It seems that the ability to form specific intentions is impaired only in schizophrenics with executive dysfunction; however, they retain the ability to form more generalized intentions.

Adult↗

PubMed1997

Executive function and uptake of 99mTc-exametazime shown by single photon emission tomography after oral idazoxan in probable Alzheimer-type dementia.

Preliminary reports suggest improved executive function in patients with lobar dementia after treatment with single doses of the alpha 2 adrenoceptor antagonist, idazoxan. The potential for use in probable Alzheimer-type dementia prompted the present study. Fifteen patients with probable Alzheimer-type dementia were examined twice with neuropsychological measures and 14 also with single photon emission tomography (SPET) after a single double blind oral administration of 40 mg idazoxan or placebo in a balanced cross-over design. Brain perfusion maps were spatially transformed into standard stereotactic space and compared pixel-by-pixel. A parametric analysis was used to examine the relationship between the drug effect, verbal fluency and brain perfusion. Two to 3 h after idazoxan, measures of reaction time, Stroop test, category fluency and anxiety were unchanged. Verbal fluency (letter) and spatial working memory were impaired and performance on the Tower of London test in a sub-set of patients showed a trend to impairment in the idazoxan condition. Idazoxan produced a modest relative activation in left thalamus and inferior occipital cortex: decreases occurred in inferior anterior cingulate and left insular cortex. There were significant correlations on both days between measures of fluency and brain perfusion in left lateral prefrontal cortex. The reduced performance with idazoxan was directly correlated with reduced perfusion in left lateral prefrontal cortex, supporting an important interaction between drug and task performance. The imaging component of the study therefore suggested that activation of frontal networks is necessary for performing fluency tasks in Alzheimer-type dementia. Brain networks involving prefrontal cortex are the locus for the primary cognitive effects of noradrenergic drugs. The direction of the effect of any dose of agonist or antagonist may depend critically upon the age and pathology of the experimental subjects and the relationship between performance, noradrenergic drive and task difficulty.

Adrenergic alpha-Antagonists↗

PubMed2003

Task-set switching deficits in early-stage Huntington's disease: implications for basal ganglia function.

Executive functions are likely mediated by interconnected circuits including frontal lobe and basal ganglia structures. We assessed the executive function of task switching in patients with early-stage Huntington's disease (HD), a neurodegenerative disease affecting the basal ganglia. In two experiments, the HD patients had greater difficulty when switching than when repeating a task than matched controls, and this was true even when scaling for the overall slowing of the patients. In the first experiment, HD patients had a switching deficit even in a "pure" condition where they had to switch, predictably, and with substantial preparation time, between stimuli having only one possible response, indicating a switching deficit different from that for patients with Parkinson's disease or frontal lobe trauma, and possibly relating to inadequate activation of stimulus-response links or "response set." In the more elaborate second experiment, we could not account for the switching deficit of the patients in terms of inadequate preparation in advance of a switch, deficient suppression of task-set processing from the preswitch trial, or impaired suppression of interference due to the presence of a competing task set. Instead, we found that part of the switching deficit was due to elevated reaction time and errors on switch trials for a repeated response (same button press as on preswitch trial) relative to an alternated response (different button press from preswitch trial). We argue that this elevated "repetition effect" for the HD patients is due to excessive inhibition of the just-performed response in advance of a switch. Alterations in the "response-setting" process alone (Experiment 1) and both the response-setting and "response inhibition" process (Experiment 2) probably arise from striatal pathology in HD, thus accounting for the task-switching deficits and showing how basal ganglia implemented response processes may underpin executive function.

Adult↗

PubMed1999

Executive function in depression: the role of performance strategies in aiding depressed and non-depressed participants.

OBJECTIVES: Depression has been found to be associated with dysfunction in executive processes, whereas relatively automatic processes are thought to remain intact. Failure to generate or implement adequate performance strategies has been postulated in depressed participants. The present study investigated spontaneous strategy usage in depressed and control participants, and the effectiveness of providing a hint about performance strategies. METHODS: Unipolar depressed participants were compared with matched healthy controls on three tasks sensitive to executive function: memory for categorised words, response suppression, and multiple scheduling. Participants in each group were randomly allocated to strategy aid and no strategy aid conditions. Those in the strategy aid condition were given a hint about the use of an appropriate performance strategy for each task, in addition to the standard instructions given to those in the no strategy aid condition. RESULTS: Depressed participants performed worse than controls on each of the three tasks, and were found to use appropriate performance strategies less often. Provision of strategy hints increased the use of performance strategies in two of the three tasks, memory for categorised words, and response suppression, but did not significantly improve overall performance for either group. CONCLUSIONS: The findings were consistent with the view that depressed participants fail to use appropriate performance strategies spontaneously to the same extent as controls. However, provision of information alone does not seem to be an adequate means of enhancing performance. The role of performance strategies in cognitive impairment in depression is discussed, both in terms of initiating use of such strategies and carrying these out efficiently.

Adult↗

PubMed2003

Switching attention and resolving interference: fMRI measures of executive functions.

Is there a single executive process or are there multiple executive processes that work together towards the same goal in some task? In these experiments, we use counter switching and response inhibition tasks to examine the neural underpinnings of two cognitive processes that have often been identified as potential executive processes: the switching of attention between tasks, and the resolution of interference between competing task responses. Using functional magnetic resonance imaging (fMRI), for both event-related and blocked design tasks, we find evidence for common neural areas across both tasks in bilateral parietal cortex (BA 40), left dorsolateral prefrontal cortex (DLPFC; BA 9), premotor cortex (BA 6) and medial frontal cortex (BA 6/32). However, we also find areas preferentially involved in the switching of attention between mental counts (BA 7, BA 18) and the inhibition of a prepotent motor response (BA 6, BA 10), respectively. These findings provide evidence for the separability of cognitive processes underlying executive control.

Adolescent↗

PubMed1995

Executive functions of the frontal lobes: psychometric properties of a self-rating scale.

This study investigated the psychometric properties of a self-rating scale designed to test the executive functions of the frontal lobes. A set of 16 items was selected, based on face validity, from the 200-item Coolidge Axis II Inventory. Cronbach scale reliability for the new scale was .72 on 1,223 purportedly normal participants. A factor analysis yielded a three-factor structure, Decision-making difficulties (8 items, 23% of the variance, scale reliability .77), Poor planning (4 items, 15% of the variance, scale reliability .63), and Task incompletion (6 items, 9% of the variance, scale reliability .66). A multivariate analysis of variance, performed on the overall scale sum and the three subscales, between 17 closed head-injured patients and a matched control group was significant. The head-injured patients scored significantly higher on the over-all measure of executive dysfunction and higher on the decision-making difficulties subscale but not on the other two subscales.

Adolescent↗