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

Occupational health, cognitive disorders and occupational neuropsychology

Work can be an important etiologic factor in the genesis of some mental disorders including cognitive disability. Occupational neuropsychology constitutes an intriguing new but neglected area of research and clinical practice which deals with the neurocognitive consequences of the work environment and work habits. Neuropsychological knowledge is fundamental to understand cognitive requirements of work competence. Work can impact sleep patterns and mental energy, which in turn can cause neuropsychological symptoms. This report presents relevant evidence to illustrate the relationship between work and cognitive dysfunction.

Structural integrity of the corpus callosum predicts long-term transfer of fluid intelligence-related training gains in normal aging

Although cognitive training usually improves cognitive test performance, the capability to transfer these training gains into respective or functionally related cognitive domains varies significantly. Since most studies demonstrate rather limited transfer effects in older adults, aging might be an important factor in transfer capability differences. This study investigated the transfer capability of logical reasoning training gains to a measure of Fluid Intelligence (Gf) in relation to age, general intelligence, and brain structural integrity as measured by diffusion tensor imaging. In a group of 41 highly educated healthy elderly, 71% demonstrated successful transfer immediately after a 4-week training session (i.e. short-term transfer). In a subgroup of 22% of subjects transfer maintained over a 3-month follow-up period (i.e. long-term transfer). While short-term transfer was not related to structural integrity, long-term transfer was associated with increased structural integrity in corpus and genu of the corpus callosum. Since callosal structural integrity was also related to age (in the present and foregoing studies), previously observed associations between age and transfer might be moderated by the structural integrity. Surprisingly, age was not directly associated with transfer in this study which could be explained by the multi-dependency of the structural integrity (modulating factors beside age, e.g. genetics). In this highly educated sample, general intelligence was not related to transfer suggesting that high intelligence is not sufficient for transfer in normal aging. Further studies are needed to reveal the interaction of transfer, age, and structural integrity and delineate mechanisms of age-dependent transfer capabilities.

Executive dysfunction and treatment response in late-life depression

OBJECTIVES

Executive dysfunction in geriatric depression has been shown to predict poor response to antidepressant medication. The purpose of this review is to clarify which aspects of executive functioning predict poor antidepressant treatment response.

METHODS

Literature review.

RESULTS

From our review, the aspects of executive functioning that appear to be associated with antidepressant response rates are verbal fluency and response inhibition. There is some indication that the semantic strategy component may account for the effects of verbal fluency, although evidence comes from one study and needs replication. Processing speed has been proposed as a substrate that may underlie the effects of executive dysfunction on treatment response. Although processing speed does not appear to account for the relationship between response inhibition and treatment outcome, this issue has yet to be assessed with respect to verbal fluency.

CONCLUSIONS

Verbal fluency and response inhibition are specific aspects of executive dysfunction that appear to impact antidepressant response rates. Disruption of the frontostriatal limbic circuit (particularly the anterior cingulate and dorsolateral prefrontal cortex) may explain the relation between these two mechanisms.

Childhood executive function continues to predict outcomes in young adult females with and without childhood-diagnosed ADHD

We prospectively followed an ethnically and socioeconomically diverse sample of preadolescent girls with ADHD (n = 140) and matched comparison girls (n = 88) over a period of 10 years, from middle childhood through late adolescence/young adulthood. Our aim was to examine the ability of childhood measures of executive function (EF) to predict functional outcomes at follow-up. Measures of EF comprised the childhood predictors, with academic, socioemotional, occupational, and global functioning serving as young adult criterion measures. Results indicated that childhood EF - particularly measures of global EF and working memory - predicted academic and occupational functioning across our entire sample (independent of diagnostic group status), but diagnostic status (ADHD versus comparison) moderated the association between (a) working memory and reading achievement and (b) a global EF measure and suspensions/expulsions. That is, in the ADHD group, low working memory predicted poor reading scores and impaired global EF predicted higher suspensions/expulsions, but this was not the case in the comparison group. Overall, these results extend previous findings of associations between EF and adolescent outcomes in girls with and without ADHD into young adulthood. Findings continue to suggest the importance of assessing and developing interventions that target EF impairments early in life in order to prevent long-term difficulties across a range of important functional domains.

Do traditional executive measures tell us anything about daily-life functioning after traumatic brain injury in Spanish-speaking individuals?

PRIMARY OBJECTIVE

To examine the relationship between traditional executive function measures and everyday competence in Spanish-speaking individuals with moderate-to-severe traumatic brain injury (TBI).

METHODS AND PROCEDURES

Thirty-two TBI patients (24 men, eight women) with an age range of 17-59 years (mean age = 30.73 years; SD = 13.34) were administered a battery of performance-based executive function measures. Such measures included the Trail Making Test part B, Wisconsin Card Sorting Test, Stroop Colour Word Interference Test, Controlled Oral Word Association Test and Letter-Number Sequencing. Behavioural manifestations of executive deficits were assessed by the Behaviour Rating Inventory of Executive Function-Adult version (BRIEF-A). Patient's everyday functioning was examined with the Patient Competency Rating Scale (PCRS).

MAIN OUTCOMES AND RESULTS

Traditional performance-based executive measures correlated significantly, although moderately, with the PCRS; this relationship was more significant in the Controlled Oral Word Association Test and Trail Making Test part B. A significant correlation was obtained between the BRIEF-A clinical scales and patient's everyday competence as measured by the PCRS.

CONCLUSIONS

The current findings suggest that traditional performance-based executive measures reveal some degree of ecological validity or real-world relevance, providing relevant information for predicting everyday competence after moderate-to-severe TBI.

Tavistock Adult Depression Study (TADS): a randomised controlled trial of psychoanalytic psychotherapy for treatment-resistant/treatment-refractory forms of depression

BACKGROUND

Long-term forms of depression represent a significant mental health problem for which there is a lack of effective evidence-based treatment. This study aims to produce findings about the effectiveness of psychoanalytic psychotherapy in patients with treatment-resistant/treatment-refractory depression and to deepen the understanding of this complex form of depression.

METHODS/DESIGN INDEX GROUP

Patients with treatment resistant/treatment refractory depression.

DEFINITION & INCLUSION CRITERIA

Current major depressive disorder, 2 years history of depression, a minimum of two failed treatment attempts, ≥14 on the HRSD or ≥21 on the BDI-II, plus complex personality and/or psycho-social difficulties.

EXCLUSION CRITERIA

Moderate or severe learning disability, psychotic illness, bipolar disorder, substance dependency or receipt of test intervention in the previous two years.

DESIGN

Pragmatic, randomised controlled trial with qualitative and clinical components.

TEST INTERVENTION

18 months of weekly psychoanalytic psychotherapy, manualised and fidelity-assessed using the Psychotherapy Process Q-Sort.

CONTROL CONDITION

Treatment as usual, managed by the referring practitioner.

RECRUITMENT

GP referrals from primary care.

RCT MAIN OUTCOME

HRSD (with ≤14 as remission).

SECONDARY OUTCOMES

depression severity (BDI-II), degree of co-morbid disorders Axis-I and Axis-II (SCID-I and SCID-II-PQ), quality of life and functioning (GAF, CORE, Q-les-Q), object relations (PROQ2a), Cost-effectiveness analysis (CSRI and GP medical records).

FOLLOW-UP

2 years. Plus: a). Qualitative study of participants' and therapists' problem formulation, experience of treatment and of participation in trial. (b) Narrative data from semi-structured pre/post psychodynamic interviews to produce prototypes of responders and non-responders. (c) Clinical case-studies of sub-types of TRD and of change.

DISCUSSION

TRD needs complex, long-term intervention and extended research follow-up for the proper evaluation of treatment outcome. This pushes at the limits of the design of randomised therapeutic trials. We discuss some of the consequent problems and suggest how they may be mitigated.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN40586372.

Cognitive impairment in heart failure

Cognitive impairment (CI) is increasingly recognized as a common adverse consequence of heart failure (HF). Although the exact mechanisms remain unclear, microembolism, chronic or intermittent cerebral hypoperfusion, and/or impaired cerebral vessel reactivity that lead to cerebral hypoxia and ischemic brain damage seem to underlie the development of CI in HF. Cognitive decline in HF is characterized by deficits in one or more cognition domains, including attention, memory, executive function, and psychomotor speed. These deficits may affect patients' decision-making capacity and interfere with their ability to comply with treatment requirements, recognize and self-manage disease worsening symptoms. CI may have fluctuations in severity over time, improve with effective HF treatment or progress to dementia. CI is independently associated with disability, mortality, and decreased quality of life of HF patients. It is essential therefore for health professionals in their routine evaluations of HF patients to become familiar with assessment of cognitive performance using standardized screening instruments. Future studies should focus on elucidating the mechanisms that underlie CI in HF and establishing preventive strategies and treatment approaches.

Frontal brain asymmetry in depression with comorbid anxiety: a neuropsychological investigation

The approach-withdrawal model posits that depression and anxiety are associated with a relative right asymmetry in frontal brain activity. Most studies have tested this model using measures of cortical brain activity such as electroencephalography. However, neuropsychological tasks that differentially use left versus right frontal cortical regions can also be used to test hypotheses from the model. In two independent samples (Study 1 and 2), the present study investigated the performance of currently depressed individuals with or without a comorbid anxiety disorder and healthy controls on neuropsychological tasks tapping primarily left (verbal fluency) or right (design fluency) frontal brain regions. Across both samples, results indicated that comorbid participants performed more poorly than depressed only and control participants on design fluency, while all groups showed equivalent performance on verbal fluency. Moreover, comorbid participants showed "asymmetrical" performance on these two tasks (i.e., poorer design [right frontal] relative to verbal [left frontal] fluency), whereas depressed only and control participants showed approximately symmetrical profiles of performance. Results from these two samples suggest an abnormal frontal asymmetry in neurocognitive performance driven primarily by right frontal dysfunction among anxious-depressed individuals and highlight the importance of considering comorbid anxiety when examining frontal brain functioning in depression.

Verbal fluency and awareness of functional deficits in early-stage dementia

Assessment of activities of daily living is an important element in the diagnosis of dementia, with research suggesting a link between functional ability and cognition. We investigated the relationship between self- and informant ratings of instrumental activities of daily living (iADL) and verbal executive functioning in early-stage dementia. A total of 96 people with early-stage Alzheimer's disease or vascular or mixed dementia and their carers completed the Functional Activities Questionnaire; people with dementia also completed a test of letter fluency. Letter fluency was associated with self-ratings of iADL, while informant ratings of iADL were associated with the age and Mini-Mental State Examination score of the person with dementia. Self-ratings of perceived functioning suggested significantly less impairment than informant ratings. Those with impaired letter fluency rated themselves as having greater difficulties in iADLs than those who performed better. People with early-stage dementia vary in their subjective level of awareness of their iADL functioning, and difficulties with language production may contribute to better awareness of iADL impairments.

Processing speed and executive functions in cognitive aging: how to disentangle their mutual relationship?

The processing-speedtheory and the prefrontal-executivetheory are competing theories of cognitive aging. Here we used a theoretically and methodologically-driven framework to investigate the relationships among measures classically used to assess these two theoretical constructs. Twenty-eight young adults (18-32 years) and 39 healthy older adults (65-80 years) performed a battery of nine neuropsychological and experimental tasks assessing three executive function (EF) components: Inhibition, Updating, and Shifting. Rate of information processing was evaluated via three different experimental and psychometric tests. Partial correlations analyses suggested that 2-Choice Reaction Time (CRT) performance is a more pure measure of processing speed than Digit Symbol Substitution Test (DSST) performance in the elderly. Hierarchical regression analyses showed that, although measures of processing speed and EF components share mutual variance, each measure was independently affected by chronological age. The unique adverse effect of age was more important for processing speed than for EF. The processing-speed theory and the prefrontal-executive theory of cognitive aging were shown not to be mutually exclusive but share mutual variance. This implies the need to control for their mutual relationship before examining their unique potential role in the explanation of age-related cognitive declines. Caution has still to be taken concerning the tasks used to evaluate these theoretical constructs.

Executive function and type 2 diabetes: putting the pieces together

The devastating impact of type 2 diabetes mellitus (DM) on vascular, renal, retinal, and peripheral nerve functions has been well documented. However, there is also evidence that older adults with this disease exhibit impairments in the planning, coordinating, sequencing, and monitoring of cognitive operations, collectively known as executive function. Although poorly understood, disturbances in executive function, particularly within the dimension of time sharing, may contribute to the gait abnormalities and increased risk for falls, functional impairments, and disabilities associated with type 2 DM. However, the relationships between executive function and functional abilities remain poorly understood in this population. Current neuropsychological research regarding the concept of executive function is presented here as a framework upon which to examine the integrity of this critical cognitive entity in adults with type 2 DM. The pathophysiological mechanisms thought to underlie diabetes-related executive dysfunction are explored, and the possible contributions of executive deficits to impairments in gait and function observed in older people with type 2 DM are summarized. Finally, a brief discussion of dual-task assessment and intervention strategies that may facilitate the care and rehabilitation of the growing population of patients with type 2 DM is provided.

The profile of executive function in very preterm children at 4 to 12 years

AIM

To examine executive functioning in very preterm (gestational age ≤30 wks) children at 4 to 12 years of age.

METHOD

Two-hundred very preterm (106 males, 94 females; mean gestational age 28.1wks, SD 1.4; mean age 8y 2mo, SD 2y 6mo) and 230 term children (106 males, 124 females; mean gestational age 39.9wks, SD 1.2; mean age 8y 4mo, SD 2y 3mo) without severe disabilities, born between 1996 and 2004, were assessed on an executive function battery comprising response inhibition, interference control, switching, verbal fluency, verbal and spatial working memory, and planning. Multiple regression analyses examined group differences while adjusting for effects of parental education, age, sex, and speed indices.

RESULTS

Relative to children born at term, very preterm children had significant (p(s) <0.02; where p(s) represents p-values) deficits in verbal fluency (0.5 standardized mean differences [SMD]), response inhibition (0.4 SMD), planning (0.4 SMD), and verbal and spatial working memory (0.3 SMD), independent of slow and highly fluctuating processing speed. A significant group by age interaction indicated that group differences for response inhibition decreased between 4 and 12 years.

INTERPRETATION

Very preterm birth is associated with a profile of affected and non-affected executive functions independent of impaired speed. Deficits are of small to moderate magnitude and persist over time, except for response inhibition for which very preterm children catch up with peers.

Executive functions and self-regulation

Self-regulation is a core aspect of adaptive human behavior that has been studied, largely in parallel, through the lenses of social and personality psychology as well as cognitive psychology. Here, we argue for more communication between these disciplines and highlight recent research that speaks to their connection. We outline how basic facets of executive functioning (working memory operations, behavioral inhibition, and task-switching) may subserve successful self-regulation. We also argue that temporary reductions in executive functions underlie many of the situational risk factors identified in the social psychological research on self-regulation and review recent evidence that the training of executive functions holds significant potential for improving poor self-regulation in problem populations.

The Nature and Organization of Individual Differences in Executive Functions: Four General Conclusions

Executive functions (EFs)-a set of general-purpose control processes that regulate one's thoughts and behaviors-have become a popular research topic lately and have been studied in many subdisciplines of psychological science. This article summarizes the EF research that our group has conducted to understand the nature of individual differences in EFs and their cognitive and biological underpinnings. In the context of a new theoretical framework that we have been developing (the unity/diversity framework), we describe four general conclusions that have emerged from our research. Specifically, we argue that individual differences in EFs, as measured with simple laboratory tasks, (1) show both unity and diversity (different EFs are correlated yet separable); (2) reflect substantial genetic contributions; (3) are related to various clinically and societally important phenomena; and (4) show some developmental stability.

Parent ratings of executive functioning in children with shunted hydrocephalus

OBJECTIVES

The present study examined the executive functioning of a group of children with a history of communicating hydrocephalus and how their level of functioning was correlated with parent ratings of executive functioning.

METHODS

The study examined the executive functioning of 39 shunted children with a history of hydrocephalus and 20 healthy peers. Additionally, parents of both groups of children completed the Behavior Rating Inventory of Executive Function (BRIEF) to assess the parents' perceptions of their children's executive functioning. Finally, the study investigated the relationship between the shunted hydrocephalus children's executive functioning and the parent ratings of their executive functioning.

RESULTS

Overall, the children with a history of shunted hydrocephalus displayed more executive dysfunction than their healthy peers. These children were rated by their parents as having more executive dysfunction than their healthy peers and displaying working memory, initiation, mental flexibility and self-monitoring difficulties, which appear to increase with age among the shunted hydrocephalus group. While parent ratings as measured by the BRIEF indices did not correlate with all executive tasks within the shunted hydrocephalus group, the cognitive tests assessing mental flexibility may be sensitive to the problems noted by parents at home.

CONCLUSIONS

The children with a history of shunted hydrocephalus displayed executive functioning deficits on formal examination. The parents of children with a history of shunted hydrocephalus report ongoing executive difficulties which may increase with age.

Decision-making heuristics and biases across the life span

We outline a contextual and motivational model of judgment and decision-making (JDM) biases across the life span. Our model focuses on abilities and skills that correspond to deliberative, experiential, and affective decision-making processes. We review research that addresses links between JDM biases and these processes as represented by individual differences in specific abilities and skills (e.g., fluid and crystallized intelligence, executive functioning, emotion regulation, personality traits). We focus on two JDM biases-the sunk-cost fallacy (SCF) and the framing effect. We trace the developmental trajectory of each bias from preschool through middle childhood, adolescence, early adulthood, and later adulthood. We conclude that life-span developmental trajectories differ depending on the bias investigated. Existing research suggests relative stability in the framing effect across the life span and decreases in the SCF with age, including in later life. We highlight directions for future research on JDM biases across the life span, emphasizing the need for process-oriented research and research that increases our understanding of JDM biases in people's everyday lives.

Impaired cognitive inhibition in schizophrenia: a meta-analysis of the Stroop interference effect

Schizophrenia has been consistently shown to be associated with impairment in executive functioning. However, although frequently treated as such, the term executive functioning does not refer to a unitary cognitive function; it rather represents a set of basic, lower-level cognitive sub-components, e.g. updating, shifting, and cognitive inhibition. This specification into sub-components allows for a further differentiation of the executive deficits found in schizophrenia. Focusing on the sub-component of cognitive inhibition, we here present a meta-analysis of interference effect as assessed with the Stroop Color-Word Interference paradigm. Including the results of 36 studies with 1081 schizophrenia patients and 1026 healthy control subjects, it was shown that schizophrenia patients exhibit an increased Stroop interference effect both in response time (mean effect size: M(g) = 0.43; 95% confidence interval, CI95%: 0.35-0.52) and accuracy (M(g) = 0.62; CI95%: 0.47-0.77) measures of interference. However, a meta-regression analysis revealed that the size of the effect varies depending on the version of the Stroop paradigm used. Regarding the response time measures of interference, studies using the classical card version of the paradigm showed a significantly larger effect size than studies using a single-trial computerized version of the paradigm (M(g) = 0.60 vs. M(g) = 0.19). Despite of the dissociation between the two versions of the paradigm, the results of the present meta-analysis indicate that the reported global deficits in executive functioning found to be associated with schizophrenia are at least partly due to a reduced ability of cognitive inhibition.

The Role of Representations in Executive Function: Investigating a Developmental Link between Flexibility and Abstraction

Young children often perseverate, engaging in previously correct, but no longer appropriate behaviors. One account posits that such perseveration results from the use of stimulus-specific representations of a situation, which are distinct from abstract, generalizable representations that support flexible behavior. Previous findings supported this account, demonstrating that only children who flexibly switch between rules could generalize their behavior to novel stimuli. However, this link between flexibility and generalization might reflect general cognitive abilities, or depend upon similarities across the measures or their temporal order. The current work examined these issues by testing the specificity and generality of this link. In two experiments with 3-year-old children, flexibility was measured in terms of switching between rules in a card-sorting task, while abstraction was measured in terms of selecting which stimulus did not belong in an odd-one-out task. The link between flexibility and abstraction was general across (1) abstraction dimensions similar to or different from those in the card-sorting task and (2) abstraction tasks that preceded or followed the switching task. Good performance on abstraction and flexibility measures did not extend to all cognitive tasks, including an IQ measure, and dissociated from children's ability to gaze at the correct stimulus in the odd-one-out task, suggesting that the link between flexibility and abstraction is specific to such measures, rather than reflecting general abilities that affect all tasks. We interpret these results in terms of the role that developing prefrontal cortical regions play in processes such as working memory, which can support both flexibility and abstraction.

The relationship between gross motor skills and academic achievement in children with learning disabilities

The present study compared the gross motor skills of 7- to 12-year-old children with learning disabilities (n = 104) with those of age-matched typically developing children (n = 104) using the Test of Gross Motor Development-2. Additionally, the specific relationships between subsets of gross motor skills and academic performance in reading, spelling, and mathematics were examined in children with learning disabilities. As expected, the children with learning disabilities scored poorer on both the locomotor and object-control subtests than their typically developing peers. Furthermore, in children with learning disabilities a specific relationship was observed between reading and locomotor skills and a trend was found for a relationship between mathematics and object-control skills: the larger children's learning lag, the poorer their motor skill scores. This study stresses the importance of specific interventions facilitating both motor and academic abilities.

Impact of prenatal exposure to cocaine and tobacco on diffusion tensor imaging and sensation seeking in adolescents

OBJECTIVE

To study white matter integrity with diffusion tensor imaging in adolescents with prenatal cocaine exposure, tobacco exposure, or both.

STUDY DESIGN

Subjects included 20 adolescents with prenatal cocaine exposure (15 with tobacco exposure) and 20 non-cocaine-exposed subjects (8 with tobacco exposure). Diffusion tensor imaging measures were assessed in 5 subregions of the corpus callosum. The Sensation Seeking Scale for Children was administered to evaluate behavioral inhibition.

RESULTS

No significant differences were found between the cocaine-exposed and non-cocaine-exposed groups in each subregion of the corpus callosum on measures of fractional anisotropy (FA) and mean diffusivity, although the cocaine-exposed group showed a trend (P = .06) toward higher FA in projections to the supplementary motor area and premotor cortex. Prenatal tobacco exposure was associated with decreased FA in the supplementary motor area and premotor cortex projections after adjustment for relevant co-variates (P = .03). Decreased FA was related to more sensation seeking in the adolescents who were prenatally exposed to tobacco.

CONCLUSION

Prenatal tobacco exposure could affect white matter integrity, which is related to sensation seeking in adolescents. Developmental neurotoxins might have differential influences on white matter maturation in adolescence.

Executive functions in Parkinson's disease: systematic review and meta-analysis

Impairment of executive function (EF) is commonly reported as a feature of PD. However, the exact pattern of executive impairment remains unclear. Also, there is an ongoing discussion surrounding the definition and conceptualization of EF, which might affect the clarity of research evidence on cognition in PD. The aim of this systematic review was to describe the pattern of executive impairment in early-stage PD emerging from the research literature and to identify critical issues for improving consistency in this field. The PsychInfo, MEDLINE, Science Direct, CINAHL, and Cochrane Library databases were searched using the term "Parkinson's disease" combined with each of 14 cognitive abilities defined as representing aspects of EF. The review was limited to studies that investigated EF as the central variable in early-stage, nondemented PD patients. The review identified 33 studies of EF that were operationalized in terms of 30 abilities tested by 60 measures and variously interpreted. Many measures were used only once, so only a small part of the available research evidence could be synthesized in the meta-analysis. The meta-analysis was undertaken using data from five commonly used tests of EF drawn from 18 studies. This revealed consistent evidence for cognitive difficulties across all five EF tests. Research on EF in PD is characterized by a considerable lack of clarity with regard to measure selection and interpretation. The findings support the view that EF impairments are evident in PD. However, the clinical significance of the cognitive abnormalities reported has yet to be clarified.

Acute glucocorticoid effects on the multicomponent model of working memory

OBJECTIVE

In comparison with basal physiological levels, acute, high levels of cortisol affect learning and memory. Despite reports of cortisol-induced episodic memory effects, no study has used a comprehensive battery of tests to evaluate glucocorticoid effects on the multicomponent model of working memory. Here, we report the results of a double-blind, placebo-controlled, between-subjects study.

METHODS

Twenty healthy young men were randomly assigned to either acute cortisol (30 mg hydrocortisone) or placebo administration. Participants were subjected to an extensive cognitive test battery that evaluated all systems of the multicomponent model of working memory, including various executive domains (shifting, updating, inhibition, planning and access to long-term memory).

RESULTS

Compared with placebo, hydrocortisone administration increased cortisol blood levels and impaired working memory in storage of multimodal information in the episodic buffer and maintenance/reverberation of information in the phonological loop. Hydrocortisone also decreased performance in planning and inhibition tasks, the latter having been explained by changes in storage of information in working memory.

CONCLUSIONS

Thus, hydrocortisone acutely impairs various components of working memory, including executive functioning. This effect must be considered when administering similar drugs, which are widely used for the treatment of many clinical disorders.

Compulsivity predicts fronto striatal activation in severely anorectic individuals

Anorexia nervosa is a severe illness and shows one of the highest death rates among psychiatric or psychosomatic diseases. However, despite several lines of research, the etiology of this disease is still unknown. One of those features is the rigidity of behaviors, for example, controlling of weight and pursuing of thinness, that often meets the criteria for obsessive-compulsive behavior. In this study, it was investigated whether the clinical feature of compulsivity in anorexia nervosa patients relates to regional brain activation. Using functional magnetic resonance imaging, 12 severely anorectic women were compared to 12 normal-weight female individuals following a cue-reactivity paradigm. Cues comprised food cues of high and low calorie content as well as eating-related utensils. Voxel-based morphometric analysis indicated significantly overall reduced gray matter volume and significantly increased cerebrospinal fluids in anorexia nervosa (AN) patients, which was controlled for in subsequent analyses. Following the high-calorie stimulation, AN patients activated the right caudate body and right precuneus, whereas control subjects did not show significant regional activations. In both other conditions, low-calorie foods and eating utensils, regional brain activations did not survive FDR thresholds. During the high-calorie condition, compulsivity, that is, the subscore "obsessive thoughts," predicted activation of the superior frontal gyrus [Brodmann areas (BA) 10], inferior frontal gyrus, anterior cingulate cortex (BA 32), cingulate gyrus (BA 24), caudate body, cuneus, pre- and postcentral gyrus. The subscore "compulsive acts" correlated with activation of the claustrum during the high-calorie condition and predicted a number of deactivations of frontal and temporal regions. We conclude that in severely anorectic individuals, the degree of compulsivity predicts activation and deactivation of the fronto-striatal pathway.

Patterns of cognitive performance in healthy ageing in Northern Portugal: a cross-sectional analysis

BACKGROUND

The Minho Integrative Neuroscience Database (MIND)-Ageing project aims to identify predictors of healthy cognitive ageing, including socio-demographic factors. In this exploratory analysis we sought to establish baseline cohorts for longitudinal assessment of age-related changes in cognition.

METHODS

The population sample (472 individuals) was strictly a convenient one, but similar to the Portuguese population in the age profile. Participants older than 55 years of age were included if they did not present defined disabling pathologies or dementia. A standardized clinical interview was conducted to assess medical history and a battery of neuropsychological tests was administered to characterize global cognition (Mini Mental State Examination), memory and executive functions (Selective Reminding Test; Stroop Color and Word Test; and Block Design subtest of the Wechsler Adult Intelligence Scale). Cross-sectional analysis of the neuropsychological performance with individual characteristics such as age, gender, educational level and setting (retirement home, senior university, day care center or community), allowed the establishment of baseline clusters for subsequent longitudinal studies.

RESULTS

Based on different socio-demographic characteristics, four main clusters that group distinctive patterns of cognitive performance were identified. The type of institution where the elders were sampled from, together with the level of formal education, were the major hierarchal factors for individual distribution in the four clusters. Of notice, education seems to delay the cognitive decline that is associated with age in all clusters.

CONCLUSIONS

Social-inclusion/engagement and education seem to have a protective effect on mental ageing, although this effect may not be effective in the eldest elders.

Cognitive control in adults with attention-deficit/hyperactivity disorder

The objective of the present study was to investigate the ability of adults with Attention-Deficit/Hyperactivity Disorder (ADHD) to direct their attention and exert cognitive control in a forced instruction dichotic listening (DL) task. The performance of 29 adults with ADHD was compared with 58 matched controls from the Bergen Dichotic Listening Database (N>1500). Participants in the Bergen DL task listen to and report from conflicting consonant-vowel combinations (two different syllables presented simultaneously, one to each ear). They are asked to report the syllable they hear (non-forced condition), or to focus and report either the right- or left-ear syllable (forced-right and forced-left condition). This procedure is presumed to tap distinct cognitive processes: perception (non-forced condition), orienting of attention (forced-right condition), and cognitive control (forced-left condition). Adults with ADHD did not show significant impairment in the conditions tapping perception and attention orientation, but were significantly impaired in their ability to report the left-ear syllable during the forced-left instruction condition, whereas the control group showed the expected left-ear advantage in this condition. This supports the hypothesis of a deficit in cognitive control in the ADHD group, presumably mediated by a deficit in a prefrontal neuronal circuitry. Our results may have implications for psychosocial adjustment for persons with ADHD in educational and work environments.

Animal Verbal Fluency and Design Fluency in school-aged children: effects of age, sex, and mean level of parental education, and regression-based normative data

The Animal Verbal Fluency (AVF) and Design Fluency (DF) structured and unstructured test versions were administered to N = 294 healthy native Dutch-speaking children who were aged between 6.56 and 15.85 years. The AVF and DF structured test scores increased linearly as a function of age, whilst the relation between age and the DF unstructured test score was curvilinear (i.e., the improvement in test scores was much more pronounced for younger children than for older children). A higher mean level of parental education was associated with significantly higher AVF and DF structured test scores. Sex was not associated with any of the outcomes. Demographically corrected norms for the AVF and DF tests were established, and an automatic scoring program was provided.

Detecting subtle changes in visuospatial executive function and learning in the amnestic variant of mild cognitive impairment

BACKGROUND AND PURPOSE

Amnestic mild cognitive impairment (aMCI) is a putative prodromal stage of Alzheimer's disease (AD) characterized by deficits in episodic verbal memory. Our goal in the present study was to determine whether executive dysfunction may also be detectable in individuals diagnosed with aMCI.

METHODS

This study used a hidden maze learning test to characterize component processes of visuospatial executive function and learning in a sample of 62 individuals with aMCI compared with 94 healthy controls.

RESULTS

Relative to controls, individuals with aMCI made more exploratory/learning errors (Cohen's d = .41). Comparison of learning curves revealed that the slope between the first two of five learning trials was four times as steep for controls than for individuals with aMCI (Cohen's d = .64). Individuals with aMCI also made a significantly greater number of rule-break/error monitoring errors across learning trials (Cohen's d = .21).

CONCLUSIONS

These results suggest that performance on a task of complex visuospatial executive function is compromised in individuals with aMCI, and likely explained by reductions in initial strategy formulation during early visual learning and "on-line" maintenance of task rules.

Inhibition and shifting capacities mediate adults' age-related differences in strategy selection and repertoire

Young and older adults differ in how many strategies they use to accomplish cognitive tasks. They also differ in how often they select the best strategy on each problem. Two experiments were run to determine whether two executive functions-inhibition and shifting capacities-mediate age-related differences in strategy repertoire and in strategy selection. Both experiments were run in arithmetic problem solving. In Experiment 1, young and older adults' strategy repertoire was assessed on a problem-by-problem basis while participants solved two-digit addition problems (e.g., 42+76). In Experiment 2, young and older participants had to select the best strategy on each problem to find estimates of two-digit multiplication problems (e.g., 43×72). In both experiments, individuals' inhibition and shifting capacities were assessed with the Trail Making Test and the Stroop Test. The main results showed that (a) older adults used a smaller strategy repertoire (Expt. 1) and selected the best strategy on each problem less frequently (Expt. 2) than young adults, (b) inhibition and shifting capacities mediated age-related differences in strategy repertoire and strategy selection, and unique age effects were no longer significant in strategy repertoire but were still significant in strategy selection after statistical control of inhibition and shifting capacities. We discuss important implications of these findings to further our understanding of strategic variations during cognitive aging.

Criterion and construct validity of the CogState Schizophrenia Battery in Japanese patients with schizophrenia

Background

The CogState Schizophrenia Battery (CSB), a computerized cognitive battery, covers all the same cognitive domains as the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery but is briefer to conduct. The aim of the present study was to evaluate the criterion and construct validity of the Japanese language version of the CSB (CSB-J) in Japanese patients with schizophrenia.

Methodology/Principal Findings

Forty Japanese patients with schizophrenia and 40 Japanese healthy controls with matching age, gender, and premorbid intelligence quotient were enrolled. The CSB-J and the Brief Assessment of Cognition in Schizophrenia, Japanese-language version (BACS-J) were performed once. The structure of the CSB-J was also evaluated by a factor analysis. Similar to the BACS-J, the CSB-J was sensitive to cognitive impairment in Japanese patients with schizophrenia. Furthermore, there was a significant positive correlation between the CSB-J composite score and the BACS-J composite score. A factor analysis showed a three-factor model consisting of memory, speed, and social cognition factors.

Conclusions/Significance

This study suggests that the CSB-J is a useful and rapid automatically administered computerized battery for assessing broad cognitive domains in Japanese patients with schizophrenia.

Integrating situated learning theory and neuropsychological research to facilitate patient participation and learning in traumatic brain injury rehabilitation patients

PURPOSE

Traumatic brain injury (TBI) constitutes a major health problem throughout the world. Despite interdisciplinary efforts, patients reach varying outcomes in terms of every-day life functioning and quality-of-life. This paper suggests that a situated learning perspective supplemented with evidence from neurophysiologic and neuropsychological research provides a perspective to get a grasp of problems typically encountered in rehabilitation. Applying such a perspective may help to facilitate patient participation and learning during the rehabilitation process by taking their altered abilities into consideration.

METHOD

Qualitative study. Theoretical analysis and synthesis of 'situated learning theory', neuropsychological theory and empirical studies of cognitive and emotional functioning following a TBI collected through interviews with 11 interdisciplinary rehabilitation experts and a field study of two patients at a rehabilitation hospital. The data were analysed from a hermeneutic perspective using N-VIVO 8.

RESULTS/CONCLUSION

Patients with severe TBI pose challenges in terms of being participants in the 'rehabilitation practice community'. Two levels of pedagogical challenges seem to exist: Helping the patient regain or compensate for changed learning abilities and supporting the patient in learning or compensating for lost abilities. This study highlighted six main categories of changed abilities that need to be considered in developing a practice which fosters re-learning: perception, attention, memory, language, physical competencies and emotion/model of behaviour.

Are gross motor skills and sports participation related in children with intellectual disabilities?

This study compared the specific gross motor skills of 156 children with intellectual disabilities (ID) (50 ≤ IQ ≥ 79) with that of 255 typically developing children, aged 7-12 years. Additionally, the relationship between the specific gross motor skills and organized sports participation was examined in both groups. The Test of Gross Motor Development-2 and a self-report measure were used to assess children's gross motor skills and sports participation, respectively. The children with ID scored significantly lower on almost all specific motor skill items than the typically developing children. Children with mild ID scored lower on the locomotor skills than children with borderline ID. Furthermore, we found in all groups that children with higher object-control scores participated more in organized sports than children with lower object-control scores. Our results support the importance of attention for well-developed gross motor skills in children with borderline and mild ID, especially to object-control skills, which might contribute positively to their sports participation.

Early adolescent executive functioning, intrauterine exposures and own drug use

Individual differences in adolescents' executive functioning are often attributed either to intrauterine substance exposure or to adolescents' own substance use, but both predictors typically have not been evaluated simultaneously in the same study. This prospective study evaluated whether intrauterine drug exposures, the adolescents' own substance use, and/or their potential interactions are related to poorer executive functioning after controlling for important contextual variables. Analyses were based on data collected on a sample of 137 predominantly African-American/African Caribbean adolescents from low-income urban backgrounds who were followed since their term birth. Intrauterine substance exposures (cocaine, marijuana, alcohol, and cigarettes) and adolescents' substance use were documented using a combination of biological assays and maternal and adolescent self-report. At 12-14 years of age, examiners masked to intrauterine exposures and current substance use assessed the adolescents using the Delis-Kaplan Executive Function System (D-KEFS), an age-referenced instrument evaluating multiple dimensions of executive functioning (EF). Results of covariate-controlled analyses in this study suggest that when intrauterine substance exposures and young adolescents' substance use variables were in the same analysis models, subtle differences in specific EF outcomes were identifiable in this non-referred sample. While further study with larger samples is indicated, these findings suggest that 1) research on adolescent substance use and intrauterine exposure research should evaluate both predictors simultaneously, 2) subtle neurocognitive effects associated with specific intrauterine drug exposures can be identified during early adolescence, and 3) intrauterine substance exposure effects may differ from those associated with adolescents' own drug use.

Socioeconomic gradients and child development in a very low income population: evidence from Madagascar

Our objectives were to document and examine socioeconomic gradients across a comprehensive set of child development measures in a population living in extreme poverty, and to interpret these gradients in light of findings from the neuroscience literature. We assessed a nationally representative sample of 3-6-year-old children (n = 1332) from 150 communities of Madagascar using standard tests of development. We found that children whose families were in the top wealth quintile or whose mothers had secondary education performed significantly better across almost all measures of cognitive and language development and had better linear growth compared with children of women in the lowest wealth quintile or women with no education. These differences between children of low and high socioeconomic position were greatest for receptive language, working memory, and memory of phrases. The mean difference in the scores between children in the highest and lowest socioeconomic status categories doubled between age 3 and age 6, and the biggest gaps across socioeconomic position by age 6 were in receptive language and sustained attention. Our results suggest that even within the context of extreme poverty, there are strong associations between family socioeconomic status and child development outcomes among preschool children, and that the language and executive function domains exhibit the largest gradients.