Changes In Executive Function Research Articles

DIFFUSION TENSOR IMAGE SEGMENTATION OF THE CEREBRUM PROVIDES A SINGLE MEASURE OF CEREBRAL SMALL-VESSEL DISEASE SEVERITY RELATED TO COGNITIVE CHANGE

Cerebral small vessel disease (SVD) is the primary cause of vascular cognitive impairment and is associated with decline in executive function (EF) and information processing speed (IPS). Imaging biomarkers are needed that can monitor and identify individuals at risk of severe cognitive decline. Recently there has been interest in combining several magnetic resonance imaging (MRI) markers of SVD into a unitary score to describe disease severity. Here we apply a diffusion tensor image (DTI) segmentation technique (DSEG) to describe SVD related changes in a single unitary score across the whole cerebrum, to investigate its relationship with cognitive change over a three-year period. 98 patients (aged 43-89) with SVD underwent annual MRI scanning and cognitive testing for up to three years. DSEG provides a vector of 16 discrete segments describing brain microstructure of healthy and/or damaged tissue. By calculating the scalar product of each DSEG vector in reference to that of a healthy ageing control we generate an angular measure (DSEG θ) describing the patients' brain tissue microstructural similarity to a disease free model of a healthy ageing brain. Conventional MRI markers of SVD brain change were also assessed including white matter hyperintensities, cerebral atrophy, incident lacunes, cerebral-microbleeds, and white matter microstructural damage measured by DTI histogram parameters. The impact of brain change on cognition was explored using linear mixed-effects models. Post-hoc sample size analysis was used to assess the viability of DSEG θ as a tool for clinical trials. Changes in brain structure described by DSEG θ were related to change in EF and IPS (p < 0.001) and remained significant in multivariate models including other MRI markers of SVD as well as age, gender and premorbid IQ. Of the conventional markers, presence of new lacunes was the only marker to remain a significant predictor of change in EF and IPS in the multivariate models (p = 0.002). Change in DSEG θ was also related to change in all other MRI markers (p < 0.017), suggesting it may be used as a surrogate marker of SVD damage across the cerebrum. Sample size estimates indicated that fewer patients would be required to detect treatment effects using DSEG θ compared to conventional MRI and DTI markers of SVD severity. DSEG θ is a powerful tool for characterising subtle brain change in SVD that has a negative impact on cognition and remains a significant predictor of cognitive change when other MRI markers of brain change are accounted for. DSEG provides an automatic segmentation of the whole cerebrum that is sensitive to a range of SVD related structural changes and successfully predicts cognitive change. Power analysis shows DSEG θ has potential as a monitoring tool in clinical trials. As such it may provide a marker of SVD severity from a single imaging modality (i.e. DTIs).

Attachment Security and Developmental Patterns of Growth in Executive Functioning During Early Elementary School.

Despite the extensive research demonstrating the importance of child executive functioning (EF) for school adjustment, little longitudinal work has formally examined developmental change in EF during the early school years. Based on a sample of 106 mother-child dyads, the current longitudinal study investigated patterns of growth in child performance on three executive tasks between kindergarten (Mage =6years) and Grade 3 (Mage =9years), and the predictive role of earlier mother-child attachment security in these patterns. The results suggest that early elementary school is a period of significant developmental improvement in child EF, although child performance on different EF tasks follows distinct trajectories across time. The study also provides evidence for a sustained relation between children's early attachment security and their ongoing acquisition of executive skills.

Teacher Evaluations of Executive Functioning in Schoolchildren Aged 9-12 and the Influence of Age, Sex, Level of Parental Education.

Executive functions (EFs) develop over the period of early childhood and adolescence up until young adulthood. Individual children differ substantially in the pace at which their EFs develop, and characteristics such as sex and the level of parental education (LPE) are thought to contribute to these differences. In the present study, we assessed age-related changes in EFs as perceived and evaluated by teachers and parents as well as the influence of sex and LPE on their evaluations. We used a newly developed observer-report questionnaire, the Amsterdam Executive Function Inventory (AEFI). The AEFI assesses three important components of the executive aspects of daily life behavior in 13 questions: Attention; Self-control and Self-monitoring; and Planning and Initiative taking. Teachers and parents evaluated these aspects of executive functioning in 186 schoolchildren in grades 3–6 (age: 9–12 years). Age effects within grades and differences in social economic status between the four participating schools were controlled. Results showed a significant increase in teacher-perceived EFs from third to fourth grades and from fifth to sixth grades. This development was influenced both by the sex of the child and by the LPE. As perceived by teachers, the component self-control and self-monitoring was higher for girls than for boys, and planning abilities were higher for children from families with a higher LPE. Additional analyses showed that there is a systematic and statistically significant difference between the evaluations of the teachers and that of parents. Parents reported higher scores for planning, whereas teachers reported higher scores for self-control and self-monitoring. Evaluations by parents and teachers were different for girls, but not for boys. These findings are important because they imply that the development of EFs as perceived by parents and teachers is influenced by child-related factors. Second, there are clear differences in evaluations between teachers and parents. The AEFI appears to be a tool that is easily used by parents and teachers and shows potential for monitoring the development of EFs as perceived by significant others during young adolescence.

Diffusion tensor image segmentation of the cerebrum provides a single measure of cerebral small vessel disease severity related to cognitive change.

Cerebral small vessel disease (SVD) is the primary cause of vascular cognitive impairment and is associated with decline in executive function (EF) and information processing speed (IPS). Imaging biomarkers are needed that can monitor and identify individuals at risk of severe cognitive decline. Recently there has been interest in combining several magnetic resonance imaging (MRI) markers of SVD into a unitary score to describe disease severity. Here we apply a diffusion tensor image (DTI) segmentation technique (DSEG) to describe SVD related changes in a single unitary score across the whole cerebrum, to investigate its relationship with cognitive change over a three-year period.98 patients (aged 43–89) with SVD underwent annual MRI scanning and cognitive testing for up to three years. DSEG provides a vector of 16 discrete segments describing brain microstructure of healthy and/or damaged tissue. By calculating the scalar product of each DSEG vector in reference to that of a healthy ageing control we generate an angular measure (DSEG θ) describing the patients' brain tissue microstructural similarity to a disease free model of a healthy ageing brain. Conventional MRI markers of SVD brain change were also assessed including white matter hyperintensities, cerebral atrophy, incident lacunes, cerebral-microbleeds, and white matter microstructural damage measured by DTI histogram parameters. The impact of brain change on cognition was explored using linear mixed-effects models. Post-hoc sample size analysis was used to assess the viability of DSEG θ as a tool for clinical trials.Changes in brain structure described by DSEG θ were related to change in EF and IPS (p < 0.001) and remained significant in multivariate models including other MRI markers of SVD as well as age, gender and premorbid IQ. Of the conventional markers, presence of new lacunes was the only marker to remain a significant predictor of change in EF and IPS in the multivariate models (p = 0.002). Change in DSEG θ was also related to change in all other MRI markers (p < 0.017), suggesting it may be used as a surrogate marker of SVD damage across the cerebrum. Sample size estimates indicated that fewer patients would be required to detect treatment effects using DSEG θ compared to conventional MRI and DTI markers of SVD severity.DSEG θ is a powerful tool for characterising subtle brain change in SVD that has a negative impact on cognition and remains a significant predictor of cognitive change when other MRI markers of brain change are accounted for. DSEG provides an automatic segmentation of the whole cerebrum that is sensitive to a range of SVD related structural changes and successfully predicts cognitive change. Power analysis shows DSEG θ has potential as a monitoring tool in clinical trials. As such it may provide a marker of SVD severity from a single imaging modality (i.e. DTIs).

Independent value added by diffusion MRI for prediction of cognitive function in older adults.

The purpose of this study was to determine whether white matter microstructure measured by diffusion magnetic resonance imaging (dMRI) provides independent information about baseline level or change in executive function (EF) or memory (MEM) in older adults with and without cognitive impairment. Longitudinal data was acquired from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study from phases GO and 2 (2009–2015). ADNI participants included were diagnosed as cognitively normal (n = 46), early mild cognitive impairment (MCI) (n = 48), late MCI (n = 29), and dementia (n = 39) at baseline. We modeled the association between dMRI-based global white matter mean diffusivity (MD) and baseline level and change in EF and MEM composite scores, in models controlling for baseline bilateral hippocampal volume, regional cerebral FDG PET metabolism and global cerebral AV45 PET uptake. EF and MEM composite scores were measured at baseline, 6, 12, 24 and 36 months. In the baseline late MCI and dementia groups, greater global MD was associated with lesser baseline EF, but not EF change nor MEM baseline or change. As expected, lesser hippocampal volume and lesser FDG PET metabolism was associated with greater rates of EF and MEM decline. In ADNI-GO/2 participants, white matter integrity provided independent information about current executive function, but was not sensitive to future cognitive change. Since individuals experiencing executive function declines progress to dementia more rapidly than those with only memory impairment, better biomarkers of future executive function decline are needed.

Randomized controlled trial of a web-based multi-modal therapy program for executive functioning in children and adolescents with unilateral cerebral palsy

Purpose state: Determine the efficacy of Move-it-to-improve-it (Mitii™), a multi-modal web-based program, in improving Executive Function (EF) in children with unilateral cerebral palsy (UCP).Method: Participants (n = 102) were matched in pairs then randomized to: intervention (Mitii™ for 20 weeks; n = 51; 26 males; mean age = 11 years 8 months (SD = 2 years 4 months); Full Scale IQ = 84.65 (SD = 15.19); 28 left UCP; GMFCS-E&R (I = 20, II = 31) or waitlist control (n = 50; 25 males; mean age = 11 years 10 months (SD = 2 years 5 months); Full Scale IQ = 80.75 (SD = 19.81); 20 left UCP; GMFCS-E&R (I = 25, II = 25). Mitii™ targeted working memory (WM), visual processing (VP), upper limb co-ordination and physical activity. EF capacity was assessed: attentional control (DSB; WISC-IV); cognitive flexibility (inhibition and number-letter sequencing DKEFS); goal setting (D-KEFs Tower Test); and information processing (WISC-IV Symbol Search and Coding). EF performance was assessed via parent report (BRIEF). Groups were compared at 20 weeks using linear regression (SPSS 21).Results: There were no significant between group differences in attentional control (DSB; p = 0.20;CI= −0.40,1.87); cognitive flexibility (Inhibition, p = 0.34; CI= −0.73,2.11; number/letter sequencing, p = 0.17; CI= −0.55,2.94); problem solving (Tower; p = 0.28; CI= −0.61,2.09), information processing (Symbol; p = 0.08; CI= −0.16, 2.75; Coding; p = 0.07; CI= −0.12,2.52) or EF performance (p = 0.13; CI= −10.04,1.38).Conclusion:In a large RCT, MitiiTM did not lead to significant improvements on measures of EF or parent ratings of EF performance in children with UCP.Implications for rehabilitationA large RCT of the multi-modal web based training; Move It to Improve It (MitiiTM) improves motor processing, visual perception, and physical capacity but does demonstrate statistically significant improvements or clinical significance in executive function in children with mild to moderate unilateral cerebral palsy (UCP).MitiiTM training completed by an intervention group was highly variable with few children reaching the target dosage of 60 h. Technical issues including server and internet connectively problems lead to disengagement with the program.Web-based training delivered in the home has the potential to increase therapy dose and accessibility, however, MitiiTM needs to be tailored to include tasks involving goal-setting, more complex problem solving using multi-dimensional strategies, mental flexibility, switching between two cognitively demanding tasks, and greater novelty in order to increase the cognitive component and challenge required to drive changes in EF.

Executive function mediates prospective relationships between sleep duration and sedentary behavior in children

Childhood sedentary behavior has been linked to increased obesity risk. Prior work has identified associations between sedentary behavior, executive function (EF), and sleep. This study tested the hypothesis that reduced sleep duration may adversely impact EF and lead to increased childhood sedentary behavior. Southern California schoolchildren participating in the school-based health promotion program Pathways to Health (N=709) were assessed annually from 4th through 6th grades (2010−2013) on self-report measures of sedentary behavior, sleep duration, and executive function. A series of path models were specified treating average nightly sleep duration and weekend wake/bed-time shift at 4th grade as predictors of 6th grade sedentary behavior. Four EF subdomains were tested as potential mediators of longitudinal associations at 5th grade. Significant associations between average nightly sleep duration, EF and sedentary behavior were identified (p<0.05), adjusting for participant gender, physical activity, SES, ethnicity, program group assignment, and the presence/absence of parental screen time rules. Fifth grade overall EF (p<0.05)—and in particular the subdomains of inhibitory control (p<0.05) and organization of materials (p<0.01)—significantly mediated the relationship between 4th grade sleep duration and 6th grade sedentary behavior (p<0.05). Furthermore, delay of weekend bed- or wake-times relative to weekdays was prospectively associated with decreased overall EF (p<0.05), but not increased sedentary behavior (p=0.35 for bed-time delay; p=0.64 for wake-time delay), irrespective of average nightly sleep duration. Findings suggest that sleep promotion efforts may reduce children's sedentary behavior both directly and indirectly through changes in EF.

Exploring the influence of socioeconomic status on the executive function and theory of mind skills of preschoolers

EXPLORING THE INFLUENCE OF SOCIOECONOMIC STATUS ON THE EXECUTIVE FUNCTION AND THEORY OF MIND SKILLS OF PRESCHOOLERS By Andrea Molzhon, M.S. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2016. Director: Geraldine Lotze, Ph.D., Associate Professor, Department of Psychology Executive function (EF) and theory of mind (ToM) skills develop rapidly during the preschool years and have been found to directly and indirectly contribute to school readiness. Evidence indicates that EF may influence ToM development, though this relation may not be consistent across children from different backgrounds. Additionally, socioeconomic status (SES) has been shown to affect preschoolers’ EF, while the literature is mixed regarding the effects – if any – that SES may have on ToM development. Though the relation between EF and ToM appears robust across the literature, the possible effects of SES on this relation have yet to be fully explored. As children from low-SES homes are more likely to fall behind at the start of school, and this achievement gap is likely to widen through the school years, it is important to understand how the cognitive components that contribute to school readiness develop and are affected by SES so that we may work toward improving preschool education for children across all socioeconomic backgrounds. The primary purpose of the current study was to determine whether SES affected the relation between EF and ToM among urban preschool children (ages 35 years) from various SES backgrounds. In addition to examining the EF-ToM relation, relations among SES, general cognitive skills, EF, and ToM, as well as relations among age, EF, and ToM, were examined. Results from correlational and regression analyses indicated that SES was related to EF but not ToM, and that EF was not related to ToM after controlling for age. Inconsistent with the majority of previous findings, the results did not support the hypothesized link between EF and ToM. However, the findings from this study do add support to the large body of literature pertaining to the positive relation between SES and EF, and provide evidence that ToM may be relatively protected from the negative effects of low-SES among preschoolers. Results also support previous reports of large age-related changes in EF and ToM that occur during the preschool years. The implications for preschool development and education are discussed.

The contribution of children’s time-specific and longitudinal expressive language skills on developmental trajectories of executive function

To investigate whether children’s early language skills support the development of executive functions (EFs), the current study used an epidemiological sample (N=1121) to determine whether two key language indicators, vocabulary and language complexity, were predictive of EF abilities over the preschool years. We examined vocabulary and language complexity both as time-varying covariates that predicted time-specific indicators of EF at 36 and 60 months of age and as time-invariant covariates that predicted children’s EF at 60 months and change in EF from 36 to 60 months. We found that the rate of change in children’s vocabulary between 15 and 36 months was associated with both the trajectory of EF from 36 to 60 months and the resulting abilities at 60 months. In contrast, children’s language complexity had a time-specific association with EF only at 60 months. These findings suggest that children’s early gains in vocabulary may be particularly relevant for emerging EF abilities.

Repeated high-intensity interval exercise shortens the positive effect on executive function during post-exercise recovery in healthy young males

A single bout of aerobic exercise improves executive function (EF), but only for a short period. Compared with a single bout of aerobic exercise, we recently found that high-intensity interval exercise (HIIE) could maintain a longer improvement in EF. However, the mechanism underlying the effect of different exercise modes on the modifications of EF remains unclear. The purpose of the current investigation was to test our hypothesis that the amount of exercise-induced lactate production and its accumulation affects human brain function during and after exercise, thereby affecting post-exercise EF. Ten healthy male subjects performed cycle ergometer exercise. The HIIE protocol consisted of four 4-min bouts at 90% peak VO2 with a 3-min active recovery period at 60% peak VO2. The amount of lactate produced during exercise was manipulated by repeating the HIIE twice with a resting period of 60min between the 1st HIIE and 2nd HIIE. To evaluate EF, a color-word Stroop task was performed, and reverse-Stroop interference scores were obtained. EF immediately after the 1st HIIE was significantly improved compared to that before exercise, and the improved EF was sustained during 40min of the post-exercise recovery. However, for the 2nd HIIE, the improved EF was sustained for only 10min of the post-exercise recovery period, despite the performance of the same exercise. In addition, during and following HIIE, the glucose and lactate accumulation induced by the 2nd HIIE was significantly lower than that induced by the 1st HIIE. Furthermore, there was an inverse relationship between lactate and EF by plotting the changes in lactate levels against changes in EF from pre-exercise during the late phase of post-exercise recovery. These findings suggested the possibility that repeated bouts of HIIE, which decreases lactate accumulation, may dampen the positive effect of exercise on EF during the post-exercise recovery.

Risk-reducing Apolipoprotein E and Clusterin genotypes protect against the consequences of poor vascular health on executive function performance and change in nondemented older adults

We examined independent and cumulative effects of 2 Alzheimer's-related genetic polymorphisms, Apolipoprotein E (APOE) and Clusterin (CLU), in relation to the deleterious effects of poor vascular health (pulse pressure [PP]) on executive function (EF) performance and change in nondemented older adults. Using a sample (n = 593; age range = 53–95 years) from the Victoria Longitudinal Study, we applied latent growth modeling to test the effect of PP, as moderated by APOE and CLU, on an EF latent variable. EF was affected by higher levels of PP but differentially less so for carriers of low-risk alleles (APOE ɛ2+; CLU TT) than for moderate- or high-risk alleles (APOE ɛ2−; CLU C+). The cumulative genetic risk of APOE plus CLU provided similar moderation of PP level effects on EF. Future research may focus on how APOE and CLU might provide different but complementary contributions to predicting EF level and change. Vascular health risk in synergistic association with risk-related polymorphisms can elucidate the neurobiological underpinnings of cognitive trajectories in nondemented aging.

Stability and change in executive function abilities from late adolescence to early adulthood: A longitudinal twin study.

Executive functions (EFs)-the higher level cognitive abilities that enable us to control our own thoughts and actions-continue to develop into early adulthood, yet no longitudinal study has examined their stability during the important life transition from late adolescence to young adulthood. In this twin study (total N = 840 individuals from 424 families), we examined the stability of individual differences in 3 EF components across a 6-year period, from approximately age 17 years (Wave 1) to 23 years (Wave 2). Specifically, we address the following questions: (a) How stable are individual differences in multiple EFs across this time period? and (b) What (genetic and/or environmental) influences affect stability and change in EFs? Results indicated that individual differences in EFs are quite stable across this 6-year period (phenotypic latent variable correlations ranged from 0.86 to 1.0). However, there was evidence for change, particularly in the factor common to multiple EFs (Common EF). Multivariate twin models suggested that stability was due almost entirely to high genetic correlations across time; there was no new genetic variance at Wave 2. Change in Common EF was due to small but significant nonshared environmental influences at Wave 2 (15%). The results suggest that individual differences in EFs are quite heritable and stable by late adolescence, yet are still sensitive to environmental influences.

Executive Function in Low Birth Weight Preschoolers: The Moderating Effect of Parenting.

Previous meta-analyses have identified moderate deficits in executive function (EF) in children born low birth weight (birth weight < 2500 g; LBW). The current study tests the joint contribution of LBW and parenting quality on trajectories of executive function in 1121 preschoolers (50 % boys). We estimated latent growth curve models to represent linear change in EF from 3 to 5 years of age, and tested the impact of LBW, parenting, and their interaction, on the estimated trajectory parameters. Although LBW was related to lower EF ability at all three time points (Cohen's d = 0.43-0.55), LBW children who experienced high levels of sensitive parenting in toddlerhood exhibited faster rates of improvement in EF, and were virtually indistinguishable from their normal birth weight peers by age 5. On the other hand, LBW children who experienced below average levels of sensitive parenting showed lasting deficits in EF ability. These findings suggest that sensitive parenting may buffer LBW children from lasting deficits in EF. Implications of these findings for future interventions are discussed.

Association of the apolipoprotein E genotype with memory performance and executive functioning in cognitively intact elderly.

To test for a possible effect of the apolipoprotein E epsilon 4 (APOE ε4) allele on memory performance and executive functioning (EF) in cognitively intact elderly. The authors studied 202 randomly selected and cognitively intact older adults (65+ years) of the Leipzig Research Center for Civilization Diseases Health Care Study. Intact global cognitive functioning was defined using a Mini-Mental Status Examination (MMSE) score ≥ 28. Performance in memory was assessed with the CERAD Word List and Constructional Praxis Recall, performance in EF with the Trail Making Test Part B (TMT-B). Multivariable linear regressions were used to evaluate the association between cognitive performance and APOE status, controlled for covariates. Among the cognitively intact older adults, 21.3% (n = 43) were carriers of the APOE ε4 allele. Carriers did not differ significantly from noncarriers in terms of age, gender, intelligence level, or performance in memory but showed a significantly lower TMT-B performance as a measure of EF (TMT-B M time/SD = 105.6/36.2 vs. 91.9/32.7 s; Mann-Whitney U = 4,313.000; p = .009). The association between lower TMT-B performance and APOE ε4 genotype remained significant in multivariable linear regression analysis. Similar findings were found for the subsample of those 78 elderly, who reached a perfect MMSE-score of 30. A lower EF performance in cognitively intact older APOE ε4 allele carriers might be related to an early Alzheimer's dementia (AD) prodrome. In this case, a stronger focus on first subtle changes in EF may help to improve early AD detection in those being at genetic risk.

Executive function and self-regulated exergaming adherence among older adults.

The rise in dementia and the evidence of cognitive benefits of exercise for the older adult population together make salient the research into variables affecting cognitive benefit and exercise behavior. One promising avenue for increasing exercise participation has been the introduction of exergaming, a type of exercise that works in combination with virtual reality to enhance both the exercise experience and health outcomes. Past research has revealed that executive function (EF) was related to greater use of self-regulatory strategies, which in turn was related to greater adherence to exercise following an intervention (McAuley et al., 2011). Best et al. (2014) found improvement in EF related to adherence to exercise post- intervention. Anderson-Hanley et al. (2012) found that for older adults aerobic exergaming yielded greater cognitive benefit than traditional exercise alone; however, questions remain as to the possible impact of greater cognitive benefit and other factors on participants’ involvement in exercise following the end of an intervention. The current study presents follow-up data exploring the relationship between EF, self-regulation, and exercise behavior in the post-intervention (naturalistic) period. Herein, it was predicted that higher EF at the start of the naturalistic window, would predict subsequent exercise with an exergame. Contrary to expectations, results suggest that those with poorer EF are likely to exergame more frequently. The results of this study contradict previous literature, but suggest an interesting relationship between EF, self-regulation, and exercise behaviors when exergaming is employed, particularly with older adults with some cognitive decline. We hypothesize that other factors may be at work, perhaps expectation of cognitive benefit might act as a unique motivator.

Executive Function Deficits in Daily Life Prospectively Predict Increases in Depressive Symptoms.

Executive function (EF) deficits are associated with depression. Given that few prospective studies have been conducted, it is unclear whether deficits contribute to depression or result from it. The present study examined whether self-reported EF prospectively predicted worsening of depression symptoms. Time 1 (T1) shifting, inhibition, and working memory (WM) were assessed in relation to T1 and time 2 (T2) depressive symptoms in participants pre-selected to range in risk for depression. Analyses indicated that poorer EF at T1 predicted increases in depressive symptoms and furthermore that this relationship was specific to WM. In contrast, a bidirectional relationship was not evident, as depressive symptoms did not prospectively predict changes in EF. Finally, T1 EF accounted for T2 depressive symptoms beyond two well established predictors of depression: depressive symptoms at T1 and rumination at T2. These findings suggest that EF deficits play an active role in depression onset, maintenance, and/or recurrence.

A longitudinal study on the relationship between duration of untreated psychosis and executive function in early-onset first-episode psychosis

BackgroundThe relationship between duration of untreated psychosis (DUP) and executive function (EF) in patients with first-episode psychosis (FEP) is controversial. We aim to assess the influence of DUP on changes in EF over a 2-year period in subjects with early-onset FEP (first psychotic symptom before age 18) and less than 6months of positive symptoms. MethodsA total of 66 subjects were included in the study (19 females [28.8%], mean age 16.2±1.6years). The influence of DUP on changes in EF over the 2-year follow-up (expressed as a composite score of 5 cognitive abilities: attention, working memory, cognitive flexibility, response inhibition, and problem solving) was estimated using a multivariate linear regression model after removing the effect of intelligence quotient and controlling for age, gender, diagnosis, premorbid adjustment, severity of positive and negative symptoms at baseline, global functioning at baseline, and mean daily antipsychotic dosage during follow-up. ResultsMean DUP was 65.0±6.9days (95% confidence interval [CI], 51.2, 78.8). Median DUP was 47.5days (range 2–180days). Negative symptoms at baseline was the only variable significantly associated with EF at baseline (10.9% of explained variance [e.v. 10.9%], p=0.007). Only shorter DUP (e.v. 8.7%, p=0.013) and greater severity of baseline negative symptoms (e.v. 10.0%, p=0.008) were significantly associated with greater improvement in EF. ConclusionsIn early-onset FEP, shorter DUP was associated with greater improvement in EF over a 2-year follow-up period.

The emergent executive: a dynamic field theory of the development of executive function.

Executive function (EF) is a central aspect of cognition that undergoes significant changes in early childhood. Changes in EF in early childhood are robustly predictive of academic achievement and general quality of life measures later in adulthood. We present a dynamic neural field (DNF) model that provides a process-based account of behavior and developmental change in a key task used to probe the early development of executive function—the Dimensional Change Card Sort (DCCS) task. In the DCCS, children must flexibly switch from sorting cards either by shape or color to sorting by the other dimension. Typically, 3-year-olds, but not 5-year-olds, lack the flexibility to do so and perseverate on the first set of rules when instructed to switch. Using the DNF model, we demonstrate how rule-use and behavioral flexibility come about through a form of dimensional attention. Further, developmental change is captured by increasing the robustness and precision of dimensional attention. Note that although this enables the model to effectively switch tasks, the dimensional attention system does not “know” the details of task-specific performance. Rather, correct performance emerges as a property of system–wide interactions. We show how this captures children’s behavior in quantitative detail across 14 versions of the DCCS task. Moreover, we successfully test a set of novel predictions with 3-year-old children from a version of the task not explained by other theories.

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Background and aims: When parents are asked to describe their long-term concerns for their child with TBI, they often target executive dysfunction. Executive functions (EFs) are those cognitive abilities that regulate, control, and manage other cognitive processes. The mechanism of TBI-related EF changes is not well understood. Aims: We assessed the pattern of EF changes over the first year post-injury, including what EFs are affected, whether and how they recover, and potential predictors of these changes. Methods: 53 youth, age 5 to 18 years, who had sustained complicated mild to severe TBIs were recruited from five children’s hospitals in Canada (Institutional Review Boards provided approval of the study). Parents completed rating of EF symptoms (Behaviour Rating Inventory of Executive Function) at time of injury (baseline) and at 3, 6, and 12 months post-injury. Serum protein and brain neuroimaging analysis provided potential biomarkers of TBI-related EF changes. Results: Parent reports of EF changes are heterogeneous following pediatric TBI with some abilities reportedly minimally affected (inhibition, planning, organization), while others exhibit decline in the first 3 months (working memory and initiation) or 6 months (emotional control, flexibility, and monitoring behaviour). Many EFs fail to fully recover one year following injury. Serum and brain biomarkers may predict persisting changes in EF. Conclusions: An acute brain MRI and serum biomarkers of brain injury may be important prognostic tools for predicting the course of EF changes following TBI, which is important for patients and their families because EFs are known to affect cognitive processes (memory and attention), academic achievement, and behaviour regulation.

Executive Functions and Academic Achievement: Current Research and Future Directions

Executive Functions and Academic Achievement: Current Research and Future Directions