Neuroelectric and behavioral indices of interference control during acute cycling.

OBJECTIVE: This study examined the effects of in-task, moderate-intensity aerobic exercise on neuroelectric and behavioral indices of interference control, one component of executive control. METHODS: Forty-one participants completed a V O(2) max test to determine maximal heart rate (HR). On a separate day, event-related brain potentials and task performance were measured during the counterbalanced conditions of upright cycling at 60% of maximal HR and rest while performing congruent and incongruent trials of a flanker task. RESULTS: Exercise resulted in reduced response accuracy for incongruent trials relative to rest; an effect not found for congruent trials. Decreased N1 amplitude was observed during exercise at parietal sites and globally for N2. Exercise also resulted in increased amplitude for the P2 at frontal and central sites, and for the P3 at frontal and lateral sites. Further, longer N2 and P3 latencies were observed during exercise relative to rest. CONCLUSION: These findings suggest that the need to allocate attentional resources toward the large-scale bodily movements inherent in exercise may relate to inefficiency of neural resource allocation, resulting in decreased interference control. SIGNIFICANCE: These data indicate general and selective exercise-induced decrements in cognitive processing while performing acute aerobic exercise.     

Executive dysfunction and the course of geriatric depression.

BACKGROUND: Executive dysfunction is common in geriatric depression and persists after improvement of depressive symptoms. This study examined the relationship of executive impairment to the course of depressive symptoms among elderly patients with major depression. METHODS: A total of 112 nondemented elderly patients with major depression participated in an 8-week citalopram trial at a target daily dose of 40 mg. Executive functions were assessed with the initiation/perseveration subscale of the Dementia Rating Scale and the Stroop Color-Word test. Medical burden was rated with the Cumulative Illness Rating Scale. RESULTS: Both abnormal initiation/perseveration and abnormal Stroop Color-Word scores were associated with an unfavorable response of geriatric depression to citalopram. In particular, initiation/perseveration scores below the median (< or =35) and Stroop scores at the lowest quartile (< or =22) predicted limited change in depressive symptoms. Impairment in other Dementia Rating Scale cognitive domains did not significantly influence the outcome of depression. CONCLUSIONS: Executive dysfunction increases the risk for poor response of geriatric depression to citalopram. Because executive functions require frontostriatal-limbic integrity, this observation provides the rationale for investigation of the role of specific frontostriatal-limbic pathways in perpetuating geriatric depression. Depressed elderly patients with executive dysfunction require vigilant clinical attention because they might be at risk to fail treatment with a selective serotonin reuptake inhibiting antidepressant.     

Exercise,Fitness, and Neurocognitive Function in Older Adults: The “Selective Improvement” and “Cardiovascular Fitness” Hypotheses

Background   Although basic research has uncovered biological mechanisms by which exercise could maintain and enhance adult brain health, experimental human studies with older adults have produced equivocal results. Purpose   This randomized clinical trial aimed to investigate the hypotheses that (a) the effects of exercise training on the performance of neurocognitive tasks in older adults is selective, influencing mainly tasks with a substantial executive control component and (b) performance in neurocognitive tasks is related to cardiorespiratory fitness. Methods   Fifty-seven older adults (65–79 years) participated in aerobic or strength-and-flexibility exercise training for 10 months. Neurocognitive tasks were selected to reflect a range from little (e.g., simple reaction time) to substantial (i.e., Stroop Word–Color conflict) executive control. Results   Performance in tasks requiring little executive control was unaffected by participating in aerobic exercise. Improvements in Stroop Word–Color task performance were found only for the aerobic exercise group. Changes in aerobic fitness were unrelated to changes in neurocognitive function. Conclusions   Aerobic exercise in older adults can have a beneficial effect on the performance of speeded tasks that rely heavily on executive control. Improvements in aerobic fitness do not appear to be a prerequisite for this beneficial effect.

A meta-analysis of executive dysfunctions in unipolar major depressive disorder without psychotic symptoms and their changes during antidepressant treatment

Wagner S, Doering B, Helmreich I, Lieb K, Tadi? A. A meta‐analysis of executive dysfunctions in unipolar major depressive disorder without psychotic symptoms and their changes during antidepressant treatment. Objective: Empirical evidence supports the existence of significant executive deficits in patients with major depressive disorder (MDD) as compared to non‐depressed controls. Nevertheless, the effect size of executive dysfunctions in unipolar, non‐psychotic MDD as well as their relationship to antidepressant treatment is ambiguous. Method: Meta‐analytic methods were used to assess the severity of executive dysfunctions in unipolar, non‐psychotic MDD as compared to healthy controls and to investigate their course during antidepressant treatment. Results: Fifteen studies comparing the executive functions of 375 patients with DSM‐IV MDD and 481 healthy controls were analysed. Furthermore, in three studies, including 122 patients with MDD, the Stroop test performance was examined before and after antidepressant treatment. Patients with MDD performed 0.439 up to 1.18 (P < 0.0001) standard mean differences worse than healthy controls. The Stroop performance improved during the course of treatment (P = 0.0001). Conclusion: We revealed significant executive dysfunctions in patients with unipolar, non‐psychotic MDD compared with healthy controls and an improvement of the Stroop performance during the course of treatment. Future studies with different test procedures are needed to further investigate the influence of antidepressant treatment on executive functions.     

Heterogeneity in executive impairment in patients with very mild Alzheimer's disease

BACKGROUND/AIMS: The presence of executive impairment in mild Alzheimer's disease (AD) has primarily been demonstrated by means of group comparison. Whether executive dysfunction is a common feature of mild AD or only present in a subgroup of patients remains unclear. The aim of this study was to describe the frequency of impairment on a set of internationally well-known executive tests in patients with very mild AD. METHODS: Thirty-six patients with very mild AD (MMSE scores above 23) and 32 healthy control subjects were administered a battery of 7 executive tests: Trail Making part B, Stroop Interference Test, modified Wisconsin Card Sorting Test (WCST), category- and letter-based verbal fluency, a design fluency task and the Similarities subtest from WAIS. Impairment was defined as a score of 2 SD or more below control means. RESULTS: Executive impairment on at least 1 measure was seen in 76% of the patients, and 50% were impaired on 2 or more tests. Trail Making B and Stroop Interference Test were impaired in more than 40%, whereas only few patients were impaired on Similarities, WCST and design fluency. A wide variation of executive test profiles was seen among the patients. CONCLUSION: Executive impairments are common in early AD and not just a feature characteristic of a subgroup of patients. Complex attentional skills are more frequently affected than other executive functions. There is, however, considerable heterogeneity among AD patients in the pattern of executive dysfunction.     

An event-related potential investigation of the acute effects of aerobic and coordinative exercise on inhibitory control in children with ADHD

The current body of evidence suggests that an aerobic exercise session has a beneficial effect on inhibitory control, whereas the impact of coordinative exercise on this executive function has not yet been examined in children with ADHD. Therefore, the present study aims to investigate the acute effects of aerobic and coordinative exercise on behavioral performance and the allocation of attentional resources in an inhibitory control task.Using a cross-over design, children with ADHD-combined type and healthy comparisons completed a Flanker task before and after 20 min moderately-intense cycling exercise, coordinative exercise and an inactive control condition. During the task, stimulus-locked event-related potentials were recorded with electroencephalography.Both groups showed an increase of P300 amplitude and decrease of reaction time after exercise compared to the control condition. Investigating the effect of exercise modality, aerobic exercise led to greater increases of P300 amplitude and reductions in reaction time than coordinative exercise in children with ADHD.The findings suggest that a single exercise bout improves inhibitory control and the allocation of attentional resources. There were some indications that an aerobic exercise session seems to be more efficient than coordinative exercise in reducing the inhibitory control deficits that persist in children with ADHD.     

Impaired response inhibition in veterans with post-traumatic stress disorder and mild traumatic brain injury

Combat veterans with post-traumatic stress disorder (PTSD) can show impairments in executive control and increases in impulsivity. The current study examined the effects of PTSD on motor response inhibition, a key cognitive control function. A Go/NoGo task was administered to veterans with a diagnosis of PTSD based on semi-structured clinical interview using DSM-IV criteria (n = 40) and age-matched control veterans (n = 33). Participants also completed questionnaires to assess self-reported levels of PTSD and depressive symptoms. Performance measures from the patients (error rates and reaction times) were compared to those from controls. PTSD patients showed a significant deficit in response inhibition, committing more errors on NoGo trials than controls. Higher levels of PTSD and depressive symptoms were associated with higher error rates. Of the three symptom clusters, re-experiencing was the strongest predictor of performance. Because the co-morbidity of mild traumatic brain injury (mTBI) and PTSD was high in this population, secondary analyses compared veterans with PTSD+mTBI (n = 30) to veterans with PTSD only (n = 10). Although preliminary, results indicated the two patient groups did not differ on any measure (p > .88). Since cognitive impairments could hinder the effectiveness of standard PTSD therapies, incorporating treatments that strengthen executive functions might be considered in the future. (JINS, 2012, 18, 1-10).     

Executive control of attention in individuals with contamination‐related obsessive–compulsive symptoms

Background: In this study, we examined executive control of attention in individuals with contamination‐related obsessive–compulsive (OC) symptoms using a modified version of the Eriksen flanker task. The task indexes one's ability to resolve attentional conflict between different responses and to ignore task distracters. Methods: For this study, we modified the original flanker task using affective words to examine the effect of threat‐relevant stimuli on executive control of attention. Consistent with research on information processing biases in individuals with OC symptoms, we hypothesized that the flanker interference effect (i.e., difference in response latencies between incongruent and congruent flanker trials) will be greater for threat‐related flankers in individuals with OC symptoms (n=32), relative to a control group (n=36). Results: Results of our study were consistent with our hypothesis: The interference effect for threat flankers was greater in individuals with OC symptoms than in those low in symptoms. Moreover, there was no differential interference effect in the low and high symptom groups for neutral flankers. Conclusions: These findings suggest that the presence of threat‐relevant distracters disrupts executive control of attention in individuals with contamination‐related OC symptoms. These results are consistent with extant research on attentional biases in individuals with clinical and subclinical symptoms of OCD. Depression and Anxiety, 2010. © 2010 Wiley‐Liss, Inc.     

Aerobic exercise increases hippocampal volume and improves memory in multiple sclerosis: Preliminary findings

Multiple sclerosis leads to prominent hippocampal atrophy, which is linked to memory deficits. Indeed, 50% of multiple sclerosis patients suffer memory impairment, with negative consequences for quality of life. There are currently no effective memory treatments for multiple sclerosis either pharmacological or behavioral. Aerobic exercise improves memory and promotes hippocampal neurogenesis in nonhuman animals. Here, we investigate the benefits of aerobic exercise in memory-impaired multiple sclerosis patients. Pilot data were collected from two ambulatory, memory-impaired multiple sclerosis participants randomized to non-aerobic (stretching) and aerobic (stationary cycling) conditions. The following baseline/follow-up measurements were taken: high-resolution MRI (neuroanatomical volumes), fMRI (functional connectivity), and memory assessment. Intervention was 30-minute sessions 3 times per week for 3 months. Aerobic exercise resulted in 16.5% increase in hippocampal volume and 53.7% increase in memory, as well as increased hippocampal resting-state functional connectivity. Improvements were specific, with no comparable changes in overall cerebral gray matter (+2.4%), non-hippocampal deep gray matter structures (thalamus, caudate: ?4.0%), or in non-memory cognitive functioning (executive functions, processing speed, working memory: changes ranged from ?11% to +4%). Non-aerobic exercise resulted in relatively no change in hippocampal volume (2.8%) or memory (0.0%), and no changes in hippocampal functional connectivity. This is the first evidence for aerobic exercise to increase hippocampal volume and connectivity and improve memory in multiple sclerosis. Aerobic exercise represents a cost-effective, widely available, natural, and self-administered treatment with no adverse side effects that may be the first effective memory treatment for multiple sclerosis patients.     

Acute exercise facilitates brain function and cognition in children who need it most: An ERP study of individual differences in inhibitory control capacity

The present study examined the effects of moderate-intensity aerobic exercise on aspects of cognitive control in two groups of children categorized by higher- and lower-task performance. Event-related brain potentials (ERPs) were collected in 40 preadolescent children during a modified flanker task following 20 min of treadmill walking and seated rest on separate occasions. Participants were bifurcated into two groups based on task performance following the resting session. Findings revealed that following exercise, higher-performers maintained accuracy and exhibited no change in P3 amplitude compared to seated rest. Lower-performers demonstrated a differential effect, such that accuracy measures improved, and P3 amplitude increased following exercise. Lastly, both groups displayed smaller N2 amplitude and shorter P3 latency following exercise, suggesting an overall facilitation in response conflict and the speed of stimulus classification. The current findings replicate prior research reporting the beneficial influence of acute aerobic exercise on cognitive performance in children. However, children with lower inhibitory control capacity may benefit the most from single bouts of exercise. These data are among the first to demonstrate the differential effect of physical activity on individuals who vary in inhibitory control, and further support the role of aerobic exercise for brain health during development.     

Executive control deficits correlate with reduced frontal white matter volume in multiple sclerosis

Introduction: Executive control deficits are frequently reported in patients with multiple sclerosis (MS). We have previously proposed that in the context of competing automatic and volitional processes, such deficits may in part reflect poor resolution of response conflict. This study aimed to investigate the neuropathological underpinnings of executive control deficits in MS, focusing on the frontostriatal system proposed to mediate executive control.

Method: Forty-one MS patients and 25 healthy controls completed measures of executive control that have previously been used to characterize deficit in MS: antisaccade and endogenously cued saccade paradigms, and the Stroop color and word test. Relationships between task performance and volumetric measures of frontal white matter, frontal gray matter, striatum, and pallidum were investigated.

Results: MS participants performed significantly more poorly on the Stroop and antisaccade tasks than controls. For MS patients, higher erroneous responding on the antisaccade task was related to reduced frontal white matter volume.

Conclusion: These findings suggest that loss of frontal white matter may underlie executive control deficits in MS, and provides information that may inform the development of targeted cognitive training strategies in MS.     

早期帕金森病的模糊决策功能障碍

目的探讨早期帕金森病(Parkinson’s disease,PD)患者在概率不明确条件下的模糊决策能力是否受损,并分析该功能损害与其他认知功能的关系以及是否与基底节区病变有关。方法研究对象为年龄、性别匹配的早期PD患者(Hoehn-Yahr分级≤Ⅱ级)、右侧基底节梗死(right basal ganglia infarction,BGI)患者和正常对照各20名。采用蒙特利尔认知评估量表、Stroop字色测试等工具对进行背景认知功能测试,采用爱荷华博弈实验(Iowa Gambling Task,IGT)对各组进行模糊决策评测,分析IGT测试成绩与背景认知之间的相关性。结果3组Stroop测试成绩的差异有统计学意义(F=33.27,P<0.05),PD组(21.35±4.28)差于BGI组(13.30±3.21)和对照组(13.60±2.98)(P<0.05)。3组在IGT测试成绩差异亦有统计学意义(F=5.38,P<0.05),PD组总有利备择得分(48.95±7.01)低于BGI组(52.95±2.72)和正常对照组(53.15±2.43)(P<0.05)。BGI组的Stroop测试和模糊决策IGT测试成绩与对照组比较,差异均无统计学意义(P>0.05)。早期PD患者IGT测试成绩与Stroop测试成绩呈负相关(r=-0.65,P<0.05)。结论早期PD患者存在模糊决策障碍和执行功能障碍,两者间存在相关性。单纯基底节区脑梗死对模糊决策和执行功能无显著影响。PD患者模糊决策障碍可能源于基底节以外脑区损害。     

Lower cognitive performance in healthy G2019S LRRK2 mutation carriers

OBJECTIVE: To assess cognitive abilities of healthy first-degree relatives of Ashkenazi patients with Parkinson disease (PD), carriers of the G2019S mutation in the LRRK2 gene. METHODS: In this observational study, 60 consecutive healthy first-degree relatives (aged 50.9 ± 6.2 years; 48% male; 30 G2019S carriers) were assessed using a computerized cognitive program, the Montreal Cognitive Assessment questionnaire, the Unified Parkinson's Disease Rating Scale Part III, and the Geriatric Depression Scale. RESULTS: G2019S carriers scored significantly lower on the computerized executive function index (p = 0.04) and on specific executive function tasks (Stroop test, p = 0.007). CONCLUSION: Carrying the LRRK2 G2019S mutation was associated with lower executive performance in a population at risk for PD.     

Executive control deficit in depression: event-related potentials in a Go/Nogo task

Growing evidence suggests an impairment of executive control functions in depression. The aim of this study was to investigate whether depressive patients show a specific impairment of executive control in a response inhibition task and to investigate its neurophysiological correlates using event-related potentials. We analyzed data from 16 patients with unipolar depression and 16 healthy controls using an auditory Go/Nogo task. High resolution event-related potentials (ERPs) were recorded. Depressive patients performed similar to controls in the Go task, but worse in the Nogo task, which required response inhibition. ERPs revealed the neurophysiological correlate of this deficit. Both groups showed the same voltage pattern in the Go task. However, in the Nogo task depressive patients showed a reduction of an early fronto-temporal positivity in the N2 time window, which was associated with response inhibition in healthy subjects. This effect could not be explained by increased task difficulty in the Nogo task. There was no difference between groups in later stages of processing as indexed by the P3 complex. Therefore, the findings suggest a specific deficit in response inhibition, which requires executive control. This deficit is thought to reflect dysfunctional activation of the network subserving executive control during an early stage of cortical processing.     

Familial clustering of executive functioning in affected sibling pair families with ADHD

OBJECTIVE: To investigate familial clustering of executive functioning (i.e., response inhibition, fine visuomotor functioning, and attentional control) in attention-deficit/hyperactivity disorder (ADHD)-affected sibling pairs. METHOD: Fifty-two affected sibling pairs aged 6 to 18 years and diagnosed with ADHD according to DSM-IV performed the Stroop test, go/no-go task, two different fine visuomotor tracking tasks, and a sustained-, divided-, and focused attention task. RESULTS: Significant correlations (r = 0.4) were found between siblings for response inhibition and attentional control and for fine visuomotor skills that made high demands on executive functioning. CONCLUSIONS: Response inhibition, higher order controlled fine visuomotor functioning, and attentional control seem to cluster in ADHD-affected siblings. This suggests that these aspects of executive dysfunctioning may reflect an endophenotype of ADHD. Measurement of these executive functions may facilitate the identification of genes involved in ADHD by forming more homogeneous subgroups.     

Executive Functions in Patients with Familial versus Sporadic Schizophrenia and Their Parents

Background: The aim of this study was to investigate the executive functions in patients with sporadic schizophrenia (SS) and familial schizophrenia (FS), and the executive functions in their parents. Methods: The study included 30 patients with FS and their 37 parents with a positive family history of schizophrenia; 30 patients with SS and their 44 parents; 30 controls matched with the patients for gender, age and education, and 40 controls matched with the parents for gender, age and education (211 subjects in total). All the subjects were interviewed with the Structured Clinical Interview for DSM-IV-Axis I (SCID-I). The executive functions were assessed using the Verbal Fluency Test (VFT), the Trail Making Test (TMT), the Wisconsin Card Sorting Test (WCST) and the Stroop Test. Results: Patients with FS and their parents, and patients with SS performed significantly worse than their controls on the VFT, TMT, WCST and the Stroop test. There were no statistically significant differences between parents of patients with SS and their controls on any of the tests except for the Stroop color score. FS parents performed significantly worse than SS parents on all tests. FS patients performed significantly worse than SS patients on the VFT, TMT, Stroop test. Conclusion: Previous studies that investigated the cognitive functions of relatives of patients with schizophrenia brought out inconsistent results. The present study investigated relatives with and without a family history of schizophrenia separately and found that executive functions were impaired only in parents with a positive family history of schizophrenia. These findings suggest that impairment in executive functions may represent a genetic endophenotype for schizophrenia.     

Neuropsychological executive functions and DSM-IV ADHD subtypes.

OBJECTIVE: To evaluate and compare a focused set of component neuropsychological executive functions in the DSM-IV attention-deficit/hyperactivity disorder combined (ADHD-C) and inattentive (ADHD-I) subtypes. METHOD: The Stop task, Tower of London, Stroop task, Trailmaking Test, and output speed measures were completed by 105 boys and girls aged 7-12 classified as either DSM-IV ADHD-C (n = 46), ADHD-I (n = 18), or community control (n = 41). RESULTS: Both subtypes had deficits on output speed. A group x gender interaction was observed on the Stop task: boys with ADHD-C were impaired versus boys with ADHD-I, whereas girls in the two subtypes did not differ. The ADHD-C type had a deficit in planning. Neither ADHD group had a deficit in interference control per se, although they were slower than controls on the Stroop tasks. CONCLUSIONS: ADHD-I shares neuropsychological deficits with ADHD-C in the domain of output speed; on most domains the subtypes did not differ. Neuropsychological distinctions between these ADHD subtypes may be few, depending on which domain of executive functioning is assessed, and these distinctions differ by gender. In the case of boys, the two subtypes may be distinguished by the specificity of motor inhibition deficits to ADHD-C.     

Time-based prospective memory in severe traumatic brain injury patients: the involvement of executive functions and time perception

Prospective memory (PM) is the ability to remember to perform a future action at a specified later time, which is investigated through the use of event-based and time-based tasks. Prior investigations have found that PM is impaired following traumatic brain injury (TBI). However, there is limited information regarding the cognitive functions that mediate TBI and PM performance. Thus, this study investigated time-based PM in TBI patients, and the relationship among time-based PM, time perception, and executive functions. To accomplish this objective, 18 severe TBI patients and 18 healthy matched controls performed a time-based PM task, a time reproduction task, and two executive functions (Stroop and n-back) tasks. While both groups increased their monitoring frequency close to the target time, TBI patients monitored more and were less accurate than healthy controls at the target time confirming the time-based PM dysfunction in these patients. Importantly, executive functions, particularly inhibition and updating abilities, were strongly related to time-based PM performance; both time perception and executive functions are involved in time-based prospective memory in controls, whereas, only executive functions appear to be involved in TBI time-based prospective memory performance.     

The random number generation task: psychometric properties and normative data of an executive function task in a mixed sample.

We investigated the psychometric properties of the random number generation (RNG) task in four studies using a mixed sample of young adults (n = 306), middle-aged adults (n = 40), and patients diagnosed with schizophrenia (n = 26). Data in study 1 were best accounted for by a three-factor solution representing inhibition of stereotypical schemas (seriation), output inhibition (repetition), and monitoring of previous output (cycling). Modest test-retest correlations were found, with the seriation factor showing acceptable stability across time (study 2). In study 3, RNG task performance was related to scores on concurrent neurocognitive tasks to establish construct validity. RNG scores correlated with healthy controls' performance on the Stroop color-word test and patients diagnosed with schizophrenia with executive dysfunctions. Patients diagnosed with schizophrenia performed poorer on the seriation factor of the RNG than healthy control participants (study 4). Our results indicate that the RNG task has modest to acceptable psychometric properties. It primarily taps executive subfunctions (i.e., inhibition, updating, and monitoring), which are affected by psychopathological or neurological deficits.     

Stroop performance in bipolar disorder: further evidence for abnormalities in the ventral prefrontal cortex

OBJECTIVES: Bipolar patients are impaired in Stroop task performance, a measure of selective attention. Structural and functional abnormalities in task-associated regions, in particular the prefrontal cortex (PFC), have been reported in this population. We aimed to examine the relationship between functional abnormalities, impaired task performance and the severity of depressive symptoms in bipolar patients. METHODS: Remitted bipolar patients (n = 10; all medicated), either euthymic or with subsyndromal depression, and age-matched control subjects (n = 11) viewed 10 alternating blocks of incongruent Stroop and control stimuli, naming the colour of the ink. Neural response was measured using functional magnetic resonance imaging. We computed between-group differences in neural response and within-group correlations with mood and anxiety. RESULTS: There were no significant between-group differences in task performance. During the Stroop condition, controls demonstrated greater activation of visual and dorsolateral and ventrolateral prefrontal cortical areas; bipolar patients demonstrated relative deactivation within orbital and medial prefrontal cortices. Depression scores showed a trend towards a negative correlation with the magnitude of orbitofrontal cortex deactivation in bipolar patients, whereas state anxiety correlated positively with activation of dorsolateral PFC and precuneus in controls. CONCLUSIONS: Our findings confirm previous reports of decreased ventral prefrontal activity during Stroop task performance in bipolar patients, and suggest a possible negative correlation between this and depression severity in bipolar patients. These findings further highlight the ventromedial PFC as a potential candidate for illness related dysfunction in bipolar disorder.