Attention Network Test in adults with ADHD--the impact of affective fluctuations

Altered hemispheric asymmetry of attentional networks in patients with pituitary adenoma: an event-related potential study

Background

Emerging evidence has been reported of attentional dysfunction in pituitary adenoma patients. However, the effect of pituitary adenomas on lateralized attention network efficiency remained to be clear. Thus, the present study aimed to investigate the impairment of lateralized attention networks in patients with pituitary adenoma.

Methods

Eighteen pituitary adenoma patients (PA group) and 20 healthy controls (HCs) were included in this study. Both behavioral results and event-related potentials (ERPs) were acquired while subjects performed the Lateralized Attention Network Test (LANT).

Results

Behavioral performances indicated the PA group had a slower reaction time and a similar error rate relative to the HCs group. Meanwhile, significantly increased executive control network efficiency suggested the dysfunction of inhibition control in PA patients. Regarding ERP results, there were no group differences in the alerting and orienting networks. The target-related P3 was significantly reduced in the PA group, suggesting an impairment of executive control function and attentional resources allocation. Moreover, the mean amplitude of P3 was significantly lateralized to the right hemisphere, and interacted with the visual field, exhibiting that the right hemisphere dominated the bilateral visual field, whereas the left hemisphere dominated the left visual field. In the specific high-conflict condition, the pattern of hemispheric asymmetry in the PA group was altered due to a mixed effect resulting from the compensatory recruitment of attentional resources in the left central parietal area and the destructive effects of hyperprolactinemia.

Conclusion

These findings suggested that, in the lateralized condition, the decreased P3 in the right central parietal area and the diminished hemispheric asymmetry under high conflict load, may serve as the potential biomarkers of attentional dysfunction in patients with pituitary adenoma.

A self-guided internet-delivered intervention for adults with ADHD: Results from a randomized controlled trial

Background

Attention-deficit/hyperactivity disorder (ADHD) in adulthood, with an estimated prevalence of 2–3 %, is associated with several challenges in daily life functioning. Still, the availability of evidence-based psychological interventions for adults with ADHD is limited. Interventions delivered over the Internet on smartphones or personal computers may help to increase the availability of and access to effective psychological interventions.

Objective

This study reports on the efficacy of a self-guided psychological Internet-delivered intervention on severity levels of ADHD symptomatology and quality of life in adults with ADHD.

Methods

Adults with a self-reported ADHD diagnosis (N = 120) were included in a randomized controlled trial with two arms: 1) self-guided Internet-delivered intervention for managing symptoms and impairments related to ADHD (n = 61); 2) online psychoeducation module (control group, n = 59). The primary clinical outcome was severity levels of ADHD as measured with the Adult ADHD Self-Report Scale. Secondary outcomes were quality of life as measured with the Adult ADHD Quality of Life scale and stress as measured with the Perceived Stress Scale. Measures were obtained at three time points: before (baseline), immediately after (8 weeks) and 3 months after the intervention. The secondary objective of the study was to explore user satisfaction with and adherence to the intervention.

Results

Linear Mixed Model analysis revealed moderate to large between group effect-size improvements on self-report measures of ADHD symptomatology (d = 0.70) and quality of life (d = 0.53). Importantly, effects were maintained at 3-month follow-up (d = 0.76 and d = 0.52). In terms of adherence, 29 % completed all modules, while 59 % completed at least five modules (out of 7). Treatment satisfaction was adequate, with n = 34 (79 %) indicating that they were very satisfied or satisfied with the intervention, and n = 37 (88 %) indicating that they would recommend the intervention to a friend.

Discussion

The study demonstrated the efficacy of a self-guided Internet-delivered intervention by showing reliable and statistically significant improvements in self-reported ADHD symptomatology and quality of life. The intervention may be suitable for better managing ADHD symptoms in primary care and as a low intensity intervention population wide.

Trial registration

ClinicalTrials.gov, Identifier NCT04726813, January 27, 2021.

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The intervention significantly reduced ADHD symptoms and increased quality of life.

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Between group effect sizes were moderate to large on the primary outcome.

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Within group effect sizes were large for the intervention group.

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Fifty-eight percent of intervention group participants demonstrated reliable change.

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The majority of the participants were satisfied with the intervention.

Stability of Attention Performance of Adults with ADHD over Time: Evidence from Repeated Neuropsychological Assessments in One-Month Intervals

Neuropsychological assessments of attention are valuable sources of information in the clinical evaluation of adults with attention-deficit/hyperactivity disorder (ADHD). However, it is unclear whether the attention performance of adults with ADHD is stable or fluctuates over time, which is of great importance in the interpretation of clinical assessments. This study aimed to explore the stability of attention performance of adults with ADHD in repeated assessments at one-month intervals. Twenty-one adults diagnosed with ADHD took part in this study by completing selective attention and vigilance tests three times, each one month apart. Test scores of participants were compared with and interpreted based on test norms. A considerable proportion of 'below average' performance scores were observed in most of the variables of selective attention and vigilance in all three assessments. Further, selective attention and vigilance performance scores did not differ significantly between the three repeated assessments. Finally, the majority of participants received consistent test score interpretations across the three repeated assessments. This study confirms previous research and highlights abnormal selective attention and vigilance performance in adults with ADHD. Further, this study preliminarily demonstrates relatively stable attention performance across repeated assessments, which has the potential to support clinical assessment, treatment planning, and evaluation.

Goal management training improves executive control in adults with ADHD: an open trial employing attention network theory to examine effects on attention

Background

Adults with Attention-Deficit/Hyperactivity Disorder (ADHD) typically experience poorer attentional control. According to the attention network theory, attentional control relies on three interacting networks of alerting, orienting, and executive control. In ADHD, it is mainly the alerting and executive control networks that are suggested and found to be compromised.

Methods

In the current study, we investigated if a group-based metacognitive remediation program (Goal Management Training [GMT]) in adults with ADHD would enhance attentional control using an experimental measure of the attention network theory. We expected that GMT would specifically enhance the executive control and alerting networks.

Results

Data from post- and follow up-assessments of 21 adults (age: 39.05 [11.93]) with ADHD who had completed GMT were included. Linear mixed-effects modeling revealed significant improvements in the functioning of the executive control network for the majority of the participants, although a small subset of participants showed a negative development following the intervention. Results also showed an improvement in the orienting network at follow up, but no change in the alerting network.

Conclusion

The results may indicate that improvements in the functioning of the executive control network are central to the positive effects of GMT reported in disorders characterized by impaired attentional control.

Trial registration: The study was retrospectively registered in the ISRCTN (Identifier: ISRCTN91988877) on the 18/01/2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-022-00902-9.

Two sides of the same coin: ADHD affects reactive but not proactive inhibition in children

Children with attention-deficit/hyperactivity disorder (ADHD) present a deficit in inhibitory control. Still, it remains unclear whether it comes from a deficit in reactive inhibition (ability to stop the action in progress), proactive inhibition (ability to exert preparatory control), or both.We compared the performance of 39 children with ADHD and 42 typically developing children performing a Simon choice reaction time task. The Simon task is a conflict task that is well-adapted to dissociate proactive and reactive inhibition. Beyond classical global measures (mean reaction time, accuracy rate, and interference effect), we used more sophisticated dynamic analyses of the interference effect and accuracy rate to investigate reactive inhibition. We studied proactive inhibition through the congruency sequence effect (CSE).Our results showed that children with ADHD had impaired reactive but not proactive inhibition. Moreover, the deficit found in reactive inhibition seems to be due to both a stronger impulse capture and more difficulties in inhibiting impulsive responses. These findings contribute to a better understanding of how ADHD affects inhibitory control in children.

Attentional networks, vigilance, and distraction as a function of attention-deficit/hyperactivity disorder symptoms in an adult community sample

Attentional difficulties are a core axis in attention-deficit/hyperactivity disorder (ADHD). However, establishing a consistent and detailed pattern of these neurocognitive alterations has not been an easy endeavour. Based on a dimensional approach to ADHD, the present study aims at comprehensively characterizing three key attentional domains: the three attentional networks (alerting, orienting, and executive attention), two components of vigilance (executive and arousal vigilance), and distraction. To do so, we modified a single, fine-grained task (the ANTI-Vea) by adding irrelevant distractors. One hundred and twenty undergraduates completed three self-reports of ADHD symptoms in childhood and adulthood and performed the ANTI-Vea. Despite the low reliability of some ANTI-Vea indexes, the task worked successfully. While ADHD symptoms in childhood were related to alerting network and arousal vigilance, symptoms in adulthood were linked to executive vigilance. No association between ADHD symptom severity and executive attention and distraction was found. In general, our hypotheses about the relationships between ADHD symptoms and attentional processes were partially supported. We discuss our findings according to ADHD theories and attention measurement.

Assessing the Three Attentional Networks and Vigilance in the Adolescence Stages

Attention involves three functionally and neuroanatomically distinct neural networks: alerting, orienting, and executive control. This study aimed to assess the attentional networks and vigilance in adolescents aged between 10 and 19 years using the attentional network test for interaction and vigilance (ANTI-V). One hundred and eighty-two adolescents divided into three groups (early adolescents, middle adolescents, late adolescents) participated in the study. The results indicate that after age 15, adolescents adopt a more conservative response strategy and increase the monitoring of self-errors. All the attentional networks seem to continue to develop during the age range considered in this study (10–19 y). Performance improved from early adolescence to middle adolescence and began to stabilize in late adolescence. Moreover, a low level of vigilance seems to harm alerting and orienting abilities.

Cognitive characterization of adult attention deficit hyperactivity disorder by domains: a systematic review

Attention deficit hyperactivity disorder (ADHD) is reportedly the most frequent neurodevelopmental disorder diagnosed during childhood, and it is recognized as a common condition in adulthood. We review the evidence to help identify cognitive domains associated to deficits in adult ADHD. A systematic review with narrative synthesis was performed, assessing studies on adult ADHD, neuropsychology and research on involved cognitive domains in adults 18+ years old with an established diagnosis of ADHD, in seven electronic databases (PubMed, PsychInfo, WebOfScience, Embase, Scopus, OvidSPMedline, and Teseo), and Worldcat and OpenGrey grey literature databases. 93 studies were included for this review, encompassing findings from a total 5574 adults diagnosed only with ADHD, medication-naïve or non-medicated at the moment of the assessment and 4880 healthy controls. Adults diagnosed with ADHD may show, when compared to healthy controls, a cognitive profile characterized by deficits across all attention modalities, processing speed, executive function (mainly working memory and inhibition with emphasis on reward delay and interference control), verbal memory, reading skills, social cognition and arithmetic abilities. A cognitive characterization of adult ADHD by domains is established beyond the sole consideration of attention and executive function problems. Along with these, verbal memory, language (mainly reading), social cognition and arithmetic abilities may also contribute to a more comprehensive characterization of the cognitive profile in adult ADHD.

Normal executive attention but abnormal orienting attention in individuals with sluggish cognitive tempo

Background/objective: Sluggish Cognitive Tempo (SCT) is an attentional disorder characterized by the symptoms of slowness in behavior or thinking, a lack of en.ergy, difficulty initiating and sustaining effort, daydreaming, and drowsiness. The aim of the present study was to investigate the distinctive attentional characteristics of SCT as compared to Attention-Deficit/Hyperactivity Disorder (ADHD). Method: A total of 110 adults were recruited and divided into four groups: SCT+ADHD, SCT, ADHD, and healthy controls. The Revised version of Attention Networks Test was used to investigate each group’s attentional profile. Results: The results revealed that the two SCT groups (SCT+ADHD and SCT) showed a significantly weaker orienting network due to the problems of engaging and disengaging attention than the other two groups. Additionally, the two ADHD groups (SCT+ADHD and ADHD) showed a significantly weaker executive control network than the other two groups. Conclusions: The findings demonstrate an attentional distinction between the SCT and the ADHD groups with a greater dysfunction in the orienting network in the SCT group as compared to the ADHD group. Furthermore, a greater executive control dysfunction was observed in the ADHD group as compared to the SCT group.

A systematic review of transcranial direct current stimulation effects in attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) stands out as the most prevalent neurodevelopmental disorder of childhood, with global prevalence ranging from 3.4% to 7•2%. Its cognitive symptoms result from the combination of complex etiological processes encompassing genetic and environmental components. Available therapeutic approaches are associated with significant challenges such as modest efficacy or side effects. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in neuropsychiatric disorders. Trials investigating its applicability in ADHD have showed propitious, however, still preliminary findings.

METHODS

We performed a systemic review by searching on Medline, Cochrane Library, Web of Science, ScienceDirect and Embase using the descriptors: "attention-deficit/hyperactivity disorder" or "ADHD"; and "transcranial direct current stimulation" or "tDCS"; following PRISMA guidelines.

RESULTS

A total of 383 articles were identified. After removing duplicates, 45 studies were assessed for eligibility, and after careful review, 11 manuscripts applying tDCS in ADHD were included. Significant improvements in attention, inhibitory control and working memory were reported, in addition to increased brain connectivity following use of active tDCS.

LIMITATIONS

The main limitation was the small number of trials investigating use of tDCS in ADHD. Study methods and outcome measures were quite variable, and generally did not include long-term follow-up.

CONCLUSIONS

Although the extent literature indicates promising findings, the available data remains highly preliminary. Further trials evaluating the efficacy of tDCS for ADHD, with longer follow-up, are necessary. These studies will be needed to determine the optimal protocol for clinical efficacy.

Attention Networks in ADHD Adults after Working Memory Training with a Dual n-Back Task

Patients affected by Attention-Deficit/Hyperactivity Disorder (ADHD) are characterized by impaired executive functioning and/or attention deficits. Our study aim is to determine whether the outcomes measured by the Attention Network Task (ANT), i.e., the reaction times (RTs) to specific target and cue conditions and alerting, orienting, and conflict (or executive control) effects are affected by cognitive training with a Dual n-back task. We considered three groups of young adult participants: ADHD patients without medication (ADHD), ADHD with medication (MADHD), and age/education-matched controls. Working memory training consisted of a daily practice of 20 blocks of Dual n-back task (approximately 30 min per day) for 20 days within one month. Participants of each group were randomly assigned into two subgroups, the first one with an adaptive mode of difficulty (adaptive training), while the second was blocked at the level 1 during the whole training phase (1-back task, baseline training). Alerting and orienting effects were not modified by working memory training. The dimensional analysis showed that after baseline training, the lesser the severity of the hyperactive-impulsive symptoms, the larger the improvement of reaction times on trials with high executive control/conflict demand (i.e., what is called Conflict Effect), irrespective of the participants’ group. In the categorical analysis, we observed the improvement in such Conflict Effect after the adaptive training in adult ADHD patients irrespective of their medication, but not in controls. The ex-Gaussian analysis of RT and RT variability showed that the improvement in the Conflict Effect correlated with a decrease in the proportion of extreme slow responses. The Dual n-back task in the adaptive mode offers as a promising candidate for a cognitive remediation of adult ADHD patients without pharmaceutical medication.

Look duration at the face as a developmental endophenotype: elucidating pathways to autism and ADHD

Identifying developmental endophenotypes on the pathway between genetics and behavior is critical to uncovering the mechanisms underlying neurodevelopmental conditions. In this proof-of-principle study, we explored whether early disruptions in visual attention are a unique or shared candidate endophenotype of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). We calculated the duration of the longest look (i.e., peak look) to faces in an array-based eye-tracking task for 335 14-month-old infants with and without first-degree relatives with ASD and/or ADHD. We leveraged parent-report and genotype data available for a proportion of these infants to evaluate the relation of looking behavior to familial (n = 285) and genetic liability (using polygenic scores, n = 185) as well as ASD and ADHD-relevant temperament traits at 2 years of age (shyness and inhibitory control, respectively, n = 272) and ASD and ADHD clinical traits at 6 years of age (n = 94).

Results showed that longer peak looks at the face were associated with elevated polygenic scores for ADHD (β = 0.078, p = .023), but not ASD (β = 0.002, p = .944), and with elevated ADHD traits in mid-childhood (F(1,88) = 6.401, p = .013, $\eta _p^2$=0.068; ASD: F (1,88) = 3.218, p = .076), but not in toddlerhood (ps > 0.2). This pattern of results did not emerge when considering mean peak look duration across face and nonface stimuli. Thus, alterations in attention to faces during spontaneous visual exploration may be more consistent with a developmental endophenotype of ADHD than ASD. Our work shows that dissecting paths to neurodevelopmental conditions requires longitudinal data incorporating polygenic contribution, early neurocognitive function, and clinical phenotypic variation.

Attentional Processes in Children With Attentional Problems or Reading Difficulties as Revealed Using Brain Event-Related Potentials and Their Source Localization

Visual attention-related processes include three functional sub-processes: alerting, orienting, and inhibition. We examined these sub-processes using reaction times, event-related potentials (ERPs), and their neuronal source activations during the Attention Network Test (ANT) in control children, attentional problems (AP) children, and reading difficulties (RD) children. During the ANT, electroencephalography was measured using 128 electrodes on three groups of Finnish sixth-graders aged 12–13 years (control = 77; AP = 15; RD = 23). Participants were asked to detect the direction of a middle target fish within a group of five fish. The target stimulus was either preceded by a cue (center, double, or spatial), or without a cue, to manipulate the alerting and orienting sub-processes of attention. The direction of the target fish was either congruent or incongruent in relation to the flanker fish, thereby manipulating the inhibition sub-processes of attention. Reaction time performance showed no differences between groups in alerting, orienting, and inhibition effects. The group differences in ERPs were only found at the source level. Neuronal source analysis in the AP children revealed a larger alerting effect (double-cued vs. non-cued target stimuli) than control and RD children in the left occipital lobe. Control children showed a smaller orienting effect (spatially cued vs. center-cued target stimuli) in the left occipital lobe than AP and RD children. No group differences were found for the neuronal sources related to the inhibition effect. The neuronal activity differences related to sub-processes of attention in the AP and RD groups suggest different underlying mechanisms for attentional and reading problems.

Insomnia, Alcohol Consumption and ADHD Symptoms in Adults

Introduction

Substance use disorders and insomnia are common in the general population, and particularly among adults with attention-deficit/hyperactivity disorder (ADHD). Here we investigated the relationship between insomnia, alcohol consumption and ADHD symptoms.

Methods

Adults with an ADHD diagnosis (n = 235, 41.3% males) and controls (n = 184, 38% males) completed a questionnaire assessing insomnia (Bergen Insomnia Scale), alcohol consumption (Alcohol Use Disorders Identification Test), and current ADHD symptoms (Adult ADHD Self-report Scale). The majority of the sample (95%) gave additional information about childhood ADHD symptoms (Wender Utah Rating Scale), and information about lifetime occurrence of an internalizing disorder was included as part of background information.

Results

Compared to controls, the ADHD group reported a higher frequency of insomnia, a higher quantity of consumed alcohol and a higher frequency of internalizing disorders. Current and childhood ADHD symptoms were more severe in those with than without insomnia. Scores on ADHD symptom scales were explained by the presence of insomnia and internalizing disorders, while the contribution from alcohol consumption was restricted to the control group.

Discussion

The high functional impact of insomnia, alcohol misuse and internalizing disorders is well known. The present study contributed by focusing on their relations to ADHD symptoms, and by showing that strong relations were not restricted to adults with a clinical ADHD diagnosis. By this, the results put a critical light on a categorical delineation between adults with an ADHD diagnosis and population selected controls, and call for further studies including dimensional metrics of ADHD symptoms and co-occurring problems.

Validity and accuracy of the Adult Attention-Deficit/Hyperactivity Disorder (ADHD) Self-Report Scale (ASRS) and the Wender Utah Rating Scale (WURS) symptom checklists in discriminating between adults with and without ADHD

OBJECTIVE

To validate the Adult ADHD Self-Report Scale (ASRS) and the Wender Utah Rating Scale (WURS) in a well-characterized sample of adult attention-deficit/hyperactivity disorder (ADHD) patients and population controls.

METHODS

Both the ASRS and the WURS were administered to clinically diagnosed adult ADHD patients (n = 646) and to population controls (n = 908). We performed principal component analyses (PCA) and calculated receiver operating curves (ROC) including area under the curve (AUC) for the full WURS and ASRS, as well as for the PCA generated factors and the ASRS short screener.

RESULTS

We found an AUC of 0.956 (95% CI: 0.946-0.965) for the WURS, and 0.904 (95% CI: 0.888-0.921) for the ASRS. The ASRS short screener had an AUC of 0.903 (95%CI: 0.886-0.920). Combining the two full scales gave an AUC of 0.964 (95% CI: 0.955-0.973). We replicated the two-factor structure of the ASRS and found a three-factor model for the WURS.

CONCLUSION

The WURS and the ASRS both have high diagnostic accuracy. The short ASRS screener performed equally well as the full ASRS, whereas the WURS had the best discriminatory properties. The increased diagnostic accuracy may be due to the wider symptom range of the WURS and/or the retrospective childhood frame of symptoms.

The Attention Network Test Database: ADHD and Cross-Cultural Applications

Attention is a central component of cognitive and behavioral processes and plays a key role in basic and higher-level functioning. Posner's model of attention describes three components or networks of attention: the alerting, which involves high intensity states of arousal; the orienting, which involves the selective direction of attention; and the executive control, which involves cognitive functions such as conflict resolution and working memory. The Attention Network Test (ANT) is a computerized testing measure that was developed to measure these three networks of attention. This project describes the ANT, its widely used variants, and the recently developed ANT Database, a repository of data extracted from all studies that have used the ANT as of 2019. To illustrate the potential uses of the database, two meta-analyses conducted using the ANT Database are described. One explores task performance in children with and without attention deficit/hyperactivity disorder (ADHD). The other one explores regional differences between studies conducted in China, Europe, and the United States. We are currently in the process of integrating the database into a publicly available web interface. When that work is complete, researchers, clinicians, and the general public will be able to use the database to explore topics of interest related to attention.

Attention as neurocognitive endophenotype of ADHD across the life span: a family study

Endophenotypes mediate pathways between genetic variations and the psychiatric phenotype, or share genetic risk with the psychiatric phenotype. Identifying endophenotypes is an important step to unravel disease pathways underlying complex psychiatric phenotypes such as ADHD. Potential viable endophenotypes for ADHD across the lifespan are neurocognitive measures of basic attention functions, such as sustained attention, and executive attention functions (EF), such as inhibition. The present study evaluated the endophenotype criteria of familiality and state-independency for measures of basic attention and EF in affected- and unaffected parents of children with ADHD (N = 139), and typically developing children (N = 60). In addition, the added value of neurocognitive measures relative to questionnaire data in genetically informed designs was explored by comparing the intergenerational transmission of neurocognitive measures to those of ADHD symptom scores. Results revealed small-to-medium-sized familial effects of ADHD for reaction time measures of EF components and state-independency given familial effects. Parent-child correlations as estimates of intergenerational transmission of those neurocognitive measures were not higher than those of behavioral ADHD symptom ratings. Taken together, our results argue against neurocognitive measures as pivotal endophenotypes for ADHD across the lifespan. If studied as neurocognitive endophenotypes of ADHD in adults, reaction time measures of executive-rather than basic attention function-seem to be more sensitive.

Verbal Memory Function in Intellectually Well-Functioning Adults With ADHD: Relations to Working Memory and Response Inhibition

Objective: To investigate verbal memory function with relation to working memory (WM) and response inhibition (RI) in adults with ADHD. Method: Verbal memory function was assessed by the California Verbal Learning Test-Second Edition (CVLT-II), WM by the Paced Serial Addition Test, and RI by the Color-Word Interference Test from Delis-Kaplan Executive Function System in a sample of adults with normal to high intellectual function (IQ). Results: The ADHD group (n = 74) obtained lower scores than controls on measures of learning, recall, and immediate memory (CVLT-II). WM and RI explained a substantial part of verbal memory performance in both groups. A group to executive function (EF) interaction effect was identified for the total number of intrusions and false positive responses on the CVLT-II recognition trial. Conclusion: Verbal memory performance only partially overlaps with EF in intellectually well-functioning adults with ADHD. Both EF and verbal memory function should be assessed as part of a neuropsychological evaluation of adults with ADHD. (J. of Att. Dis. XXXX; XX(X) XX-XX).

Selective Impairment of Attentional Networks of Executive Control in Middle-Aged Subjects with Type 2 Diabetes Mellitus

Background

The influence of type 2 diabetes mellitus (T2DM) on attention has been elusive. The Attention Network Test (ANT) was developed to evaluate the functioning of 3 individual attentional networks: orienting, alerting, and executive control. The purpose of this study was to use the ANT to assess attentional function and its sub-components in T2DM patients ages 40–60 years.

Material/Methods

Thirty T2DM patients and 30 healthy controls ages 40–60 years were recruited in this investigation. The ANT was used to statistically compare the efficiency among 3 sub-components of the attention networks between middle-aged T2DM patients (n=30) and gender-, age-, and education-matched healthy controls (n=30).

Results

The ANT demonstrated a significant difference in executive control network between the T2DM patients and healthy controls (t=3.242, P=0.002), whereas no significant difference was observed regarding the domains of alerting (t=0.515, P=0.609) and orienting control (t=0.078, P=0.938) between the T2DM patient group and the healthy control group. Moreover, the mean reaction time in the ANT in the T2DM patients was significantly longer compared with that in the healthy controls (t=3.561, P=0.001).

Conclusions

The ANT reveals significant impairment in the executive control of middle-aged patients diagnosed with T2DM, whereas no significant impairment was observed in the domains of alerting and orienting.

Implicit and Explicit Number-Space Associations Differentially Relate to Interference Control in Young Adults With ADHD

Behavioral evidence for the link between numerical and spatial representations comes from the spatial-numerical association of response codes (SNARC) effect, consisting in faster reaction times to small/large numbers with the left/right hand respectively. The SNARC effect is, however, characterized by considerable intra- and inter-individual variability. It depends not only on the explicit or implicit nature of the numerical task, but also relates to interference control. To determine whether the prevalence of the latter relation in the elderly could be ascribed to younger individuals' ceiling performances on executive control tasks, we determined whether the SNARC effect related to Stroop and/or Flanker effects in 26 young adults with ADHD. We observed a divergent pattern of correlation depending on the type of numerical task used to assess the SNARC effect and the type of interference control measure involved in number-space associations. Namely, stronger number-space associations during parity judgments involving implicit magnitude processing related to weaker interference control in the Stroop but not Flanker task. Conversely, stronger number-space associations during explicit magnitude classifications tended to be associated with better interference control in the Flanker but not Stroop paradigm. The association of stronger parity and magnitude SNARC effects with weaker and better interference control respectively indicates that different mechanisms underlie these relations. Activation of the magnitude-associated spatial code is irrelevant and potentially interferes with parity judgments, but in contrast assists explicit magnitude classifications. Altogether, the present study confirms the contribution of interference control to number-space associations also in young adults. It suggests that magnitude-associated spatial codes in implicit and explicit tasks are monitored by different interference control mechanisms, thereby explaining task-related intra-individual differences in number-space associations.

Possible Medication-Resistant Deficits in Adult ADHD

OBJECTIVE

The nature of ADHD, especially in adulthood, is not well-understood. Therefore, we explored subcomponents of attention in adult ADHD.

METHOD

Twenty-three adults with ADHD were tested on neurocognitive and visual tracking performance both while on their regular prescription stimulant medication and while abstaining from the medication for 1 day. Pairwise comparisons to 46 two-for-one matched normal controls were made to detect medication-resistant effects of ADHD, and within-participant comparisons were made to detect medication-sensitive effects in patients.

RESULTS

Even when on medication, patients performed more poorly than controls on a spatial working memory task, and on visual tracking and simple reaction time tasks immediately following other attention-demanding tasks. Patients' visual tracking performance degraded while off-medication in a manner consistent with reduced vigilance.

CONCLUSION

There may be persistent cognitive impairments in adult ADHD despite medication. In addition, the benefit of stimulants seems reduced under cognitive fatigue.

Inattention in primary school is not good for your future school achievement-A pattern classification study

Inattention in childhood is associated with academic problems later in life. The contribution of specific aspects of inattentive behaviour is, however, less known. We investigated feature importance of primary school teachers’ reports on nine aspects of inattentive behaviour, gender and age in predicting future academic achievement. Primary school teachers of n = 2491 children (7–9 years) rated nine items reflecting different aspects of inattentive behaviour in 2002. A mean academic achievement score from the previous semester in high school (2012) was available for each youth from an official school register. All scores were at a categorical level. Feature importances were assessed by using multinominal logistic regression, classification and regression trees analysis, and a random forest algorithm. Finally, a comprehensive pattern classification procedure using k-fold cross-validation was implemented. Overall, inattention was rated as more severe in boys, who also obtained lower academic achievement scores in high school than girls. Problems related to sustained attention and distractibility were together with age and gender defined as the most important features to predict future achievement scores. Using these four features as input to a collection of classifiers employing k-fold cross-validation for prediction of academic achievement level, we obtained classification accuracy, precision and recall that were clearly better than chance levels. Primary school teachers’ reports of problems related to sustained attention and distractibility were identified as the two most important features of inattentive behaviour predicting academic achievement in high school. Identification and follow-up procedures of primary school children showing these characteristics should be prioritised to prevent future academic failure.

Connectome-based Models Predict Separable Components of Attention in Novel Individuals

Although we typically talk about attention as a single process, it comprises multiple independent components. But what are these components, and how are they represented in the functional organization of the brain? To investigate whether long-studied components of attention are reflected in the brain's intrinsic functional organization, here we apply connectome-based predictive modeling (CPM) to predict the components of Posner and Petersen's influential model of attention: alerting (preparing and maintaining alertness and vigilance), orienting (directing attention to a stimulus), and executive control (detecting and resolving cognitive conflict) [Posner, M. I., & Petersen, S. E. The attention system of the human brain. Annual Review of Neuroscience, 13, 25-42, 1990]. Participants performed the Attention Network Task (ANT), which measures these three factors, and rested during fMRI scanning. CPMs tested with leave-one-subject-out cross-validation successfully predicted novel individual's overall ANT accuracy, RT variability, and executive control scores from functional connectivity observed during ANT performance. CPMs also generalized to predict participants' alerting scores from their resting-state functional connectivity alone, demonstrating that connectivity patterns observed in the absence of an explicit task contain a signature of the ability to prepare for an upcoming stimulus. Suggesting that significant variance in ANT performance is also explained by an overall sustained attention factor, the sustained attention CPM, a model defined in prior work to predict sustained attentional abilities, predicted accuracy, RT variability, and executive control from task-based data and predicted RT variability from resting-state data. Our results suggest that, whereas executive control may be closely related to sustained attention, the infrastructure that supports alerting is distinct and can be measured at rest. In the future, CPM may be applied to elucidate additional independent components of attention and relationships between the functional brain networks that predict them.

Executive Dysfunctions: The Role in Attention Deficit Hyperactivity and Post-traumatic Stress Neuropsychiatric Disorders

Executive functions (EFs) is an umbrella term for various cognitive processes controlled by a complex neural activity, which allow the production of different types of behaviors seeking to achieve specific objectives, one of them being inhibitory control. There is a wide consensus that clinical and behavioral alterations associated with EF, such as inhibitory control, are present in various neuropsychiatric disorders. This paper reviews the research literature on the relationship between executive dysfunction, frontal-subcortical neural circuit changes, and the psychopathological processes associated with attention deficit hyperactivity disorder (ADHD) and post-traumatic stress disorder (PTSD). A revision on the role of frontal-subcortical neural circuits and their presumable abnormal functioning and the high frequency of neuropsychiatric symptoms could explain the difficulties with putting effector mechanisms into action, giving individuals the necessary tools to act efficiently in their environment. Although, neuronal substrate data about ADHD and PTSD has been reported in the literature, it is isolated. Therefore, this review highlights the overlapping of neural substrates in the symptomatology of ADHD and PTSD disorders concerning EFs, especially in the inhibitory component. Thus, the changes related to impaired EF that accompany disorders like ADHD and PTSD could be explained by disturbances that have a direct or indirect impact on the functioning of these loops. Initially, the theoretical model of EF according to current neuropsychology will be presented, focusing on the inhibitory component. In a second stage, this component will be analyzed for each of the disorders of interest, considering the clinical aspects, the etiology and the neurobiological basis. Additionally, commonalities between the two neuropsychiatric conditions will be taken into consideration from the perspectives of cognitive and emotional inhibition. Finally, the implications and future prospects for research and interventions in the area will be outlined, with the intention of contributing scientific reference information that encompasses the knowledge and understanding of executive dysfunction and its relationship with these treated disorders.

Linear and non-linear analyses of Conner's Continuous Performance Test-II discriminate adult patients with attention deficit hyperactivity disorder from patients with mood and anxiety disorders

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a heterogeneous disorder. Therefore it is important to look for factors that can contribute to better diagnosis and classification of these patients. The aims of the study were to characterize adult psychiatric out-patients with a mixture of mood, anxiety and attentional problems using an objective neuropsychological test of attention combined with an assessment of mood instability.

METHOD

Newly referred patients (n = 99; aged 18-65 years) requiring diagnostic evaluation of ADHD, mood or anxiety disorders were recruited, and were given a comprehensive diagnostic evaluation including the self-report form of the cyclothymic temperament scale and Conner's Continuous Performance Test II (CPT-II). In addition to the traditional measures from this test we have extracted raw data and analysed time series using linear and non-linear mathematical methods.

RESULTS

Fifty patients fulfilled criteria for ADHD, while 49 did not, and were given other psychiatric diagnoses (clinical controls). When compared to the clinical controls the ADHD patients had more omission and commission errors, and higher reaction time variability. Analyses of response times showed higher values for skewness in the ADHD patients, and lower values for sample entropy and symbolic dynamics. Among the ADHD patients 59 % fulfilled criteria for a cyclothymic temperament, and this group had higher reaction time variability and lower scores on complexity than the group without this temperament.

CONCLUSION

The CPT-II is a useful instrument in the assessment of ADHD in adult patients. Additional information from this test was obtained by analyzing response times using linear and non-linear methods, and this showed that ADHD patients with a cyclothymic temperament were different from those without this temperament.

Co-occurring symptoms of attention deficit hyperactivity disorder (ADHD) in a population-based sample of adolescents screened for depression

BACKGROUND

Depression is common in adolescents, with a gender bias towards girls. Symptoms associated with attention deficit hyperactivity disorder (ADHD) tend to co-occur in depressed adolescents. This may be related to common features between the two symptom domains, but co-occurring ADHD symptoms may also inflate the severity of depression. The present study investigates the frequency and influence of ADHD symptoms co-occurring with depression in a gender balanced population-based sample of Norwegian adolescents.

METHODS

A sample of 9614 adolescents (16-19 years) completed a questionnaire including the short version of the Mood and Feelings Questionnaire (sMFQ) and the Adult ADHD Self-Report Scale (ASRS), with items reflecting symptoms associated with depression and ADHD, respectively. The sMFQ sum score was used as a proxy for severity of depression, and adolescents with a score equal to or above the 90th percentile were defined as depressed. A high response on any of the ASRS items was used to define the presence of an ADHD symptom, and the number of high scores was used to indicate severity.

RESULTS

ADHD symptoms were frequently reported by the adolescents, with a higher frequency in girls than in boys. The gender differences were, however, minor when the analysis was restricted to the adolescents defined as depressed. Each severe symptom reported on the ASRS contributed significantly to increase the sum score on the sMFQ, and more than 20 % of the adolescents defined as depressed reported six or more symptoms within the ASRS inattention subscale.

CONCLUSIONS

The results emphasize the importance of screening for symptoms associated with ADHD when assessing adolescents presenting symptoms indicating depression. Although girls reported higher frequency of symptoms within both domains, the gender bias was dependent on the overall symptom severity. Awareness of co-occurrence of symptoms and gender biases are of importance for both clinical work and future research on mental health and service use in adolescence.

Establishing the Attention-Distractibility Trait

Failures to focus attention will affect any task engagement (e.g., at work, in the classroom, when driving). At the clinical end, distractibility is a diagnostic criterion of attention-deficit/hyperactivity disorder (ADHD). In this study, we examined whether the inability to maintain attentional focus varies in the overall population in the form of an attention-distractibility trait. To test this idea, we administered an ADHD diagnostic tool to a sample of healthy participants and assessed the relationship between ADHD symptoms and task distraction. ADHD symptom summary scores were significantly positively associated with distractor interference in letter-search and name-classification tasks (as measured by reaction time), as long as the distractors were irrelevant (cartoon images) rather than relevant (i.e., compatible or incompatible with target names). Higher perceptual load during a task eliminated distraction irrespective of ADHD score. These findings suggest the existence of an attention-distractibility trait that confers vulnerability to irrelevant distraction, which can be remedied by increasing the level of perceptual load during the task.

A Randomized, Double-Blind, Sham-Controlled Trial of Transcranial Direct Current Stimulation in Attention-Deficit/Hyperactivity Disorder

Background

Current standardized treatments for cognitive impairment in attention-deficit/hyperactivity disorder remain limited and their efficacy restricted. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in several neuropsychiatric disorders. Nevertheless, the effects of tDCS in reducing cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD) have not yet been investigated.

Methods

A parallel, randomized, double-blind, sham-controlled trial was conducted to examine the efficacy of tDCS on the modulation of inhibitory control in adults with ADHD. Thirty patients were randomly allocated to each group and performed a go/no-go task before and after a single session of either anodal stimulation (1 mA) over the left dorsolateral prefrontal cortex or sham stimulation.

Results

A nonparametric two-sample Wilcoxon rank-sum (Mann-Whitney) test revealed no significant differences between the two groups of individuals with ADHD (tDCS vs. sham) in regard to behavioral performance in the go/no go tasks. Furthermore, the effect sizes of group differences after treatment for the primary outcome measures—correct responses, impulsivity and omission errors—were small. No adverse events resulting from stimulation were reported.

Conclusion

According to these findings, there is no evidence in support of the use of anodal stimulation over the left dorsolateral prefrontal cortex as an approach for improving inhibitory control in ADHD patients. To the best of our knowledge, this is the first clinical study to assess the cognitive effects of tDCS in individuals with ADHD. Further research is needed to assess the clinical efficacy of tDCS in this population.

Trial Registration

ClinicalTrials.gov NCT01968512

Deciphering interference control in adults with ADHD by using distribution analyses and electromyographic activity

A deficit in "interference control" is commonly found in adults with Attention Deficit Hyperactivity Disorder (ADHD). This has mainly been interpreted as difficulties in inhibiting inappropriate responses. However, interference control involves processes other than simply the ability to inhibit. Consequently, we used sophisticated analysis to decipher the additional processes of interference control in these patients. We compared interference control between 16 adults with ADHD and 15 control adults performing a Simon task. In most studies, performance is generally reported in terms of mean error rates and reaction times (RTs). However, here we used distribution analyses of behavioral data, complemented by analyses of electromyographic (EMG) activity. This allowed us to better quantify the control of interference, specifically the part that remains hidden when pure correct trials are not distinguished from partial errors. Partial errors correspond to sub-threshold EMG bursts induced by incorrect responses that immediately precede a correct response. Moreover, besides "online" control, we also investigated cognitive control effects manifesting across consecutive trials. The main findings were that adults with ADHD were slower and showed a larger interference effect in comparison to controls. However, the data revealed that the larger interference effect was due neither to higher impulse expression, nor to a deficit in inhibition but that these patients presented a larger interference effect than the controls after congruent trials. We propose and discuss the hypothesis that the interference control deficit found in adults with ADHD is secondary to impairments in sustained attention.

Mindfulness Meditation Improves Mood, Quality of Life, and Attention in Adults with Attention Deficit Hyperactivity Disorder

OBJECTIVE

Adults with attention deficit hyperactivity disorder (ADHD) display affective problems and impaired attention. Mood in ADHD can be improved by mindful awareness practices (MAP), but results are mixed regarding the enhancement of attentional performance. Here we evaluated MAP-induced changes in quality of life (QoL), mood, and attention in adult ADHD patients and controls using more measures of attention than prior studies.

METHODS

Twenty-one ADHD patients and 8 healthy controls underwent 8 weekly MAP sessions; 22 similar patients and 9 controls did not undergo the intervention. Mood and QoL were assessed using validated questionnaires, and attention was evaluated using the Attentional Network Test (ANT) and the Conners Continuous Performance Test (CPT II), before and after intervention.

RESULTS

MAP enhanced sustained attention (ANT) and detectability (CPT II) and improved mood and QoL of patients and controls.

CONCLUSION

MAP is a complementary intervention that improves affect and attention of adults with ADHD and controls.

Contribution of transcranial direct current stimulation on inhibitory control to assess the neurobiological aspects of attention deficit hyperactivity disorder: randomized controlled trial

Background

The applicability of transcranial direct current stimulation (tDCS) in individuals with attention deficit hyperactivity disorder (ADHD) has not yet been investigated. This low-cost, non-invasive, and safe technique optimized to modulate the inhibitory response might be a useful treatment option for those affected by this condition.

Objective

The aim of this single center, parallel, randomized, double-blinded, sham-controlled trial is to investigate the efficacy of transcranial direct current stimulation over the prefrontal cortex on the modulation of inhibitory control in adults with attention deficit hyperactivity disorder.

Methods

A total of 60 individuals will be divided into 2 groups by block randomization to receive active or sham stimulation. Anodal stimulation over the left dorsolateral prefrontal cortex will be applied at 1 mA during a single 20-minute session. Before and after interventions, subjects will perform 2 go/no go tasks and the brain electrical activity will be recorded by electroencephalogram (EEG) with 32 channels, according to the 10-20 international EEG system.

Results

The trial began in May 2013 and we are currently performing the statistical analysis for the secondary outcomes.

Conclusions

The findings from this study will provide preliminary results about the role of prefrontal cortex activation through tDCS on ADHD patients.

Trial Registration

Clinicaltrials.gov NCT01968512; http://clinicaltrials.gov/ct2/show/NCT01968512 (Archived by WebCite at www.webcitation.org/6YMSW2tkD).

Neurobiological and behavioural studies of affective instability in clinical populations: a systematic review

OBJECTIVES

To evaluate the neurobiological, psychophysical and behavioural measures of affective instability in clinical populations.

DATA SOURCES

A range of medical and psychological science electronic databases were searched (including MEDLINE, EMBASE, and PsycINFO). Hand searching and reference checking are also included.

REVIEW METHODS

Reviews, systematic reviews, experimental and cross-sectional studies, providing affective instability in neurobiological and behavioural measurements in clinical populations. Studies were selected, data were extracted and quality was appraised.

RESULTS

Twenty-nine studies were included, 6 of which were review studies (one a meta-analysis) and 23 of which were primary studies, across a wide variety of disorders including ADHD, bipolar affective disorder, schizophrenia, severe mood dysregulation, major depression, and borderline personality disorder.

CONCLUSIONS

The bulk of the studies converge on the role of the amygdala, particularly in borderline personality disorders, and how it connects with other areas of the brain. Future research needs to extend these findings across diagnoses and development.

Selective impairment of attentional networks of alerting in Wilson's disease

Wilson's disease (WD) is typically affected by attention, which is one of the cognitive domains. The Attention Network Test (ANT) was developed to measure the functioning of the following three individual attentional networks: orienting, alerting, and executive control. The ANT has been used in a variety of neuropsychiatric conditions; however, it has not been used in WD. The aim of this study was to investigate the attentional function of WD patients, and 35 patients with early and moderate neurological WD, as well as 35 gender-, age-, and education-matched healthy controls performed the ANT. Remarkable differences between the patients and healthy controls were observed in the alerting network (p = 0.007) in contrast the differences in the orienting (p = 0.729) and executive control (p = 0.888) networks of visual attention. The mean reaction time in the ANT was significantly longer in the WD patients than in the controls (p<0.001, 0.001). In the WD patients, there was an effect specifically on the alerting domain of the attention network, whereas the orienting and executive control domains were not affected.

The association of ADHD symptoms to self-harm behaviours: a systematic PRISMA review

BACKGROUND

Self-harm is a major public health issue in young people worldwide and there are many challenges to its management and prevention. Numerous studies have indicated that ADHD is associated with completed suicides and other suicidal behaviours (i.e., suicidal attempt and ideation). However, significantly less is known about the association between ADHD and self-harm.

METHOD

This is the first review of the association between ADHD and self-harm. A systematic PRISMA review was conducted. Two internet-based bibliographic databases (Medline and CINAHL) were searched to access studies which examined to any degree the association between, specifically, ADHD and self-harm.

RESULTS

Only 15 studies were identified which investigated the association between ADHD and self-harm and found evidence to support that ADHD is a potential risk factor for self-harm.

CONCLUSION

This association raises the need for more awareness of self-harm in individuals with symptoms of ADHD.

Acetylcholine-metabolizing butyrylcholinesterase (BCHE) copy number and single nucleotide polymorphisms and their role in attention-deficit/hyperactivity syndrome

A previous genome-wide screen for copy number variations (CNVs) in attention deficit/hyperactivity disorder (ADHD) revealed a de novo chromosome 3q26.1 deletion in one of the patients. Candidate genes at this locus include the acetylcholine-metabolizing butyrylcholinesterase (BCHE) expressing gene (OMIM #177400), which is of particular interest. The present study investigates the hypothesis that the heterozygous deletion of the BCHE gene is associated with adult ADHD (aADHD). Ina first step, we screened 348 aADHD patients and 352 controls for stretches of loss of heterozygosity (LOH) across the entire BCHE gene to screen for the deletion. Our second aim was to clarify whether BCHE single nucleotide polymorphisms (SNPs) themselves influence the risk towards ADHD. Putative functional consequences of associated SNPs as well as their un-typed proxies were predicted by several bioinformatic tools. 96 individuals displayed entirely homozygous genotype reads in all 12 examined SNPs, making them possible candidates to harbor a heterozygous BCHE deletion. DNA from these 96 probands was further analyzed by real-time PCR using a BCHE-specific CNV assay. However, no deletion was found. Of the 12 tag SNPs that passed inclusion criteria, rs4680612 and rs829508 were significantly associated with aADHD, as their minor alleles occurred more often in cases than in controls (p = 0.018 and p = 0.039, respectively). The risk variant rs4680612 is located in the transcriptional control region of the gene and predicted to disrupt a binding site for MYT-1, which has previously been associated with mental disorders. However, when examining a second independent adult ADHD sample of 353 cases, the association did not replicate. When looking up the deletion in three genome-wide screens for CNV in ADHD and combining it with the present study, it became apparent that 3 from a total of 1030 ADHD patients, but none of 5787 controls, featured a deletion of the BCHE promoter region including rs4680612 (p = 0.00004). Taken together, there are several lines of evidence suggesting a potential involvement of BCHE in the etiopathology of ADHD, as a rare hemizygous deletion as well as a common SNP in the same region are associated with disease, although with different penetrance. Both variations result in the disruption of the binding site of the transcription factor MYT-1 suggesting epistatic effects of BCHE and MYT-1 in the pathogenesis of ADHD. As we were not able to replicate the SNP association, our findings should be considered preliminary and call for larger studies in extended phenotypes.

Interference control in adult ADHD: no evidence for interference control deficits if response speed is controlled by delta plots

Several theoretical accounts assume that interference control deficits belong to the core symptoms of adult ADHD. However, findings of increased interference effects in adult ADHD patients compared with healthy adults may be confounded with the simultaneous finding of generally slower responses in the patient group. The current study compared the magnitude of the interference effect in the Stroop task between a group of adults with ADHD and a healthy adult control group in a procedure that accounted for differences in overall response speed by using delta plots. The amount of interference did not differ between patient and control group at comparable reaction time levels. These results challenge the conclusions of the previous studies, in that they indicate that interference control is not impaired in adult ADHD.

The impact of passive hyperthermia on human attention networks: an fMRI study

An attention network test (ANT) provides a behavioral measure of the efficiency of the three attention networks (alerting, orienting and executive networks) within a single task. In the present study, we investigated the effect of passive hyperthermia on the attention network with event-related functional magnetic resonance imaging (fMRI). The behavioral results showed that passive hyperthermia of 50 °C and 40% relative humidity impaired the executive function, but showed no effect on the alerting and orienting networks. The fMRI results showed that: (i) passive hyperthermia enhanced the activity in the right superior frontal gyrus and depressed the activity in the right middle occipital gyrus, left inferior parietal lobule and left culmen in the alerting network, (ii) passive hyperthermia enhanced the activity in the temporal lobe and depressed the activity in the frontal lobe, parietal lobe and occipital lobe in the orienting network, and (iii) passive hyperthermia enhanced the activity in the dorsolateral prefrontal cortex but did not affect the activity in the anterior cingulate. We concluded that passive hyperthermia impaired executive function, especially the efficiency of resolving conflict and the negative effects of passive hyperthermia on alerting and orienting were overcome through variant regional brain activation.

Hyperthermia impairs the executive function using the Attention Network Test

PURPOSE

The primary aim of this study was to examine the effect of passive hyperthermia on the human attention system using the Attention Network Test (ANT), which has been used in both healthy controls and patients. Using target contrasts between conditions within a Flanker paradigm, the ANT can isolate three essential networks in the attention system: maintaining an alert state that is receptive to stimulus input and ready for responding; orienting, which involves selection of sensory input; and executive control, which monitors for and resolves conflict in responding or other aspects of cognitive processing.

MATERIALS AND METHODS

The ANT was administered to 16 right-handed subjects in a heat stress condition (50°C, 40% relative humidity) and a control condition (20°C, 40% relative humidity), for 1 hour each. Reaction time (RT) and accuracy rate as well as mean body core temperature (T-core) and body weight loss were recorded.

RESULTS

Compared to the control condition, T-cores significantly increased and body weight was not significantly reduced in the heat stress condition. Overall, there were non-significant group differences for RT and accuracy rate. Although significant changes in neither alerting nor orienting effects were modulated by the simulated hyperthermia, the executive control effect on RTs was significantly larger in the heat compared to the control condition.

CONCLUSIONS

Passive hyperthermia impaired executive control function, whereas alerting and orienting effects were unaffected.

Set-shifting in adults with ADHD

Difficulties related to inhibition and set-shifting have been suggested as possible endophenotypes of Attention Deficit Hyperactivity Disorder (ADHD). However, such difficulties have not been consistently found in studies using standard neuropsychological tests. This has been partly explained by the complexity of these tests and the need to include contrast measures which control for more basic functions. The purpose of the present study was to examine whether difficulties related to inhibition and set-shifting in adult ADHD patients could be revealed by the Color Word Interference Test (CWIT) from the Delis Kaplan Executive Function System (D-KEFS). A clinically recruited group of adults with ADHD (n = 60) obtained significantly lower scores than population derived controls (n = 60) on both primary summary (p < .001) and contrast measures (p = .004) of set-shifting. The differences between the groups remained statistically significant after controlling for intellectual function and working memory (p = .003). However, no significant differences between the groups were observed on any measure of inhibition. The study indicates that adults with ADHD have specific difficulties with set-shifting as measured by the CWIT, difficulties that probably also reflect problems related to executive function in their daily life.

Are executive function and impulsivity antipodes? A conceptual reconstruction with special reference to addiction

RATIONALE

Although there is considerable interest in how either executive function (EF) or impulsivity relate to addiction, there is little apparent overlap between these research areas.

OBJECTIVES

The present paper aims to determine if components of these two constructs are conceptual antipodes--widely separated on a shared continuum.

METHODS

EFs and impulsivities were compared and contrasted. Specifically, the definitions of the components of EF and impulsivity, the methods used to measure the various components, the populations of drug users that show deficits in these components, and the neural substrates of these components were compared and contrasted.

RESULTS

Each component of impulsivity had an antipode in EF. EF, however, covered a wider range of phenomena, including compulsivity.

CONCLUSIONS

Impulsivity functions as an antipode of certain components of EF. Recognition of the relationship between EF and impulsivity may inform the scientific inquiry of behavioral problems such as addiction. Other theoretical implications are discussed.