Executive function and attention deficit hyperactivity disorder: stimulant medication and better executive function performance in children

Treatment Adherence and Related Factors Among Children with Attention-Deficit/Hyperactivity Disorder in Saudi Arabia

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood psychiatric disorder. It frequently persists into adulthood and is a risk factor for other mental disorders and adverse outcomes, mainly if not managed optimally. This study aimed to assess ADHD treatment adherence and explore the underlying causes of non-adherence in ADHD children in Saudi Arabia.

Methods

A cross-sectional study of a convenience sample of 221 participants. The survey included demographic characteristics of the child and parents, the child's medical history, quality of services evaluation, as well as medication adherence assessment by Medication Adherence Report Scale (MARS), the general beliefs about medicines questionnaire (General-BMQ), in addition to assessing the parents' beliefs about ADHD and provided/recommended treatment.

Results

The sample was primarily 6 to 8-year-old children (32.81%) and males (78.52%). Most subjects were prescribed extended-release agents (45.7%), and overall, high-quality services were provided to the patients. The adherence rate of ADHD patients to their medication was 89.77%. The mother's education correlated significantly with patient adherence (p=0.029), and the mother's age correlated significantly with their beliefs (p=0.021), in addition to the family income (0.033). Children on Methylphenidate Immediate Release had good compliance with the medication (p=0.008). Moreover, Methylphenidate Extended Release has shown continuity results, increasing the adherence rates (p=0.035).

Conclusion

ADHD medication adherence was high and associated with older age, educational status, and type of medication used. Physicians should consider these factors to improve adherence in their patients.

Thrsp Gene and the ADHD Predominantly Inattentive Presentation

There are three presentations of attention-deficit/hyperactivity disorder (ADHD): the predominantly inattention (ADHD-PI), predominantly hyperactive-impulsive (ADHD-HI), and combined (ADHD-C) presentations of ADHD. These may represent distinct childhood-onset neurobehavioral disorders with separate etiologies. ADHD diagnoses are behaviorally based, so investigations into potential etiologies should be founded on behavior. Animal models of ADHD demonstrate face, predictive, and construct validity when they accurately reproduce elements of the symptoms, etiology, biochemistry, and disorder treatment. Spontaneously hypertensive rats (SHR/NCrl) fulfill many validation criteria and compare well with clinical cases of ADHD-C. Compounding the difficulty of selecting an ideal model to study specific presentations of ADHD is a simple fact that our knowledge regarding ADHD neurobiology is insufficient. Accordingly, the current review has explored a potential animal model for a specific presentation, ADHD-PI, with acceptable face, predictive, and construct validity. The Thrsp gene could be a biomarker for ADHD-PI presentation, and THRSP OE mice could represent an animal model for studying this distinct ADHD presentation.

Executive Function in Autism: Association with ADHD and ASD Symptoms

There is substantial comorbidity between autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD), and there are well-documented executive functioning (EF) deficits in both populations. An important question concerns whether EF deficits in children with ASD are related to severity of ASD, ADHD, or both. We examined ADHD and ASD symptoms in relation to ratings of EF in the home and classroom. The sample comprised 64 children (55 males) diagnosed with ASD (mean age = 9.26 years; mean FSIQ = 92). Analyses indicated that parent and teacher ratings of EF (except Shift and Emotional Control) were consistently related to ADHD symptom severity, but not to ASD severity. Thus, functioning in the domains of Shift and Emotional control appear relatively spared, whereas performance in all other EF was impaired in relation to ADHD symptoms.

On the Treatment and Diagnosis of Attention Deficit Hyperactivity Disorder with EEG Assistance

Attention deficit hyperactivity disorder (ADHD) is a mental disorder most notable in children. The disease may affect the ability to focus and cause a physical and mental restlessness and risky behavior. Recommended treatment consists of stimulant administration and behavioral therapy. However, medicating children is problematic since there are indications that brain development is affected by ADHD medication agents. Therefore, behavioral therapy is the preferred approach in ADHD treatment for children. In order to monitor and optimize the success of such behavioral therapies, neuro-feedback methods can be used. The most notable technology used in such methods is Electroencephalography (EEG). In this article, an overview of the pathology of ADHD, EEG and its usage as a diagnostic and therapeutic tool in the context of ADHD is given. Based on that knowledge, novel EEG measurement modes, new development principles, and system on chip implementations are presented and discussed.

Exploring the relationship between ADHD, its common comorbidities, and their relationship to organizational skills

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder affecting numerous executive functioning skills, such as organizational skills. While the relationship between the inattention aspect of ADHD and poor organizational skills is well documented, it is still unclear if lower organizational skills are only associated with ADHD or if they are also associated with other comorbid disorders commonly diagnosed in conjunction with ADHD. The purpose of the present study is to investigate the relationship between organizational skills and ADHD in adults, as well as the impact of comorbid disorders on ADHD in relation to organizational skills.

METHODS

Four hundred seven (n = 201 with a diagnosis of ADHD) adults from the general population were recruited online. Participants completed a measure of organizational skills, measures assessing levels of ADHD, depression, and anxiety, and extensive demographic information related to their diagnosis of ADHD or other possible diagnosis.

RESULTS

Participants with a diagnosis of ADHD were significantly more likely to have a comorbid diagnosis of depression and/or anxiety. Organizational skills were significantly lower in individuals who reported having received a diagnosis of ADHD, but not in those with a past diagnosis of depression and anxiety. However, organizational skills were lower in individuals currently experiencing higher levels of depression and anxiety. The results of regression analyses suggest that levels of organizational skills are most strongly predicted by inattention and more weakly predicted by comorbid disorders.

DISCUSSION

These results highlight the centrality of organizational skills deficit in ADHD as well as the influence of the inattention component over other components commonly observed in ADHD on organizational skills. Suggestions for treatment of ADHD in adults are discussed.

Acute intranasal dopamine application counteracts the reversal learning deficit of spontaneously hypertensive rats in an attentional set-shifting task

RATIONALE

Studies on the attention-deficit/hyperactivity disorder (ADHD) have concluded that the disorder might be caused by a deficit in the inhibitory control of executive functions because of dopamine hypofunction. Recently, the intranasal route has emerged as an effective alternative means for sending dopamine directly to the brain. However, whether the treatment can ameliorate the deficits of inhibitory control in ADHD remains unknown.

OBJECTIVES

Investigating the effects of acute intranasal dopamine (IN-DA) on the inhibitory control of executive functions of an ADHD rodent model.

METHODS

We trained an animal model of ADHD, the spontaneously hypertensive rat (SHR), and Wistar rats as controls, in an attentional set-shifting task (ASST) in which dopamine (0.15 mg/kg, 0.3 mg/kg, or vehicle) was intranasally administered before the final test.

RESULTS

IN-DA application dose-dependently improved the performance and reduced errors of SHR in the initial reversal learning. The effect size was comparable to that of a peripheral injection of 0.6 mg/kg methylphenidate. In control Wistar rats, the highest dose of intranasal dopamine (0.3 mg/kg) induced deficits in the reversal learning of extradimensional discriminations.

CONCLUSIONS

The findings suggest that the IN-DA treatment has potential for use in the treatment of ADHD; however, caution must be exercised when determining the dosage to be administered, because too much dopamine may have negative effects.

Conditional Learning Deficits in Children with ADHD can be Reduced Through Reward Optimization and Response-Specific Reinforcement

When children with ADHD are presented with behavioral choices, they struggle more than Typically Developing [TD] children to take into account contextual information necessary for making adaptive choices. The challenge presented by this type of behavioral decision making can be operationalized as a Conditional Discrimination Learning [CDL] task. We previously showed that CDL is impaired in children with ADHD. The present study explores whether this impairment can be remediated by increasing reward for correct responding or by reinforcing correct conditional choice behavior with situationally specific outcomes (Differential Outcomes). An arbitrary Delayed Matching-To-Sample [aDMTS] procedure was used, in which children had to learn to select the correct response given the sample stimulus presented (CDL). We compared children with ADHD (N = 45) and TD children (N = 49) on a baseline aDMTS task and sequentially adapted the aDMTS task so that correct choice behavior was rewarded with a more potent reinforcer (reward manipulation) or with sample-specific (and hence response-specific) reinforcers (Differential Outcomes manipulation). At baseline, children with ADHD performed significantly worse than TD children. Both manipulations (reward optimization and Differential Outcomes) improved performance in the ADHD group, resulting in a similar level of performance to the TD group. Increasing the reward value or the response-specificity of reinforcement enhances Conditional Discrimination Learning in children with ADHD. These behavioral techniques may be effective in promoting the learning of adaptive behavioral choices in children with ADHD.

Is Methylphenidate Beneficial and Safe in Pharmacological Cognitive Enhancement?

Nootropics are drugs used to either treat or benefit cognition deficits. Among this class, methylphenidate is a popular agent, which acts through indirect dopaminergic and noradrenergic agonism and, therefore, is proposed to enhance performance in catecholamine-dependent cognitive domains such as attention, memory and prefrontal cortex-dependent executive functions. However, investigation into the efficacy of methylphenidate as a cognitive enhancer has yielded variable results across all domains, leading to debate within the scientific community surrounding its off-label use in healthy individuals seeking scholaristic benefit or increased productivity. Through analysis of experimental data and methodological evaluation, it is apparent that there are dose-, task- and domain-dependent considerations surrounding the use of methylphenidate in healthy individuals, whereby tailored dose administration is likely to provide benefit on an individual basis dependent on the domain of cognition in which benefit is required. Additionally, it is apparent that there are subjective effects of methylphenidate, which may increase user productivity irrespective of cognitive benefit. Whilst there is not extensive study in healthy older adults, it is plausible that there are dose-dependent benefits to methylphenidate in older adults in selective cognitive domains that might improve quality of life and reduce fall risk. Methylphenidate appears to produce dose-dependent benefits to individuals with attention-deficit/hyperactivity disorder, but the evidence for benefit in Parkinson's disease and schizophrenia is inconclusive. As with any off-label use of pharmacological agents, and especially regarding drugs with neuromodulatory effects, there are inherent safety concerns; epidemiological and experimental evidence suggests there are sympathomimetic, cardiovascular and addictive considerations, which might further restrict their use within certain demographics.

Executive functions in school children from Montevideo, Uruguay and their associations with concurrent low-level arsenic exposure

OBJECTIVE

Arsenic is a known childhood neurotoxicant, but its neurotoxicity at low exposure levels is still not well established. The aim of our cross-sectional study was to test the association between low-level arsenic exposure and executive functions (EF) among children in Montevideo. We also assessed effect modification by arsenic methylation capacity, a susceptibility factor for the health effects of arsenic, and by B-vitamin intake, which impacts arsenic methylation.

METHODS

Arsenic exposure was assessed as the specific gravity-adjusted sum of urinary arsenic metabolites (U-As) among 255 ~ 7 year-old children, and methylation capacity as the proportion of urinary monomethylarsonic acid (%MMA). Arsenic concentrations from kitchen water samples at participants' homes were assessed. B-vitamin intake was calculated from the average of two 24-hour dietary recalls. EF was measured using three tests from the Cambridge Neuropsychological Test Automated Battery- Stockings of Cambridge (SOC), Intra-dimensional/extra-dimensional shift task (IED), and Spatial Span (SSP). Generalized linear models assessed the association between U-As and EF measures; models were adjusted for age, sex, maternal education, possessions score, Home Observation for Measurement of the Environment Inventory score, season, and school clusters. Additional analyses were conducted to address issues of residual confounding and sample size. A "B-vitamin index" was calculated using principal component analysis. Effect modification by the index and urinary %MMA was assessed in strata split at the respective medians of these variables.

RESULTS

The median (range) U-As and water arsenic levels were 9.9 µg/L (2.2, 47.7) and 0.45 µg/L (0.1, 18.9) respectively, indicating that exposure originated mainly from other sources. U-As was inversely associated with the number of stages completed (β = -0.02; 95% CI: -0.03, -0.002) and pre-executive shift errors (β = -0.08; 95% CI: -0.14, -0.02) of the IED task, and span length of the SSP task (β = -0.01; 95% CI: -0.02, -0.004). There was no clear pattern of effect modification by B-vitamin intake or urinary %MMA.

CONCLUSION

Low-level arsenic exposure may adversely affect executive function among children but additional, including longitudinal, studies are necessary to confirm these findings.

Neural Correlates of the Dual-Pathway Model for ADHD in Adolescents

OBJECTIVE

The dual-pathway model has been proposed to explain the heterogeneity in symptoms of attention deficit hyperactivity disorder (ADHD) by two independent psychological pathways based on distinct brain circuits. The authors sought to test whether the hypothesized cognitive and motivational pathways have separable neural correlates.

METHODS

In a longitudinal community-based cohort of 1,963 adolescents, the neuroanatomical correlates of ADHD were identified by a voxel-wise association analysis and then validated using an independent clinical sample (99 never-medicated patients with ADHD, 56 medicated patients with ADHD, and 267 healthy control subjects). The cognitive and motivational pathways were assessed by neuropsychological tests of working memory, intrasubject variability, stop-signal reaction time, and delay discounting. The associations were tested between the identified neuroanatomical correlates and both ADHD symptoms 2 years later and the polygenic risk score for ADHD.

RESULTS

Gray matter volumes of both a prefrontal cluster and a posterior occipital cluster were negatively associated with inattention. Compared with healthy control subjects, never-medicated patients, but not medicated patients, had significantly lower gray matter volumes in these two clusters. Working memory and intrasubject variability were associated with the posterior occipital cluster, and delay discounting was independently associated with both clusters. The baseline gray matter volume of the posterior occipital cluster predicted the inattention symptoms in a 2-year follow-up and was associated with the genetic risk for ADHD.

CONCLUSIONS

The dual-pathway model has both shared and separable neuroanatomical correlates, and the shared correlate in the occipital cortex has the potential to serve as an imaging trait marker of ADHD, especially the inattention symptom domain.

Attention-deficit/hyperactivity disorder in children and adolescents: An event-related potential study of working memory

Working memory (WM) impairments have been frequently observed as an important feature of attention-deficit/hyperactivity disorder (ADHD). Event-related potential (ERP) differences between ADHD and healthy controls (HC) would be expected during WM task performance. Especially, the so-called slow wave (SW), which is related to the retention process, might present amplitude differences in ADHD. In this ERP study participated twenty-nine ADHD children and adolescents and thirty-four HC. WM performance was assessed using the Working Memory Test Battery for Children (WMTB-C), and ERPs were analyzed with a Delayed Match-To-Sample (DMTS) task. ADHD sample showed worse behavioral performance in both WMTB-C and DMTS task, and higher SW amplitude during the retention phase of the DMTS task. Additionally, the principal component analysis indicated that the scores on the component explaining the centro-parietal SW were significantly different between ADHD subjects and HC. The observed impaired neurophysiological activity during the encoding and retention periods in ADHD, which would be the origin of the behavioral deficits in WM task performance, might be reflecting a delayed maturation of the neural processes underlying the centro-parietal SW.

The Effect of an Enriched Sport Program on Children's Executive Functions: The ESA Program

PURPOSE

The effects of physical exercise on executive functions (EFs) are well-documented. EFs are involved in daily activities, and their development determines the quality of people's future life, both in terms of mental health and quality of life. The purpose of the current paper is to evaluate the effects of a physical education program, elaborated within the Enriched Sports Activity Program (ESA Program), an Erasmus + Project, on EFs, namely, visuospatial working memory, inhibitory control, cognitive flexibility, and task switching.

METHOD

Data were collected on November 2017 (t1) and May 2018 (t2). At t1, a sample of 357 children from four European countries (Italy, Germany, Lithuania, and Turkey) performed a cognitive test battery made up of Digit Span Forward/Backward, Stroop Task, and Trail Making Test (TMT), whose order was randomized. From November until May, classrooms from the experimental group followed the ESA Program, while classrooms from the control continued with the ordinary physical education class. At t2, children from both experimental and control groups performed again the cognitive battery.

RESULT

The repeated measures ANOVA showed a significant effect of the ESA Program on the TMT B and on Digit Span Backward, but no significant effects were found on Digit Span Forward and Stroop Task.

CONCLUSION

The introduction of a sport program enriched with cognitive stimuli has beneficial effects for children working memory and cognitive flexibility.

Exploring the link between character, personality disorder, and neuropsychological function

Personality deviations and deficits in cognitive executive function are common among forensic populations. The present study on incarcerated offenders explored whether there are links between the two domains. Personality was assessed using the Temperament and Character Inventory (TCI). Neuropsychological performance, including visual working memory, attentional set-shifting and planning, were tested with the Cambridge Neuropsychological Test Automated Battery (CANTAB). Subjects with personality disorders scored high on harm avoidance, and low on self-directedness and cooperativeness. Personality disordered offenders did not differ from the comparison groups (offenders without personality disorder, and non-criminal controls) with regard to CANTAB measures of visual working memory (delayed matching to sample, spatial working memory) and planning (Stockings of Cambridge), but they made a larger number of errors on the attentional set-shifting task. Dimensional analysis of the personality and neuropsychological variables revealed significant associations between self-directedness and cooperativeness on the one hand, and attentional set-shifting on the other. Intellectually disabled, non-criminal individuals (marginal mental retardation) who performed poorly on attentional set-shifting also scored low on self-directedness and cooperativeness. The results indicate that poor development of certain personality traits may be associated with deficits in neuropsychological functioning.

Neurophysiological differences between ADHD and control children and adolescents during the recognition phase of a working memory task

Impairment of executive functions including attention and working memory (WM) have been proposed as an important feature of Attention Deficit and Hyperactivity Disorder (ADHD). During the recognition phase of a delayed match-to-sample test (DMTS) a reduced N2pc component, related to the attentional selection of the memorized item and a reduced distractor positivity (Pd), related to the processing suppression of distractors are expected in ADHD subjects. For the purpose of the study, twenty-nine ADHD subjects diagnosed with a structured interview and the DuPaul questionnaire, were included in the study. Thirty-four control subjects were recruited from public schools and matched by age (from 6 to 17 years old) and gender with the ADHD group. Reaction times (RTs), errors, and Event Related Potentials (ERPs) were obtained in a DMTS task during the recognition phase in correct trials. RTs and errors were higher in ADHD subjects compared to the control group. Specifically, errors were much higher in ADHD than in controls. The cluster mass permutation statistics showed a significant N2pc component in both groups during the recognition phase, but a significant Pd component was present only in controls. The present results suggest that in correct trials ADHD children use the same neural resources to select the memorized item from WM with similar efficacy than controls, although a lower Pd suggests a difficulty in suppressing distractors.

Distinct brain structure and behavior related to ADHD and conduct disorder traits

Attention-Deficit/Hyperactivity Disorder (ADHD) and conduct disorder (CD) exemplify top-down dysregulation conditions that show a large comorbidity and shared genetics. At the same time, they entail two different types of symptomology involving mainly non-emotional or emotional dysregulation. Few studies have tried to separate the specific biology underlying these two dimensions. It has also been suggested that both types of conditions consist of extreme cases in the general population where the symptoms are widely distributed. Here we test whether brain structure is specifically associated to ADHD or CD symptoms in a general population of adolescents (n = 1093) being part of the IMAGEN project. Both ADHD symptoms and CD symptoms were related to similar and overlapping MRI findings of a smaller structure in prefrontal and anterior cingulate cortex. However, our regions of interest (ROI) approach indicated that gray matter volume (GMV) and surface area (SA) in dorsolateral/dorsomedial prefrontal cortex and caudal anterior cingulate cortex were negatively associated to ADHD symptoms when controlling for CD symptoms while rostral anterior cingulate cortex GMV was negatively associated to CD symptoms when controlling for ADHD symptoms. The structural findings were mirrored in performance of neuropsychological tests dependent on prefrontal and anterior cingulate regions, showing that while performance on the Stop Signal test was specifically related to the ADHD trait, delayed discounting and working memory were related to both ADHD and CD traits. These results point towards a partially domain specific and dimensional capacity in different top-down regulatory systems associated with ADHD and CD symptoms.

New Insights on the Effects of Methylphenidate in Attention Deficit Hyperactivity Disorder

This narrative review describes an overview of the multiple effects of methylphenidate (MPH) in attention-deficit/hyperactivity disorder (ADHD) and its potential neurobiological targets. It addressed the following aspects: 1) MPH effects on attention and executive functions in ADHD; 2) the relation between MPH efficacy and dopamine transporter gene (DAT) polymorphism; and 3) the role of MPH as an epigenetic modulator in ADHD. Literature analysis showed that MPH, the most commonly used psychostimulant in the therapy of ADHD, acts on multiple components of the disorder. Marked improvements in attentional and executive dysfunction have been observed in children with ADHD during treatment with MPH, as well as reductions in neurological soft signs. MPH efficacy may be influenced by polymorphisms in the DAT, and better responses to treatment were associated with the 10/10 genotype. Innovative lines of research have suggested that ADHD etiopathogenesis and its neuropsychological phenotypes also depend on the expression levels of human endogenous retrovirus (HERV). In particular, several studies have revealed that ADHD is associated with HERV-H over-expression and that MPH administration results in decreased expression levels of this retroviral family and a reduction in the main symptoms of the disorder. In conclusion, there is a confirmed role for MPH as an elective drug in the therapy of ADHD alone or in association with behavioral therapy. Its effectiveness can vary based on DAT polymorphisms and can act as a modulator of HERV-H gene expression, pointing to targets for a precision medicine approach.

Clinical and Neuropsychological Predictors of Methylphenidate Response in Children and Adolescents with ADHD: A Naturalistic Follow-up Study in a Spanish Sample

BACKGROUND

Methylphenidate (MPH) is the most commonly used medication for Attention-Deficit/Hyperactivity Disorder (ADHD), but to date, there are neither consistent nor sufficient findings on conditions differentiating responsiveness to MPH response in ADHD.

OBJECTIVE

To develop a predictive model of MPH response, using a longitudinal and naturalistic follow-up study, in a Spanish sample of children and adolescents with ADHD.

METHODS

We included all children and adolescents with ADHD treated with MPH in our outpatient Clinic (2005 to 2015), evaluated with the K-SADS interview. We collected ADHD-RS-IV.es and CGI-S scores at baseline and at follow up, and neuropsychological testing (WISC-IV, Continuous Performance Test (CPT-II) & Stroop). Clinical response was defined as >30% reduction from baseline of total ADHD-RS-IV.es score and CGI-S final score of 1 or 2 maintained for the previous 3 months.

RESULTS

We included 518 children and adolescents with ADHD, mean (SD) age of patients was 11.4 (3.3) years old; 79% male; 51.7% had no comorbidities; and 75.31% had clinical response to a mean MPH dose of 1.2 mg/kg/day. Lower ADHD-RS-IV.es scores, absence of comorbidities (oppositional-defiant symptoms, depressive symptoms and alcohol/cannabis use), fewer altered neuropsychological tests, higher total IQ and low commission errors in CPT-II, were significantly associated with a complete clinical response to methylphenidate treatment.

CONCLUSION

Oppositional-defiant symptoms, depressive symptoms, and a higher number of impaired neuropsychological tests are associated with worse clinical response to methylphenidate. Other stimulants or non-stimulants treatment may be considered when these clinical and neuropsychological variables converged in the first clinical interview.

Relations between caregiver-report of sleep and executive function problems in children with autism spectrum disorder and attention-deficit/hyperactivity disorder

BACKGROUND

Many children with autism spectrum disorder (ASD) experience comorbid symptoms of attention-deficit/hyperactivity disorder (ADHD). Additionally, children with ASD and ADHD often have sleep disturbances and deficits in executive functioning (EF). In typical development, sleep disturbances are causally linked to EF deficits and exacerbate ADHD-like symptoms.

AIM

The aim of this study was to determine whether caregiver-report sleep and EF difficulties predict ADHD symptoms in children with ASD.

METHODS

Caregiver-report of child sleep, EF, and ADHD symptom severity was collected for 101 children with ASD, 7-11 years of age. Hierarchical linear regressions tested the independent and interactive effects of sleep and EF in predicting ADHD symptoms.

RESULTS

Children with ASD were more likely to have symptoms of ADHD if they experienced both sleep and EF difficulties. Children with difficulties in working memory were particularly at risk for clinically significant symptoms of ADHD. Notably, however, sleep did not mediate or moderate the relation between working memory and ADHD symptoms in this sample, suggesting that these variables act through independent mechanisms to increase vulnerability for comorbidity.

CONCLUSIONS

These results have clinical significance as sleep and EF deficits may identify an ASD subgroup that is at increased risk for a comorbid ADHD diagnosis.

Prefrontal Recruitment Mitigates Risk-Taking Behavior in Human Immunodeficiency Virus-Infected Young Adults

Background

Human immunodeficiency virus (HIV)-infected (HIV+) young adults often engage in risk-taking behavior. However, the disruptive effects of HIV on the neurobiological underpinnings of risky decision making are not well understood.

Methods

Risky decision making, measured via the Iowa Gambling Task (IGT), was compared voxel-wise to resting cerebral blood flow (rCBF) acquired via arterial spin labeling. Separate topographical maps were obtained for HIV-uninfected (HIV-; n = 62) and HIV+ (n = 41) young adults (18-24 years old) and were compared to the full cohort of participants. For the HIV+ group, rCBF was compared to recent and nadir CD4.

Results

IGT performance was supported by rCBF in 3 distinct brain regions: regions I, II, and III. The relationship between IGT performance and rCBF in HIV+ individuals was most robust in region I, the ventromedial prefrontal and insular cortices. Region II contained strong relationships for both HIV- and HIV+. Region III, dorsolateral prefrontal and posterior cingulate cortices, contained relationships that were strongest for HIV- controls. IGT performance was intact among HIV+ participants with higher rCBF in either region I or region III. By contrast, performance was worse among HIV+ individuals with lower rCBF in both regions I and III when compared to HIV- controls (P = .01). rCBF in region III was reduced in HIV+ compared with HIV- individuals (P = .04), and positively associated with nadir CD4 cell count (P = .02).

Conclusions

Recruitment of executive systems (region III) mitigates risk-taking behavior in HIV+ and HIV- individuals. Recruitment of reward systems (region I) mitigates risk-taking behavior when region III is disrupted due to immunological compromise. Identifying individual recruitment patterns may aid anatomically directed therapeutics or psychosocial interventions.

Executive Function and Attention Performance in Children with ADHD: Effects of Medication and Comparison with Typically Developing Children

The emerging literature reports that children with Attention-Deficit/Hyperactivity Disorder (ADHD) show deficits in executive functioning. To date, the combination of drug therapy with certain evidence-based non-medication interventions has been proven to be the most effective treatment for ADHD. There is a gap in the literature regarding comparing the executive functions (EF) of treatment naïve and medicated children with ADHD with both each other and typically developing children. Altogether, 50 treatment naïve and 50 medicated children with ADHD and 50 typically developing children between the ages of six and 12 were enrolled. The Mini International Neuropsychiatric Interview for Children and Adolescents (Mini Kid) and the Test of Attentional Performance for Children (KiTAP) measures were employed. Treatment naïve children with ADHD showed weaker performance on most executive function measures (12 out of 15) than either the medicated ADHD group or the controls. There were no significant differences between the medicated ADHD children and typically developing children in most KiTAP parameters (10 out of 15). Executive function impairments were observable in treatment naïve ADHD children, which draws attention to the importance of treating ADHD. Future studies should focus on the specific effects of stimulant medication on executive functions.

The effectiveness of methylphenidate in improving cognition after brain injury in adults: a systematic review

Objective: To conduct a systematic review investigating the effectiveness of methylphenidate in improving cognition following brain injury in an adult population.Data sources: CINAHL, PsychINFO, MEDLINE, and PubMed databases were searched for all relevant articles published from January 1980 up to December 2017.Study selection: Studies were included if participants had a diagnosis of new onset or previous acquired brain injury and were age 16 or over. Studies must have administered methylphenidate and measured its effectiveness on cognition using at least one measure of cognitive function.Data extraction: Data extracted included study design, sample size, participant characteristics, intervention method, outcome measures, and findings. The quality of included randomized controlled trials was assessed using the Physiotherapy Evidence Database. An overall level of evidence was assigned using a modified Sackett scale.Data synthesis: Included studies consisted of seven randomized controlled trials, two pre-post trials, one prospective controlled trial, and one case study. All included studies reported improved cognitive abilities following methylphenidate treatment post-injury.Conclusions: There is the strongest level of evidence (Level 1a) suggesting methylphenidate may alleviate cognitive impairments in adults with brain injury. However, longitudinal studies are warranted examining the effectiveness and safety of long-term methylphenidate use in this population.

Neuropsychological Performance Patterns of Adult ADHD Subtypes

Objective: Neuropsychological performance patterns associated with adult ADHD subtypes are unknown. The aim of the current systematic review was to identify and synthesize available literature regarding neuropsychological performance associated with adult ADHD subtypes. Method: Searches were completed using the databases PsycINFO and PubMed for studies published before March 2017 addressing adult ADHD subtypes and neuropsychological performance. Data characterizing the neuropsychological tests utilized in each study were obtained and sorted into eight domains. To summarize the results of all comparisons (ADHD subtype compared with control, or to each other), we counted the proportion of tests within each domain with significant group differences. Results/Conclusion: We deemed four domains informative in differentiating ADHD subtypes from controls. Of these, memory was the only domain that held promise in distinguishing ADHD-Inattentive and ADHD-Combined. Limitations of the available literature are highlighted and recommendations for future research are provided.

Impairments in resource allocation and executive control in children with ADHD

Children diagnosed with attention-deficit hyperactivity disorder (ADHD) show pronounced alterations in cognitive tasks, such as a highly variable mode of responding. There is an ongoing debate about the key driving mechanisms of such alterations (e.g. specific inhibition or working memory (WM) impairments or general impairments in the allocation of energetic resources). The aim of this study was to disentangle such process-specific versus general limitations in cognitive and energetic mechanisms in children with ADHD compared to typically developed (TD) children based on the performance in a task-switching paradigm. This paradigm allows for both a common measurement and a later segregation of different executive sub-processes. Task-switching performance, including performance variability, of 26 children diagnosed with combined-type ADHD (8-13 years) was compared against the performance of 26 age-matched/IQ-matched TD children. Results revealed that compared to TD children, ADHD-diagnosed children showed alterations in performance variability during task switching, both in general (indicating disturbances in resource allocation) and conditionally on WM demands (indicating a specific WM deficit). Hence, our study provides diagnostically relevant new insights into performance impairments in children with ADHD compared to TD children. Importantly, it seems mandatory to include information on performance variability when trying to phenotype alterations in cognitive performance in ADHD.

Beta band oscillatory deficits during working memory encoding in adolescents with attention-deficit hyperactive disorder

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioural disorder, characterized by symptoms of inattention and/or hyperactivity/impulsivity, in addition to various cognitive deficits, including working memory impairments. This pathology arises from a complex constellation of genetic, structural and neurotransmission abnormalities, which give rise to the aberrant electrophysiological patterns evident in patients with ADHD. Among such, findings have consistently provided support in favour of weaker power across the beta frequency range. Evidence has also emerged that beta rhythmic decrements are linked to working memory encoding. The catecholaminergic modulation of both working memory and beta oscillations may suggest that the link between the two might be rooted at the neurotransmission level. Studies have consistently shown that ADHD involves significant catecholaminergic dysregulation, which is also supported by other clinical studies that demonstrate stimulant-induced amelioration of ADHD symptomology. In this study, we explore the possible ways that might relate ADHD, working memory, beta rhythms and catecholaminergic signalling altogether by investigating the integrity of encoding-relevant electroencephalographic beta rhythms in medication-naïve and stimulant-medicated adolescent patients. The aberrant parietal and frontal encoding-related beta rhythm revealed in the ADHD patients together with a working memory (WM) deficit as observed herein was reversed by methylphenidate in the latter case but not with regard to the beta rhythm. This finding per se raises the issue of the role played by beta rhythms in the WM deficits associated with ADHD.

Light up ADHD: II. Neuropharmacological effects measured by near infrared spectroscopy: is there a biomarker?

BACKGROUND

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by deficits in self-controlling attention, behavior, and emotions. In recent years, noninvasive optical techniques, such as near infrared spectroscopy (NIRS), have been used to measure the neural correlates of pharmacological-therapy outcomes in children and adolescents with ADHD.

METHODS

We reviewed a short series of articles that investigated the results of functional NIRS (fNIRS) on developmental-age ADHD. The review was limited to fNIRS studies that investigated the cortical responses that occurred during neuropsychological tasks in ADHD patients who received methylphenidate or atomoxetine.

RESULTS

The majority of the reviewed studies revealed the presence of increased oxygenated hemoglobin concentrations in the prefrontal cortex following pharmacotherapy in ADHD samples. A higher frequency of right-lateralized results was found.

LIMITATIONS

The considered studies are characterized by substantial methodological heterogeneity in terms of the patients' medication status and washout period, explored cerebral regions, and neuropsychological tasks.

CONCLUSIONS

fNIRS seems to be a promising tool for the detection of pharmacological-treatment biomarkers in samples of children and adolescents with ADHD.

Prefrontal Contributions to Attention and Working Memory

The processes of attention and working memory are conspicuously interlinked, suggesting that they may involve overlapping neural mechanisms. Working memory (WM) is the ability to maintain information in the absence of sensory input. Attention is the process by which a specific target is selected for further processing, and neural resources directed toward that target. The content of WM can be used to direct attention, and attention can in turn determine which information is encoded into WM. Here we discuss the similarities between attention and WM and the role prefrontal cortex (PFC) plays in each. First, at the theoretical level, we describe how attention and WM can both rely on models based on attractor states. Then we review the evidence for an overlap between the areas involved in both functions, especially the frontal eye field (FEF) portion of the prefrontal cortex. We also discuss similarities between the neural changes in visual areas observed during attention and WM. At the cellular level, we review the literature on the role of prefrontal DA in both attention and WM at the behavioral and neural levels. Finally, we summarize the anatomical evidence for an overlap between prefrontal mechanisms involved in attention and WM. Altogether, a summary of pharmacological, electrophysiological, behavioral, and anatomical evidence for a contribution of the FEF part of prefrontal cortex to attention and WM is provided.

A haplotype of the dopamine transporter gene modulates regional homogeneity, gray matter volume, and visual memory in children with attention-deficit/hyperactivity disorder

BACKGROUND

The dopamine transporter gene (DAT1) and visual memory deficits have been consistently reported to be associated with attention-deficit/hyperactivity disorder (ADHD). This study aimed to examine whether a DAT1 haplotype affected functional and structural brain alterations in children with ADHD and whether those alterations were associated with visual memory.

METHOD

We recruited a total of 37 drug-naïve children with ADHD (17 with the DAT1 rs27048 (C)/rs429699 (T) haplotype and 20 without the CT haplotype) and 37 typically developing children (17 with the CT haplotype and 20 without the CT haplotype). Visual memory was assessed by the pattern recognition memory (PRM) and spatial recognition memory (SRM) tasks. We analyzed functional and structural brain architecture with regional homogeneity (ReHo) and gray matter volume (GMV).

RESULTS

The CT haplotype was associated with decreased ReHo in the left superior occipital gyrus, cuneus, and precuneus; and decreased GMV in the left superior occipital gyrus, cuneus, and precuneus, and in the right angular gyrus. Significant interactions of ADHD and the CT haplotype were found in the right postcentral gyrus for ReHo and in the right supplementary motor area for GMV. For the ADHD-CT group, we found negative correlations of total correct responses in PRM and SRM and positive correlations of mean latency of correct responses in PRM with the GMV in the left superior occipital gyrus, cuneus, and precuneus.

CONCLUSIONS

Our findings suggest that the DAT1-related GMV alterations in the posterior cortical regions may contribute to visual memory performance in children with ADHD.

Prefrontal cortex dysfunction in hypoxic-ischaemic encephalopathy contributes to executive function impairments in rats: Potential contribution for attention-deficit/hyperactivity disorder

OBJECTIVES

The attention-deficit/hyperactivity disorder (ADHD) compromises the quality of life of individuals including adaptation to the social environment. ADHD aetiology includes perinatal conditions such as hypoxic-ischaemic events; preclinical studies have demonstrated attentional deficits and impulsive-hyperactive outcomes after neonatal hypoxic and/or ischaemic intervention, but data are missing to understand this relationship. Thus, the aim of this study was to evaluate executive function (EF) and impulsivity, and tissue integrity and dopaminergic function in the prefrontal cortex (PFC) of rats submitted to hypoxia-ischaemia (HI).

METHODS

At postnatal day (PND) 7, male Wistar rats were divided into control (n = 10) and HI groups (n = 11) and the HI procedure was conducted. At PND60, the animals were tested in the attentional set-shifting (ASS) task to EF and in the tolerance to delay of reward for assessment of impulsivity. After, morphological analysis and the dopaminergic system were evaluated in the PFC.

RESULTS

Animals subjected to HI had impairments in EF evidenced by a behavioural inflexibility that was correlated to PFC atrophy. Moreover, HI animals presented reduced D2 receptors in the ipsilateral side of ischaemia in the PFC.

CONCLUSIONS

Animals submitted to HI presented impaired EF associated with tissue atrophy and dopaminergic disturbance in the PFC.

Amphetamine Modestly Improves Conners' Continuous Performance Test Performance in Healthy Adults

OBJECTIVES

Amphetamine improves vigilance as assessed by continuous performance tests (CPT) in children and adults with attention deficit hyperactivity disorder (ADHD). Less is known, however, regarding amphetamine effects on vigilance in healthy adults. Thus, it remains unclear whether amphetamine produces general enhancement of vigilance or if these effects are constrained to the remediation of deficits in patients with ADHD.

METHODS

We tested 69 healthy adults (35 female) on a standardized CPT (Conner's CPT-2) after receiving 10- or 20-mg d-amphetamine or placebo. To evaluate potential effects on learning, impulsivity, and perseveration, participants were additionally tested on the Iowa Gambling Task (IGT) and Wisconsin Card Sorting Task (WCST).

RESULTS

Participants receiving placebo exhibited the classic vigilance decrement, demonstrated by a significant reduction in attention (D') across the task. This vigilance decrement was not observed, however, after either dose of amphetamine. Consistent with enhanced vigilance, the 20-mg dose also reduced reaction time variability across the task and the ADHD confidence index. The effects of amphetamine appeared to be selective to vigilance since no effects were observed on the IGT, WCST, or response inhibition/perseveration measures from the CPT.

CONCLUSIONS

The present data support the premise that amphetamine improves vigilance irrespective of disease state. Given that amphetamine is a norepinephrine/dopamine transporter inhibitor and releaser, these effects are informative regarding the neurobiological substrates of attentional control. (JINS, 2018, 24, 283-293).

Exploring the Effects of Working Memory on Time Perception in Attention Deficit Hyperactivity Disorder

Children with attention deficit hyperactivity disorder (ADHD) are often reported to have deficits of time perception. However, there is a strong relation between performance on tasks of working memory and time perception. Thus, it is possible that the poor performance of children with ADHD on time perception results from their deficit of working memory. In this study, the working memory of participants was separately assessed; therefore, we could explore the relationship between working memory and time perception of children with ADHD. Fifty-six children with ADHD and those of healthy controls completed tasks measuring working memory and time perception. The results showed that the time discrimination ability of children with ADHD was poorer than that of controls. However, there was a strong association between time perception and working memory. After controlling working memory and intelligence, the time discrimination ability of children with ADHD was not significantly poorer than that of controls. We suggest that there is an interdependent relationship between time perception and working memory for children with ADHD.

Attentional set-shifting and social abilities in children with schizotypal and comorbid autism spectrum disorders

OBJECTIVE

While diagnostically independent, autism and schizotypal disorders can co-occur. Their concurrent impact on outcomes and phenotypes has not been investigated. We investigated the impact of comorbid autism and schizotypal disorders in children on executive functioning and socio-pragmatic skills - core features of both disorders.

METHOD

Executive functioning (assessed with the Cambridge Neuropsychological Test Automated Battery) and socio-pragmatic skills (assessed using the Melbourne Assessment of Schizotypy in Kids) were investigated in a total of 67 (6-12 year old) children with autism ( n = 15; M/F = 10/5), schizotypal disorder ( n = 8; M/F = 5/3) and comorbid autism and schizotypal disorder ( n = 12; M/F = 5/7) and typically developing children ( n = 32; M/F = 17/15).

RESULTS

Both the autism and schizotypal disorder groups performed more poorly than the typically developing group on socio-pragmatic skills and overall performance (i.e. number of stages completed) of the intra-/extra-dimensional set-shifting task (all ps < 0.001). Clear distinctions between the autism and schizotypal groups were present in the intra-/extra-dimensional task relative to the typically developing group - the autism group had difficulties with extra-dimensional shifts ( p < 0.001), and the schizotypal disorder group with intra-dimensional shifts ( p = 0.08). Interestingly, the overall performance of the comorbid group on the intra-/extra-dimensional task was not significantly different from the typically developing group, and they were superior to both the autism ( p = 0.019) and schizotypal disorder ( p = 0.042) groups on socio-pragmatic skills.

CONCLUSION

The phenotypical overlap between autism and schizotypal disorders may be precipitated by different cognitive styles and/or mechanisms associated with attention and information processing. We propose that sustaining and switching attention represent two poles of irregularities across the autism and schizotypal spectra, which appear to converge in a compensatory manner in the comorbid group. Our findings highlight the importance of investigating children with a dual diagnosis of autism and schizotypal disorders, and raise intriguing questions about possible mechanisms to explain the attenuated impairment observed in the group of children with comorbid autism and schizotpyal disorders.

Executive functioning, academic skills, and quality of life in pediatric patients with brain tumors post-proton radiation therapy

Radiation therapy (RT) is integral in the treatment of pediatric brain tumors; however, photon RT (XRT) often results in intellectual decline, executive functioning (EF) deficits, academic underachievement/failure, and lower health-related quality of life (HRQoL). Proton RT (PRT) provides more targeted therapy, minimizing damage to the developing brain, yet few studies have examined its neuropsychological effects. This study investigated the role of EF in academic skills and HRQoL in a sample of children treated with PRT. A mediation model was proposed in which academic skills mediated relations between aspects of EF and school-based HRQoL (sHRQoL). Sixty-five children (x̅_age = 12.4; 43.9% male) treated with PRT completed follow-up neuropsychological testing as part of routine care. Measures included assessment of intellectual functioning, EF, attention, and academic skills (reading, math, spelling). Parents reported on children's EF and attention problems. sHRQoL was assessed via child self-report. Children who underwent PRT demonstrated relatively intact intelligence, academics, attention, EF, and sHRQoL, but were at risk for reduced processing speed. Poorer working memory and processing speed were related to lower sHRQoL. Better EF and faster processing speed were associated with better academic skills, which were linked to higher sHRQoL. Better working memory was associated with better math performance, which was linked to higher sHRQoL; this relationship did not hold for reading or spelling. Results highlight the importance of EF skills in academic performance and sHRQoL, and the need for routine screening of EF deficits and proactive supports. Supports may include cognitive rehabilitation and in-class accommodations. Overall, results compare favorably to XRT outcomes reported in the literature.

Cognitive performance of juvenile monkeys after chronic fluoxetine treatment

Potential long term effects on brain development are a concern when drugs are used to treat depression and anxiety in childhood. In this study, male juvenile rhesus monkeys (three-four years of age) were dosed with fluoxetine or vehicle (N=16/group) for two years. Histomorphometric examination of cortical dendritic spines conducted after euthanasia at one year postdosing (N=8/group) suggested a trend toward greater dendritic spine synapse density in prefrontal cortex of the fluoxetine-treated monkeys. During dosing, subjects were trained for automated cognitive testing, and evaluated with a test of sustained attention. After dosing was discontinued, sustained attention, recognition memory and cognitive flexibility were evaluated. Sustained attention was affected by fluoxetine, both during and after dosing, as indexed by omission errors. Response accuracy was not affected by fluoxetine in post-dosing recognition memory and cognitive flexibility tests, but formerly fluoxetine-treated monkeys compared to vehicle controls had more missed trial initiations and choices during testing. Drug treatment also interacted with genetic and environmental variables: MAOA genotype (high- and low transcription rate polymorphisms) and testing location (upper or lower tier of cages). Altered development of top-down cortical regulation of effortful attention may be relevant to this pattern of cognitive test performance after juvenile fluoxetine treatment.

A dimensional approach to modeling symptoms of neuropsychiatric disorders in the marmoset monkey

Some patients suffering from the same neuropsychiatric disorder may have no overlapping symptoms whilst others may share symptoms common to other distinct disorders. Therefore, the Research Domain Criteria initiative recognises the need for better characterisation of the individual symptoms on which to focus symptom-based treatment strategies. Many of the disorders involve dysfunction within the prefrontal cortex (PFC) and so the marmoset, due to their highly developed PFC and small size, is an ideal species for studying the neurobiological basis of the behavioural dimensions that underlie these symptoms.Here we focus on a battery of tests that address dysfunction spanning the cognitive (cognitive inflexibility and working memory), negative valence (fear generalisation and negative bias) and positive valence (anhedonia) systems pertinent for understanding disorders such as ADHD, Schizophrenia, Anxiety, Depression and OCD. Parsing the separable prefrontal and striatal circuits and identifying the selective neurochemical modulation (serotonin vs dopamine) that underlie cognitive dysfunction have revealed counterparts in the clinical domain. Aspects of the negative valence system have been explored both at individual- (trait anxiety and genetic variation in serotonin transporter) and circuit-based levels enabling the understanding of generalisation processes, negative biases and differential responsiveness to SSRIs. Within the positive valence system, the combination of cardiovascular and behavioural measures provides a framework for understanding motivational, anticipatory and consummatory aspects of anhedonia and their neurobiological mechanisms. Together, the direct comparison of experimental findings in marmosets with clinical studies is proving an excellent translational model to address the behavioural dimensions and neurobiology of neuropsychiatric symptoms. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 328-353, 2017.

Memantine in the Treatment of Executive Function Deficits in Adults With ADHD

OBJECTIVE

To evaluate the efficacy and safety of memantine hydrochloride as an adjunct to stimulant pharmacotherapy for treating executive function deficits (EFDs) in adults with ADHD.

METHOD

This was a 12-week, double-blind, placebo-controlled, randomized clinical trial of memantine added to open-label treatment with stimulant medication. Because of the small sample size, we considered a standardized mean difference (equivalent to effect size) of ≥0.5 and odds ratios ≥2 as indicators of trend improvements.

RESULTS

Twelve participants received memantine and 14 received a placebo. Trend improvements favoring memantine were observed on Behavior Rating Inventory of Executive Functions-Adult Inhibition and Self-Monitor subscales when compared with Placebo. No significant changes were noted on the Cambridge Neuropsychological Test Automated Battery.

CONCLUSION

Among adults with ADHD and EFDs, adjunct treatment with memantine to osmotic release oral system-methylphenidate (OROS-MPH) was associated with improvements in selective areas of executive functioning, supporting the need for further research.

The relationship between nonmedical use of prescription stimulants, executive functioning and academic outcomes

The nonmedical use of prescription stimulants (NMUPS) is a prevalent issue among college students. The primary reason college students report NMUPS is for academic enhancement i.e., to perform better on schoolwork/tests and focus better in class. Executive functioning (EF), which includes abilities that allow for planning, cognitive flexibility, self-regulation, and goal-directed behavior, are potential mechanisms underlying academic performance. Preliminary research has revealed that college students with EF deficits are more likely to have educational difficulties and take part in risky behavior. Based on the literature, it is possible that students with EF deficits are engaging in NMUPS to help them overcome these deficits to succeed academically. Therefore, the purpose of the present study was to examine the relationship between NMUPS and EF among a sample of college students. The sample included 308 students from six public universities located in various regions of the United States. Measures used in this study were the SSQ, BDEFS and GPA. Results revealed 18.8% of the general sample reported NMUPS. Participants with clinically significant EF deficits reported significantly higher rates of NMUPS, compared to those without deficits in EF. NMUPS, however, did not moderate the relationship between EF and GPA. The present findings have implications for identifying sub-populations of college students who might be at risk for engaging in NMUPS and to improve prevention and intervention strategies aimed at reducing NMUPS. Limitations and suggestions for future research are discussed.

Executive function deficits associated with current and past major depressive symptoms

BACKGROUND

Although there has been extensive research showing that depression is associated with executive function (EF) deficits, the nature of these deficits is not clearly delineated. Specifically, previous reviews on this topic have yielded different conclusions about the particular domains of EF that are disrupted in depressed individuals. Further, research on whether these deficits persist after depressed mood has remitted is less prevalent and not consistent.

METHODS

In two independent samples of college students, we examined associations between clinical ratings of current and past symptoms of a Major Depressive Episode (MDE) and difficulties in two domains of EF: inhibition and shifting. In Study 1 (n=162), EF was measured using behavioral tasks shown to index these two domains. In Study 2 (n=95), EF was measured using a self-report questionnaire believed to capture EF difficulties experienced in daily life.

RESULTS

In both studies, past MDE symptoms were associated with worse shifting. In contrast, current MDE symptoms were associated with worse inhibition, though only on the behavioral measure (in Study 1).

LIMITATIONS

Both studies used college samples and retrospective assessments of past symptoms. Further, only two domains of EF were examined, and the EF measures employed in each study have their own unique methodological limitations.

CONCLUSIONS

Findings suggest that inhibition deficits vary as a function of current symptoms and thus may be a by-product of distress rather than a causal contributor. In contrast, shifting deficits associated with depression appear to be more enduring, suggesting that they could contribute to risk for depression.

Cognitive Translation Using the Rodent Touchscreen Testing Approach

The development of novel therapeutic avenues for the treatment of cognitive deficits in psychiatric and neurodegenerative disease is of high importance, yet progress in this field has been slow. One reason for this lack of success may lie in discrepancies between how cognitive functions are assessed in experimental animals and humans. In an attempt to bridge this translational gap, the rodent touchscreen testing platform is suggested as a translational tool. Specific examples of successful cross-species translation are discussed focusing on paired associate learning (PAL), the 5-choice serial reaction time task (5-CSRTT), the rodent continuous performance task (rCPT) and reversal learning. With ongoing research assessing the neurocognitive validity of tasks, the touchscreen approach is likely to become increasingly prevalent in translational cognitive research.

Antisaccade-related brain activation in children with attention-deficit/hyperactivity disorder--A pilot study

While antisaccade paradigms invoke circuitry associated with cognitive control and attention-deficit/hyperactivity disorder (ADHD), there is a dearth of functional magnetic resonance imaging (fMRI) investigations using antisaccade tasks among children with ADHD. Neural correlates associated with antisaccade performance were examined with fMRI in 11 children with ADHD (10 medicated) matched to 11 typically developing children. Significantly greater brain activation in regions in right dorsolateral prefrontal cortex and caudate nucleus was observed in children with ADHD relative to the control group. This pattern separated the children into their respective groups in a taxonomic manner. Sensitivity analyses probing comorbidity and medication-specific effects showed that results were consistent; however, the caudate nucleus difference was only detectable in the full sample, or in subsets with a more relaxed cluster threshold. Antisaccade performance did not significantly differ between the groups, perhaps as a result of greater brain activation or medication effects in the ADHD group. Thus, antisaccade paradigms may have sensitivity and specificity for the investigation of cognitive control deficits and associated neural correlates in ADHD, and may contribute towards the development of new treatment approaches for children with the disorder.

Obesity, Physical Activity, and Sedentary Behavior of Youth With Learning Disabilities and ADHD

Obesity, physical activity, and sedentary behavior in childhood are important indicators of present and future health and are associated with school-related outcomes such as academic achievement, behavior, peer relationships, and self-esteem. Using logistic regression models that controlled for gender, age, ethnicity/race, and socioeconomic status, we investigated the likelihood that youth with learning disabilities (LD) and attention-deficit/hyperactivity disorder (ADHD) are obese, physically active, and sedentary using a nationally representative sample of 45,897 youth in the United States from 10 to 17 years of age. Results indicated that youth with comorbid LD/ADHD were significantly more likely than peers without LD or ADHD to be obese; that youth with LD only, ADHD only, and comorbid LD/ADHD were significantly less likely to meet recommended levels of physical activity; and that youth with LD only were significantly more likely to exceed recommended levels of sedentary behavior. Medication status mediated outcomes for youth with ADHD. We offer school-based recommendations for improving health-related outcomes for students with LD and ADHD.

Computerized Cognitive Training for Amelioration of Cognitive Late Effects Among Childhood Cancer Survivors: A Randomized Controlled Trial

PURPOSE

Children receiving CNS-directed therapy for cancer are at risk for cognitive problems, with few available empirically supported interventions. Cognitive problems indicate neurodevelopmental disruption that may be modifiable with intervention. This study evaluated short-term efficacy of a computerized cognitive training program and neural correlates of cognitive change.

PATIENT AND METHODS

A total of 68 survivors of childhood acute lymphoblastic leukemia (ALL) or brain tumor (BT) with identified cognitive deficits were randomly assigned to computerized cognitive intervention (male, n = 18; female, n = 16; ALL, n = 23; BT, n = 11; mean age ± standard deviation, 12.21 ± 2.47 years) or waitlist (male, n = 18; female, n = 16; ALL, n = 24; BT, n = 10; median age ± standard deviation, 11.82 ± 2.42 years). Intervention participants were asked to complete 25 training sessions at home with weekly, telephone-based coaching. Cognitive assessments and functional magnetic resonance imaging scans (intervention group) were completed pre- and postintervention, with immediate change in spatial span backward as the primary outcome.

RESULTS

Survivors completing the intervention (n = 30; 88%) demonstrated greater improvement than controls on measures of working memory (mean ± SEM; eg, Wechsler Intelligence Scale for Children [fourth edition; WISC-IV] spatial span backward, 3.13 ± 0.58 v 0.75 ± 0.43; P = .002; effect size [ES], 0.84), attention (eg, WISC-IV spatial span forward, 3.30 ± 0.71 v 1.25 ± 0.39; P = .01; ES, 0.65), and processing speed (eg, Conners' Continuous Performance Test hit reaction time, -2.10 ± 1.47 v 2.54 ± 1.25; P = .02; ES, .61) and showed greater reductions in reported executive dysfunction (eg, Conners' Parent Rating Scale III, -6.73 ± 1.51 v 0.41 ± 1.53; P = .002; ES, 0.84). Functional magnetic resonance imaging revealed significant pre- to post-training reduction in activation of left lateral prefrontal and bilateral medial frontal areas.

CONCLUSION

Study findings show computerized cognitive training is feasible and efficacious for childhood cancer survivors, with evidence for training-related neuroplasticity.

Remission Rate and Functional Outcomes During a 6-Month Treatment With Osmotic-Release Oral-System Methylphenidate in Children With Attention-Deficit/Hyperactivity Disorder

Many definitions have been used to evaluate remission in patients with attention-deficit/hyperactivity disorder (ADHD) in different studies resulting with varied remission rates. This open-label, multicenter study investigated the remission rate in Chinese children (n = 239; aged 6-16 years) with a diagnosis of ADHD (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition), treated with osmotic-release oral-system methylphenidate at doses of 18, 36, and 54 mg, once daily. Two definitions of remission were used: (1) (primary end point): average scores of SNAP-IV (Swanson, Nolan, and Pelham, Fourth Edition) items of 1 or less (0-3 rating scale for each item) according to the subtype of ADHD (inattentive [1-9], hyperactive-impulsive [10-18], and combined type [1-18]), and (2) total score of SNAP-IV items 1 to 18 of 18 or less, at week 8. The study consisted of screening/baseline, titration/open-label treatment (8 weeks), and extended observation (up to 24 weeks) phases. Secondary efficacy assessments were Clinical Global Impression-Improvement (clinical efficacy), Behavior Rating Inventory of Executive Function Scale (BRIEF; executive function behaviors), and Weiss Functional Impairment Rating Scale (social function). Validity of remission was assessed by comparing the function measures (BRIEF and Weiss's) between patients who achieved remission and those who did not. At week 8, 69.3% (151/218) of patients achieved remission by definition 1, and 73.2% (161/220) by definition 2. At weeks 8 and 24, the remission group had significantly lower BRIEF, Weiss's, and Clinical Global Impression-Improvement scores (P < 0.001 for all) compared with the nonremission group. Overall, treatment with osmotic-release oral-system methylphenidate was well tolerated, with increased remission rates in children with ADHD.

The impact of neuroscience on society: cognitive enhancement in neuropsychiatric disorders and in healthy people

In addition to causing distress and disability to the individual, neuropsychiatric disorders are also extremely expensive to society and governments. These disorders are both common and debilitating and impact on cognition, functionality and wellbeing. Cognitive enhancing drugs, such as cholinesterase inhibitors and methylphenidate, are used to treat cognitive dysfunction in Alzheimer's disease and attention deficit hyperactivity disorder, respectively. Other cognitive enhancers include specific computerized cognitive training and devices. An example of a novel form of cognitive enhancement using the technological advancement of a game on an iPad that also acts to increase motivation is presented. Cognitive enhancing drugs, such as methylphenidate and modafinil, which were developed as treatments, are increasingly being used by healthy people. Modafinil not only affects 'cold' cognition, but also improves 'hot' cognition, such as emotion recognition and task-related motivation. The lifestyle use of 'smart drugs' raises both safety concerns as well as ethical issues, including coercion and increasing disparity in society. As a society, we need to consider which forms of cognitive enhancement (e.g. pharmacological, exercise, lifelong learning) are acceptable and for which groups (e.g. military, doctors) under what conditions (e.g. war, shift work) and by what methods we would wish to improve and flourish.

A systematic review of attention deficit hyperactivity disorder (ADHD) and mathematical ability: current findings and future implications

BACKGROUND

Several recent behavioural and behavioural genetic studies have investigated the relationship between attention deficit hyperactivity disorder (ADHD) and mathematical ability. The aim of this systematic review was to provide an overview of these studies to date. An emphasis was placed on reviewing results that explored the association between mathematics and the two ADHD components of attention and hyperactivity-impulsivity separately.

METHODS

A systematic search of quantitative studies investigating the association between mathematics and ADHD was conducted across five databases (PsychINFO, Web of Science, PubMed, EMBASE, and Scopus). A total of 30 cross-sectional and four longitudinal studies were included in this review.

RESULTS

Narrative synthesis of the results was provided using PRISMA guidelines. Taken together, the studies pointed at substantial evidence for a negative association between ADHD symptoms and mathematical ability. This association was particularly marked for the inattentive component of ADHD than for the hyperactive-impulsive component. Evidence from twin studies also showed a significant genetic correlation between mathematics and ADHD, which was greater for the inattentive component of ADHD compared to the hyperactive-impulsive component.

CONCLUSIONS

The differential relationship of the hyperactivity-impulsivity and inattention domains with mathematics emphasises the heterogeneity within the disorder and suggests a partially different aetiology of the two ADHD domains. A better understanding of the aetiology of ADHD could help develop more efficient interventions aimed at the reduction of its symptoms. It could also offer an explanatory framework for shortcomings in achievement and inform the development of non-pharmacological intervention strategies.

[Formula: see text]Differences in memory functioning between children with attention-deficit/hyperactivity disorder and/or focal epilepsy

Prior research has shown that attention-deficit/hyperactivity disorder (ADHD) and epilepsy are frequently comorbid and that both disorders are associated with various attention and memory problems. Nonetheless, limited research has been conducted comparing the two disorders in one sample to determine unique versus shared deficits. Hence, we investigated differences in working memory (WM) and short-term and delayed recall between children with ADHD, focal epilepsy of mixed foci, comorbid ADHD/epilepsy and controls. Participants were compared on the Core subtests and the Picture Locations subtest of the Children's Memory Scale (CMS). Results indicated that children with ADHD displayed intact verbal WM and long-term memory (LTM), as well as intact performance on most aspects of short-term memory (STM). They performed worse than controls on Numbers Forward and Picture Locations, suggesting problems with focused attention and simple span for visual-spatial material. Conversely, children with epilepsy displayed poor focused attention and STM regardless of the modality assessed, which affected encoding into LTM. The only loss over time was found for passages (Stories). WM was intact. Children with comorbid ADHD/epilepsy displayed focused attention and STM/LTM problems consistent with both disorders, having the lowest scores across the four groups. Hence, focused attention and visual-spatial span appear to be affected in both disorders, whereas additional STM/encoding problems are specific to epilepsy. Children with comorbid ADHD/epilepsy have deficits consistent with both disorders, with slight additive effects. This study suggests that attention and memory testing should be a regular part of the evaluation of children with epilepsy and ADHD.

The rat's not for turning: Dissociating the psychological components of cognitive inflexibility

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Non-rewarded or irrelevant prior associations are important for flexible responding.

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Associations of reward and non-reward in reversal learning are neurally dissociable.

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Disruption of prior irrelevant or rewarded associations cause pathological deficits.

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Experimental paradigms of cognitive flexibility can be improved to aid translation.

Executive function is commonly assessed by assays of cognitive flexibility such as reversal learning and attentional set-shifting. Disrupted performance in these assays, apparent in many neuropsychiatric disorders, is frequently interpreted as inability to overcome prior associations with reward.

However, non-rewarded or irrelevant associations may be of considerable importance in both discrimination learning and cognitive flexibility. Non-rewarded associations can have greater influence on choice behaviour than rewarded associations in discrimination learning. Pathology-related deficits in cognitive flexibility can produce selective disruptions to both the processing of irrelevant associations and associations with reward. Genetic and pharmacological animal models demonstrate that modulation of reversal learning may result from alterations in either rewarded or non-rewarded associations.

Successful performance in assays of cognitive flexibility can therefore depend on a combination of rewarded, non-rewarded, and irrelevant associations derived from previous learning, accounting for some inconsistencies observed in the literature. Taking this combination into account may increase the validity of animal models and may also reveal pathology-specific differences in problem solving and executive function.

Fronto-temporal white matter connectivity predicts reversal learning errors

Each day, we make hundreds of decisions. In some instances, these decisions are guided by our innate needs; in other instances they are guided by memory. Probabilistic reversal learning tasks exemplify the close relationship between decision making and memory, as subjects are exposed to repeated pairings of a stimulus choice with a reward or punishment outcome. After stimulus-outcome associations have been learned, the associated reward contingencies are reversed, and participants are not immediately aware of this reversal. Individual differences in the tendency to choose the previously rewarded stimulus reveal differences in the tendency to make poorly considered, inflexible choices. Lesion studies have strongly linked reversal learning performance to the functioning of the orbitofrontal cortex, the hippocampus, and in some instances, the amygdala. Here, we asked whether individual differences in the microstructure of the uncinate fasciculus, a white matter tract that connects anterior and medial temporal lobe regions to the orbitofrontal cortex, predict reversal learning performance. Diffusion tensor imaging and behavioral paradigms were used to examine this relationship in 33 healthy young adults. The results of tractography revealed a significant negative relationship between reversal learning performance and uncinate axial diffusivity, but no such relationship was demonstrated in a control tract, the inferior longitudinal fasciculus. Our findings suggest that the uncinate might serve to integrate associations stored in the anterior and medial temporal lobes with expectations about expected value based on feedback history, computed in the orbitofrontal cortex.