Causal models of attention-deficit/hyperactivity disorder: from common simple deficits to multiple developmental pathways

Attention Deficit Hyperactivity Disorder, Cannabis Use, and the Endocannabinoid System: A Scoping Review

There is emerging evidence that the endocannabinoid system (ECS) plays a significant role in the pathophysiology of many psychiatric disorders, including attention deficit hyperactivity disorder (ADHD). Increasing evidence suggests that a number of neurobiological correlates between endogenous cannabinoid function and cognitive dysfunction are seen in ADHD, making the ECS a possible target for therapeutic interventions. Cannabis use and cannabis use disorder are more prevalent in individuals with ADHD, compared to the general population, and there is growing popular perception that cannabis is therapeutic for ADHD. However, the relationship between cannabis use and ADHD symptomology is poorly understood. Further understanding of the role of the ECS in ADHD pathophysiology and the molecular alterations that may be a target for treatment is needed. To further the science on this emerging area of research, this scoping review describes the preclinical and clinical evidence seeking to understand the relationship between the ECS and ADHD.

Two sides of the same coin? What neural processing of emotion and rewards can tell us about complex post-traumatic stress disorder and borderline personality disorder

BACKGROUND

Borderline personality disorder (BPD) and complex posttraumatic stress disorder (cPTSD) share clinical similarities, complicating diagnosis and treatment. Research on the neurobiology of BPD and monotraumatic PTSD has shown that a prefrontal-limbic imbalance in emotional and reward processing is a hallmark of both disorders, but studies examining this network in cPTSD are lacking. Therefore, this study aimed to directly compare neural processing of emotion and reward during decision making in cPTSD and BPD.

METHODS

Using functional magnetic resonance imaging, we measured neural activity in female patients (27 patients with cPTSD, 21 patients with BPD and 37 healthy controls) during a Desire-Reason Dilemma task featuring distracting fearful facial expressions.

RESULTS

We found no differences in neural activation when comparing cPTSD and BPD. However, when grouping patients based on symptom severity instead on diagnosis, we found that increased symptoms of cPTSD were associated with increased activation of dorsolateral prefrontal cortex during reward rejection, whereas increased symptoms of BPD were associated with decreased activation in prefrontal and limbic regions during reward rejection with distracting negative emotional stimuli.

CONCLUSION

This is the first study to investigate and compare emotional processing and reward-based decision making in cPTSD and BPD. Although we found no neural differences between disorders, we identified symptom-related neural patterns. Specifically, we found that elevated cPTSD symptoms were related to greater sensitivity to reward stimuli, whereas heightened BPD symptoms were related to increased susceptibility to emotional stimuli during goal-directed decision making. These findings enhance our understanding of neural pathomechanisms in trauma-related disorders.

Prevalence and Correlates of Self-Reported ADHD Symptoms in Bariatric Patients: Focus on Mood and Anxiety Comorbidity, Disordered Eating, and Temperamental Traits

PURPOSE

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition characterized by inattention, hyperactivity, and impulsivity. A positive association between ADHD and obesity has been observed, especially in adult samples. In this study, prevalence and correlates of self-reported symptoms indicative of a positive screening for ADHD were examined in patients seeking bariatric treatment.

MATERIAL AND METHODS

The study sample was composed of 260 adult patients with obesity referred for bariatric surgery to the Obesity Center of the Endocrinology Unit in Pisa University Hospital between January 2006 and November 2016 (BMI ≥ 30 kg/m2; mean ± standard deviation = 46.27 ± 7.45 kg/m2). ADHD symptoms were identified using ADHD Symptom Check-List-90-R Screening Scale. Night-eating, binge-eating/purging behaviors, and temperamental and character traits were assessed in a subsample of 95 patients.

RESULTS

Thirty participants had a positive screening for ADHD (11.5%, 95% CI = 7.9-16.1%). Patients with a positive screening showed significantly higher rates of anxiety disorders (40% vs. 16.5%, χ2 = 7.97, p = 0.005) panic disorder (40% vs. 14.3%, χ2 = 10.48, p = 0.001), and a higher severity of psychopathological symptoms and sleep disturbances than those without. In subsample analyses, ADHD symptoms severity was associated with more bulimic behaviors (r = 0.31-0.46), greater harm avoidance (r = 0.45-0.66), less self-directedness (r =  - 0.44-0.63), and cooperativeness (r =  - 0.26-0.42).

CONCLUSION

ADHD symptoms may be common in patients with obesity seeking bariatric treatment and are positively associated with disordered eating, internalizing features, and maladaptive character traits.

LEVEL OF EVIDENCE

V, cross sectional descriptive study.

New Advances in Attention-Deficit/Hyperactivity Disorder-like Dogs

Similar to humans, dogs could suffer an Attention-Deficit/Hyperactivity Disorder-like syndrome (ADHD-like). In fact, several studies highlight the use of dogs as a model for studying ADHD. This condition entails behavioral problems expressed through impulsivity, attention issues, hyperactivity, and/or aggression, compromising the quality of life for both the caregiver and the dog. The pathophysiology of ADHD-like is complex and is associated with dysregulation of various neurotransmitters such as serotonin and dopamine. The expression of ADHD-like behavior in dogs would appear to depend on a classical gene-environment interaction as is the case with many neurological disorders in humans. In addition to the described symptomatology, ADHD-like dogs can exhibit strong comorbidities with compulsive behaviors, aggressiveness, inappropriate elimination and fearfulness, in addition to epilepsy, foreign body ingestion, and pruritus. In spite of the fact that there is no veterinary consensus about the diagnosis of ADHD-like, some validated questionnaires could be helpful, but these cannot be used as a unique diagnostic tool. The use of drugs, such as fluoxetine, in addition to an adequate environmental enrichment, relaxation protocols, and behavior modification can achieve an adequate quality of life for both the dog and caregivers.

Alpha event-related decreases during encoding in adults with ADHD - An investigation of sustained attention and working memory processes

BACKGROUND

Executive functioning deficits are central to established neuropsychological models of ADHD. Oscillatory activity, particularly the alpha rhythm (8-12 Hz) has been associated with cognitive impairments in ADHD. However, most studies to date examined such neural mechanisms underlying executive dysfunction in children and adolescents with ADHD, raising the question of whether and to what extent those ADHD-related working memory impairments are still present in adults. To this end, the current study aimed to investigate the role of alpha event-related decreases (ERD) during working memory processes in adults with and without ADHD.

METHODS

We collected electroencephalographic (EEG) data from 85 adults with a lifetime diagnosis of ADHD and 105 controls (aged 32-64), while they performed a continuous performance (CPT) and a spatial delayed response working memory task (SDRT). Time-frequency and independent component analysis (ICA) was used to identify alpha (8-12 Hz) clusters to examine group and condition effects during the temporal profile of sustained attention and working memory processes (encoding, maintenance, retrieval), loads (low and high) and trial type (go and nogo).

RESULTS

Individuals with ADHD exhibited higher reaction time-variability in SDRT, and slower response times in SDRT and CPT, despite no differences in task accuracy. Although working memory load was associated with stronger alpha ERD in both tasks and both groups (ADHD, controls), we found no consistent evidence for attenuated alpha ERD in adults with ADHD, failing to replicate effects reported in children. In contrast, when looking at the whole sample, the correlations of alpha power during encoding with inattention and hyperactivity-impulsivity symptoms were significant, replicating prior findings in children with ADHD, but suggesting an alternate source for these effects in adults.

CONCLUSIONS

Our results corroborate the robustness of alpha as a marker of visual attention and suggest that occipital alpha ERD normalizes in adulthood, but with unique contributions of centro-occipital alpha ERD, suggesting a secondary source. This implies that deviations in processes other than previously reported visuospatial cortex engagement may account for the persistent symptoms and cognitive deficits in adults with a history of ADHD.

Attention-deficit/hyperactivity disorder (ADHD) in cultural context II: a comparison of the links between ADHD symptoms and waiting-related responses in Hong Kong and UK

The concept of attention-deficit/hyperactivity disorder (ADHD) is considered to have cross-cultural validity, but direct comparisons of its psychological characteristics across cultures are limited. This study investigates whether preschool children's ADHD symptoms expressed in two cultures with different views about child behaviour and parenting, Hong Kong and the UK, show the same pattern of associations with their waiting-related abilities and reactions, an important marker of early self-regulation. A community sample of 112 preschoolers (mean age = 46.22 months; 55 from UK, 57 from HK) completed three tasks measuring different waiting elements - waiting for rewards, choosing the amount of time to wait, and having to wait unexpectedly when a task is interrupted. Participants' waiting-related behavioural and emotional reactions were coded. Parents rated their children's ADHD symptoms and delay aversion. Our findings revealed that the associations between ADHD symptoms and waiting-related responses were comparable in both UK and HK samples. This suggests that the core psychological characteristics of ADHD, particularly in relation to waiting behaviours, may exhibit similarity across cultural contexts. Future research can extend this cross-cultural analysis to other ADHD-related psychological domains and explore additional cultural settings.

Effects of Practicing Closed- vs. Open-Skill Exercises on Executive Functions in Individuals with Attention Deficit Hyperactivity Disorder (ADHD)-A Meta-Analysis and Systematic Review

(1) Background: Previous studies have identified discrepancies in improvements in executive functioning in typically developing children when comparing closed- and open-skill exercise interventions. However, there is limited research on executive functioning in attention deficit hyperactivity disorder (ADHD). This study aims to conduct a systematic review and meta-analysis to explore the impact of closed- and open-skill exercises on ADHD populations. (2) Methods: The PRISMA guidelines for systematic reviews were followed to search seven databases to evaluate and analyze studies published from 2013 to 2023. Prospero: CRD42023460452. (3) Results: A meta-analysis of 578 subjects with ADHD in 11 RCTs (Randomized control trial) and 3 NRS (Non-randomized studies) revealed that closed-skill exercise significantly improved executive function subdomains, including inhibitory control (standardized mean differences (SMD) = -1.00), cognitive flexibility (SMD = -1.33), and working memory (SMD = -0.85). Furthermore, open-skill exercise was found to have a positive effect on inhibitory control (SMD = -1.98) and cognitive flexibility (SMD = -0.97) in ADHD patients. Both types of exercise interventions demonstrated an improvement in executive function compared to controls, with open-skill exercises exhibiting superior effects (Qb = 6.26). (4) Conclusions: The review recommends a 12-week intervention cycle with exercise at least twice a week of moderate or higher intensity as suitable for ADHD individuals. This review also encourages individuals with ADHD to engage in exercises involving multiple motor skill types.

Examining the Use of VR as a Study Aid for University Students with ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition characterized by patterns of inattention and impulsivity, which lead to difficulties maintaining concentration and motivation while completing academic tasks. University settings, characterized by a high student-to-staff ratio, make treatments relying on human monitoring challenging. One potential replacement is Virtual Reality (VR) technology, which has shown potential to enhance learning outcomes and promote flow experience. In this study, we investigate the usage of VR with 27 university students with ADHD in an effort to improve their performance in ctableompleting homework, including an exploration of automated feedback via a technology probe. Quantitative results show significant increases in concentration, motivation, and effort levels during these VR sessions and qualitative data offers insight into considerations like comfort and deployment. Together, the results suggest that VR can be a valuable tool in leveling the playing field for university students with ADHD.

Comparing Executive Functions in Children and Adolescents with Autism and ADHD-A Systematic Review and Meta-Analysis

Two neurodevelopmental conditions, autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), have been associated with executive function (EF) impairments but the specificity of their impairments is still controversial. The present meta-analysis aimed to identify the differences in EF profiles of ASD, ADHD, and ASD+ADHD in relation to a control group of individuals with typical development (TD) and to understand whether the EF performance could change depending upon the type of measure used to assess EF (performance tests vs. questionnaires). Results from 36 eligible studies revealed that ADHD and ASD showed more difficulties than the TD group in tests and, particularly, in questionnaires. No significant differences in the EF profile emerged between ASD and ADHD when assessed through neuropsychological tests (d = 0.02), while significant differences emerged when assessed through questionnaires, with ADHD having higher ratings than ASD (d = -0.34). EF questionnaires and neuropsychological tests may catch two different constructs of EF, with the former being more predictive of everyday life EF impairments. The comparison between the double diagnosis group (ADHD+ASD) and the clinical groups pointed out that the former has a more similar EF profile to the ADHD-alone one and that it shows more difficulties than ASD-alone.

Psychometric properties of the Chinese version of the Quick Delay Questionnaire (C-QDQ) and ecological characteristics of reward-delay impulsivity of adults with ADHD

BACKGROUND

The Quick Delay Questionnaire (QDQ) is a short questionnaire designed to assess delay-related difficulties in adults. This study aimed to examine the reliability and validity of the Chinese version of the QDQ (C-QDQ) in Chinese adults, and explore the ecological characteristics of delay-related impulsivity in Chinese adults with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Data was collected from 302 adults, including ADHD (n = 209) and healthy controls (HCs) (n = 93). All participants completed the C-QDQ. The convergent validity, internal consistency, retest reliability and confirmatory factor analysis (CFA) of the C-QDQ were analyzed. The correlations between C-QDQ and two laboratory measures of delay-related difficulties and Barratt Impulsiveness Scale-11 (BIS-11), the comparison of C-QDQ scores between ADHD subgroups and HCs were also analyzed.

RESULTS

The Cronbach's α of C-QDQ was between 0.83 and 0.89. The intraclass correlation coefficient of C-QDQ was between 0.80 and 0.83. The results of CFA of C-QDQ favoured the original two-factor model (delay aversion and delay discounting). Significant positive associations were found between C-QDQ scores and BIS-11 total score and performance on the laboratory measure of delay-related difficulties. Participants with ADHD had higher C-QDQ scores than HCs, and female ADHD reported higher scores on delay discounting subscale than male. ADHD-combined type (ADHD-C) reported higher scores on delay aversion subscale than ADHD-inattention type (ADHD-I).

CONCLUSION

The C-QDQ is a valid and reliable tool to measure delay-related responses that appears to have clinical utility. It can present the delay-related impulsivity of patients with ADHD. Compared to HCs, the level of reward-delay impulsivity was higher in ADHD.

Cumulative Effects of Resting-State Connectivity Across All Brain Networks Significantly Correlate with Attention-Deficit Hyperactivity Disorder Symptoms

Identification of replicable neuroimaging correlates of attention-deficit hyperactivity disorder (ADHD) has been hindered by small sample sizes, small effects, and heterogeneity of methods. Given evidence that ADHD is associated with alterations in widely distributed brain networks and the small effects of individual brain features, a whole-brain perspective focusing on cumulative effects is warranted. The use of large, multisite samples is crucial for improving reproducibility and clinical utility of brain-wide MRI association studies. To address this, a polyneuro risk score (PNRS) representing cumulative, brain-wide, ADHD-associated resting-state functional connectivity was constructed and validated using data from the Adolescent Brain Cognitive Development (ABCD, N = 5,543, 51.5% female) study, and was further tested in the independent Oregon-ADHD-1000 case-control cohort (N = 553, 37.4% female). The ADHD PNRS was significantly associated with ADHD symptoms in both cohorts after accounting for relevant covariates (p < 0.001). The most predictive PNRS involved all brain networks, though the strongest effects were concentrated among the default mode and cingulo-opercular networks. In the longitudinal Oregon-ADHD-1000, non-ADHD youth had significantly lower PNRS (Cohen's d = -0.318, robust p = 5.5 × 10-4) than those with persistent ADHD (age 7-19). The PNRS, however, did not mediate polygenic risk for ADHD. Brain-wide connectivity was robustly associated with ADHD symptoms in two independent cohorts, providing further evidence of widespread dysconnectivity in ADHD. Evaluation in enriched samples demonstrates the promise of the PNRS approach for improving reproducibility in neuroimaging studies and unraveling the complex relationships between brain connectivity and behavioral disorders.

Relationship between delay discounting, delay aversion and psychosocial domains of diabetes care

PURPOSE

Delay discounting and aversion are important areas for diabetes management; however, little has been done to understand the relationship with psychosocial outcomes among adults with type 2 diabetes.

METHODS

This study used data from 365 adults with type 2 diabetes to evaluate relationships between delay discounting and aversion and psychosocial outcomes. Delay discounting and aversion were measured with the validated Quick Delay Questionnaire. Psychosocial outcomes included depression, measured by the PHQ, anxiety by the GAD scale, perceived stress by the PSS, and social support by the Duke Social Support and Stress Scale. Multiple linear regression was used to assess the relationship between delay discounting and aversion on psychological health and social support controlling for relevant covariates.

RESULTS

Mean age of the sample was 61.8 years, 54.5 % were NHB, 41.8 % NHW, and 3.7 % Hispanic/Other. After adjusting for covariates, delay aversion was significantly associated with depression (beta = 0.35; p < 0.001), anxiety (beta = 0.52; p < 0.001), perceived stress (beta = 0.22; p < 0.001), and lower family support (beta = -0.62; p < 0.05). Delay discounting was significantly associated with depression (beta = 0.32; p < 0.001), anxiety (beta = 0.46; p < 0.001), and perceived stress (beta = 0.26; p < 0.001).

LIMITATIONS

This data is cross-sectional, future work should examine the longitudinal relationship while also including additional psychosocial outcomes.

CONCLUSIONS

Delay discounting and aversion are significantly associated with poor psychosocial outcomes, including lower social support. As the body of evidence grows, additional research is needed to better understand the construct, mechanisms, and the impact of choice settings to better inform intervention development.

Vocal emotion recognition in attention-deficit hyperactivity disorder: a meta-analysis

There is debate within the literature as to whether emotion dysregulation (ED) in Attention-Deficit Hyperactivity Disorder (ADHD) reflects deviant attentional mechanisms or atypical perceptual emotion processing. Previous reviews have reliably examined the nature of facial, but not vocal, emotion recognition accuracy in ADHD. The present meta-analysis quantified vocal emotion recognition (VER) accuracy scores in ADHD and controls using robust variance estimation, gathered from 21 published and unpublished papers. Additional moderator analyses were carried out to determine whether the nature of VER accuracy in ADHD varied depending on emotion type. Findings revealed a medium effect size for the presence of VER deficits in ADHD, and moderator analyses showed VER accuracy in ADHD did not differ due to emotion type. These results support the theories which implicate the role of attentional mechanisms in driving VER deficits in ADHD. However, there is insufficient data within the behavioural VER literature to support the presence of emotion processing atypicalities in ADHD. Future neuro-imaging research could explore the interaction between attention and emotion processing in ADHD, taking into consideration ADHD subtypes and comorbidities.

Neural activation, cognitive control, and attention deficit hyperactivity disorder: Evaluating three competing etiological models

BACKGROUND

Cognitive control impairments are observed across several psychiatric conditions, highlighting their role as a transdiagnostic marker. Individuals with attention deficit hyperactivity disorder (ADHD) have difficulties with inhibition, working memory, processing speed, and attention regulation. These cognitive control impairments may either mediate or moderate the association between neurobiological vulnerabilities and phenotypic presentation in neurodevelopmental disorders. Alternately, neurocognitive vulnerabilities in ADHD may be additive, akin to a multiple deficit model. We tested the mediation, moderation, and additive models using neurocognitive data in youth with ADHD.

METHODS

7-11 year-old children diagnosed with ADHD (n = 75) and control children (n = 29) completed EEG recordings and neuropsychological testing (full scale IQ; cognitive control). Caregivers provided ADHD symptom ratings. Correlations and linear regression analyses were completed to examine the associations among cortical functioning (aperiodic slope), cognitive control, and ADHD symptoms.

RESULTS

We found support for an additive model wherein vulnerabilities in aperiodic slope, event-related potentials, and cognitive control each explained unique variance in ADHD symptoms. There was some evidence that cognitive control moderates the effect of atypical cortical development on ADHD symptoms. There was no support for the mediation model.

CONCLUSIONS

The etiology of ADHD symptoms is multifaceted and involves multiple "hits" across neurological and cognitive-behavioral factors.

Remote neurocognitive interventions for attention-deficit/hyperactivity disorder - Opportunities and challenges

Improving neurocognitive functions through remote interventions has been a promising approach to developing new treatments for attention-deficit/hyperactivity disorder (AD/HD). Remote neurocognitive interventions may address the shortcomings of the current prevailing pharmacological therapies for AD/HD, e.g., side effects and access barriers. Here we review the current options for remote neurocognitive interventions to reduce AD/HD symptoms, including cognitive training, EEG neurofeedback training, transcranial electrical stimulation, and external cranial nerve stimulation. We begin with an overview of the neurocognitive deficits in AD/HD to identify the targets for developing interventions. The role of neuroplasticity in each intervention is then highlighted due to its essential role in facilitating neuropsychological adaptations. Following this, each intervention type is discussed in terms of the critical details of the intervention protocols, the role of neuroplasticity, and the available evidence. Finally, we offer suggestions for future directions in terms of optimizing the existing intervention protocols and developing novel protocols.

The right inferior frontal gyrus as pivotal node and effective regulator of the basal ganglia-thalamocortical response inhibition circuit

Background

The involvement of specific basal ganglia-thalamocortical circuits in response inhibition has been extensively mapped in animal models. However, the pivotal nodes and directed causal regulation within this inhibitory circuit in humans remains controversial.

Objective

The main aim of the present study was to determine the causal information flow and critical nodes in the basal ganglia-thalamocortical inhibitory circuits and also to examine whether these are modulated by biological factors (i.e. sex) and behavioral performance.

Methods

Here, we capitalize on the recent progress in robust and biologically plausible directed causal modeling (DCM-PEB) and a large response inhibition dataset (n = 250) acquired with concomitant functional magnetic resonance imaging to determine key nodes, their causal regulation and modulation via biological variables (sex) and inhibitory performance in the inhibitory circuit encompassing the right inferior frontal gyrus (rIFG), caudate nucleus (rCau), globus pallidum (rGP), and thalamus (rThal).

Results

The entire neural circuit exhibited high intrinsic connectivity and response inhibition critically increased causal projections from the rIFG to both rCau and rThal. Direct comparison further demonstrated that response inhibition induced an increasing rIFG inflow and increased the causal regulation of this region over the rCau and rThal. In addition, sex and performance influenced the functional architecture of the regulatory circuits such that women displayed increased rThal self-inhibition and decreased rThal to GP modulation, while better inhibitory performance was associated with stronger rThal to rIFG communication. Furthermore, control analyses did not reveal a similar key communication in a left lateralized model.

Conclusions

Together, these findings indicate a pivotal role of the rIFG as input and causal regulator of subcortical response inhibition nodes.

Effects of others' gaze and facial expression on an observer's microsaccades and their association with ADHD tendencies

BACKGROUND

The aim of this study was to examine the effect of others' gaze on an observer's microsaccades. We also aimed to conduct preliminary investigations on the relationship between the microsaccadic response to a gaze and a gazer's facial expression and attention-deficit/hyperactivity disorder (ADHD) tendencies.

METHODS

Twenty healthy undergraduate and graduate students performed a peripheral target detection task by using unpredictable gaze cues. During the task, the participants' eye movements, along with changes in pupil size and response times for target detection, were recorded. ADHD tendencies were determined using an ADHD questionnaire.

RESULTS

We found that consciously perceiving the gaze of another person induced the observer's attention; moreover, microsaccades were biased in the direction opposite to the gaze. Furthermore, these microsaccade biases were differentially modulated, based on the cognitive processing of the facial expressions of the gaze. Exploratory correlation analysis indicated that microsaccade biases toward gazes with fearful expressions may specifically be correlated with participant characteristics, including inattention.

CONCLUSIONS

Our findings support that microsaccades reflect spatial attention processing and social cognitive processing. Moreover, the exploratory correlation analysis results suggested the potential benefit of using microsaccade bias toward spatial attention to assess pathophysiological responses associated with ADHD tendencies.

Impulsive choice in individuals with comorbid amphetamine use disorder and attention deficit-hyperactivity disorder

BACKGROUND

Amphetamine use disorder (AMPH) and attention deficit-hyperactivity disorder (ADHD) often co-occur and are associated with poor treatment outcomes. Elevated impulsivity is a core feature in both disorders. Little is known however about the specific neurocognitive profile regarding different facets of impulsivity, and specifically impulsive choice, in comorbid populations.

METHODS

Three groups (ADHD + AMPH, ADHD only and healthy controls (HC)) were assessed with self-reported impulsivity and cognitive tasks of impulsive choice, operationalized as delay aversion (DA) and reflection impulsivity.

RESULTS

Twenty-nine participants with comorbid ADHD + AMPH, 25 participants with ADHD only and 116 HC completed screening, including self-rating scales, and cognitive testing. 20, 16 and 114 participants completed computerized cognitive tasks in the ADHD + AMPH group, ADHD group and HC group, respectively. The ADHD + AMPH group reported significantly higher motor, attentional and non-planning impulsiveness, and showed a significantly higher degree of impulsive choice, compared to both groups. There were no differences in task-related impulsiveness between ADHD only and HC.

CONCLUSIONS

The current findings suggest that individuals with ADHD + AMPH have overall elevated levels of impulsivity compared to individuals with ADHD only. In addition, that ADHD + AMPH is specifically associated with impairments in task-related impulsive choice, which was not found in ADHD only compared to HC. The neurocognitive profile in this specific patient group may represent a need for more systematic screening within healthcare settings in order to develop effective and targeted treatment for comorbid patients.

TRIAL REGISTRATION

EudraCT, 2012-004298-20.

Sex differences in conduct and emotional outcomes for young people with hyperactive/inattentive traits and social communication difficulties between 9 and 16 years of age: a growth curve analysis

BACKGROUND

The purpose of this paper is to identify the trajectory of conduct and emotional problems for young people within the general population at four time points (between 9 years 7 months and 16 years 6 months), investigate their relationship with hyperactive/inattentive traits and explore the moderating effect of autistic social traits (ASTs).

METHODS

Data from 9305 individuals involved in The Avon Longitudinal Study of Parents and Children (ALSPAC) study were included. Conduct and emotional problems and hyperactive/inattentive traits were measured by the Strengths and Difficulties Questionnaire. ASTs were assessed using the Social Communication Disorder Checklist. Individual trajectories for conduct and emotional problems were identified via growth curve modelling. Hyperactive/inattentive traits were included within the growth curve model as a time-varying covariate to determine their effect on these outcomes. Finally, participants were split into two groups (below and above clinical threshold ASTs Groups) and multi-group invariance testing was conducted on the data to identify the moderating effect of ASTs on the relationship between hyperactive/inattentive traits and outcomes (i.e. conduct and emotional problems).

RESULTS

Hyperactive/inattentive traits were associated with higher rates of conduct and emotional problems for both boys and girls. The presence of ASTs moderated these relationships for boys, but not for girls, by increasing the risk of boys with hyperactive/inattentive traits developing greater conduct and emotional problems.

CONCLUSIONS

These findings underscore the importance of identifying hyperactive/inattentive traits and ASTs in young people and addressing the increased risk of conduct and emotional problems. Research and clinical implications are explored.

Do Language-Related Cognitive Capacities Help Predict Adjustment in Children with Attention-Deficit/Hyperactivity Disorder?

The goal of this paper was to examine the role that language-related cognitive capacities (LRCC) might play in explaining adjustment of 7 to 12 year-old children (M_age = 9.24; SD_age = 0.91) with and without ADHD. The sample was comprised of 178 children with ADHD and 86 typically-developing children (77.3% male; 81.4% White; 9.5% Black; 1.9% Hispanic; 0.8% Asian; 5.7% multiracial; 0.8% did not report race/ethnicity). Using simultaneous regression, we examined whether LRCC accounted for unique variance in achievement, attention problems, oppositional problems, conduct problems, and internalizing, over and above what standard covariates and ADHD diagnostic status could explain. Finally, we examined LRCC as a mediator of the relation between ADHD diagnostic status and these adjustment measures. Results indicated that LRCC significantly predicted 6 of 7 and partially mediated 5 of 7 measures, suggesting that language-related constructs warrant greater attention in diagnosis and treatment of ADHD.

Treatment Modalities for Internet Addiction in Children and Adolescents: A Systematic Review of Randomized Controlled Trials (RCTs)

BACKGROUND

In recent years, the use of the internet among children and adolescents has dramatically increased, leading to growing concerns regarding the potential risks of excessive internet use and addiction. Addressing these concerns, this systematic review aims to summarize current evidence on the effectiveness of treatment interventions for internet addiction among children and adolescents.

METHOD

We performed a systematic review using PubMed, Web of Science, PsycInfo, and Google Scholar with search terms including "internet addiction", "problematic internet use", "children" or "adolescents", "treatment" and "randomized controlled trial". We found 10 Randomized Controlled Trials (RCTs) meeting the criteria and included them in this systematic review.

RESULTS

This systematic review analyzed 10 randomized controlled trials focused on treatment interventions for internet addiction in adolescents and young adults. The interventions used were diverse, including cognitive-behavioral therapy (CBT), medication, electro-acupuncture (EA), and solution-focused approaches. The measures used to assess the effectiveness of the interventions also varied, but most studies reported moderate to large effect sizes for at least some outcomes. Overall, the studies suggest that interventions such as CBT and EA can be effective in reducing symptoms of internet addiction, internet gaming disorder, and unspecified internet use disorders. School-based programs and brief manualized CBT programs also show promise, though more research is needed to determine their long-term effectiveness.

CONCLUSION

Promising treatment approaches for internet addiction are emerging, but inconsistencies in conceptualization, language, and diagnostic criteria present some challenges. The growing recognition of problematic internet use, as shown by the DSM-5's recognition of Internet Gaming Disorder, highlights the need for a multidisciplinary approach and standardized criteria to facilitate accurate reporting across studies. Continued research is needed to identify effective treatments and diagnostic criteria for internet addiction, with the potential to offer practical insights into effective medications and therapies.

Conditioned approach behavior of SHR and SD rats during Pavlovian conditioning

Individual differences in reward-related learning are relevant to many behavioral disorders. Sensory cues that predict reward can become incentive stimuli that adaptively support behavior, or alternatively, cause maladaptive behaviors. The spontaneously hypertensive rat (SHR) expresses a genetically determined elevated sensitivity to delay of reward, and has been extensively studied as a behavioral model for attention deficit hyperactivity disorder (ADHD). We investigated reward-related learning in the SHR, comparing them to Sprague-Dawley (SD) rats as a reference strain. A standard Pavlovian conditioned approach task was used, in which a lever cue was followed by reward. Lever presses could occur while the lever was extended, but had no effect on reward delivery. The behavior of both the SHRs and the SD rats showed that they learnt that the lever cue predicted reward. However, the pattern of behavior differed between the strains. During lever cue presentation, SD rats pressed the lever more often and made fewer magazine entries than SHRs. When lever contacts that did not result in lever presses were analyzed, there was no significant difference between SHRs and SDs. These results suggest that the SHRs attributed less incentive value to the conditioned stimulus than the SD rats. During the presentation of the conditioned cue, cue directed responses are called sign tracking responses, whereas responses directed towards the food magazine are called goal tracking responses. Analysis of behavior using a standard Pavlovian conditioned approach index to quantify sign and goal tracking tendencies showed that both strains had a tendency towards goal tracking in this task. However, the SHRs showed a significantly greater goal tracking tendency than the SD rats. Taken together, these findings suggest that attribution of incentive value to reward predicting cues is attenuated in SHRs, which might explain their elevated sensitivity to delay of reward.

Serotonin and Dopamine Blood Levels in ADHD-Like Dogs

As with humans, dogs can suffer from attention deficit hyperactivity disorder-like (ADHD-like) behaviors naturally and exhibit high levels of hyperactivity/impulsivity and attention deficit problems, making the domestic dog a potential animal model for ADHD. ADHD has a very complex pathophysiology in which many neurotransmitters are involved, such as serotonin and dopamine. The aim of the study was to evaluate serum serotonin and dopamine levels in dogs with ADHD-like symptomatology. Fifty-eight dogs were studied, of which, thirty-six were classified as ADHD-like after physical and behavioral assessments. Additionally, the dogs’ owners performed a series of scientifically validated questionnaires which included C-BARQ, the Dog Impulsivity Assessment Scale, and the Dog-ADHD rating scale. Serum from every animal was collected after the behavioral assessments and analyzed with commercial ELISA tests for serotonin and dopamine determination. Kruskal–Wallis tests and Lasso regressions were applied to assess the relationships between both neurotransmitters and the ADHD-like behaviors (as assessed by clinical evaluation and through the different questionnaires). The dogs clinically classified as ADHD-like showed lower serotonin and dopamine concentrations. Further, serotonin and dopamine levels were also linked to aggression, hyperactivity, and impulsivity. Decreased serotonin concentrations were also related to fear, attachment, and touch sensitivity. Finally, it must be noted that our data suggested a strong relationship between serotonin and dopamine and ADHD-like behaviors.

Inhibitory deficits and symptoms of attention-deficit hyperactivity disorder: How are they related to effortful control?

Separate studies with clinical and community-based samples have identified an association between symptoms of attention-deficit hyperactivity disorder (ADHD) and inhibitory control deficits and ADHD and weak effortful control. We tested whether differences in effortful control explained the associations between ADHD symptoms and inhibitory control deficits, controlling for conduct problems. In a community sample, parents rated ADHD symptoms, conduct problems, effortful control, surgency and negative affect in 77 4-7-year-olds (47 girls), who performed an inhibitory control task. ADHD symptoms, deficient inhibitory control and low effortful control were correlated. Controlling for conduct problems, path analysis showed the ADHD symptoms - inhibitory control link was mediated statistically by effortful control. This focuses attention on cognitive-energetic factors associated with ADHD-related executive deficits.

Methylphenidate Enhances Spontaneous Fluctuations in Reward and Cognitive Control Networks in Children With Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Methylphenidate, a first-line treatment for attention-deficit/hyperactivity disorder (ADHD), is thought to influence dopaminergic neurotransmission in the nucleus accumbens (NAc) and its associated brain circuitry, but this hypothesis has yet to be systematically tested.

METHODS

We conducted a randomized, placebo-controlled, double-blind crossover trial including 27 children with ADHD. Children with ADHD were scanned twice with resting-state functional magnetic resonance imaging under methylphenidate and placebo conditions, along with assessment of sustained attention. We examined spontaneous neural activity in the NAc and the salience, frontoparietal, and default mode networks and their links to behavioral changes. Replicability of methylphenidate effects on spontaneous neural activity was examined in a second independent cohort.

RESULTS

Methylphenidate increased spontaneous neural activity in the NAc and the salience and default mode networks. Methylphenidate-induced changes in spontaneous activity patterns in the default mode network were associated with improvements in intraindividual response variability during a sustained attention task. Critically, despite differences in clinical trial protocols and data acquisition parameters, the NAc and the salience and default mode networks showed replicable patterns of methylphenidate-induced changes in spontaneous activity across two independent cohorts.

CONCLUSIONS

We provide reproducible evidence demonstrating that methylphenidate enhances spontaneous neural activity in NAc and cognitive control networks in children with ADHD, resulting in more stable sustained attention. Our findings identified a novel neural mechanism underlying methylphenidate treatment in ADHD to inform the development of clinically useful biomarkers for evaluating treatment outcomes.

Everyday Cognitive Control and Emotion Dysregulation in Young Adults With and Without ADHD: An Ecological Momentary Assessment Study

OBJECTIVE

This study examined the contribution of the temporal dynamics of two cognitive control mechanisms-inhibitory control (IC) and working memory (WM)-to emotion dysregulation (ED) in attention-deficit/hyperactivity disorder (ADHD) in ecological settings.

METHOD

One hundred twenty-two participants (age 18-33 years; 60 with ADHD) reported their ED at baseline, followed by a 5-day ecological momentary assessment (EMA) study, with short behavioral IC and WM tasks performed five times/day.

RESULTS

For IC, mean and lability of performance over EMA significantly accounted for differences in ED but not baseline performance. For WM, both baseline and mean of EMA, but not EMA lability, accounted for ED variance. ADHD status further contributed to the explained variance of ED.

CONCLUSIONS

Our results support the contribution of dynamic IC processes to ED in ADHD, in addition to WM performance level, and highlight the importance of dynamic and ecological investigation of different cognitive control components.

A behavioral timing intervention upregulates striatal serotonergic markers and reduces impulsive action in adult male mice

Many studies support the hypothesis that time-based interventions reduce impulsive behavior in rodents. However, few studies have directly assessed 1) how such interventions affect impulsive action rather than impulsive choice, 2) if intervention effects differ by sex, and 3) how time-based interventions affect neurochemistry in regions mediating decision-making and reward. Thus, we assessed how a fixed-interval (FI) intervention initiated during late adolescence and extending into adulthood affected dopaminergic and serotonergic analytes in the frontal cortex and striatum and subsequent impulsive action in adult male and female mice. Beginning on postnatal day (PND) 45, mice were either trained on a progressive series of FI schedules (FI 20, 40, & 60 s) or remained in the home cage. Following the intervention, increases in striatal serotonergic analytes were found in FI-exposed males and females (n = 8/sex/group) with few changes found in the frontal cortex. Impulsive action was assessed in the remaining mice (n = 10/sex/group) using a fixed-ratio waiting-for-reward (FR-wait) task in which completion of an FR-25 component initiated a "free" pellet component in which pellets were delivered at increasing intervals according to a fixed delay increment that varied across sessions. Responses reset the additive delay and initiated a new FR-25 component. FI-exposed males, but not females, showed fewer delay resets and no-wait resets relative to control mice. Importantly, FI-exposure did not affect discrimination reversal performance in either sex. These data suggest that time-based interventions may reduce impulsive action in addition to impulsive choice perhaps with increased male sensitivity. Additionally, time-based interventions appear to operate through striatal serotonergic augmentation.

Near and Far Transfer Effects of Computerized Progressive Attention Training (CPAT) Versus Mindfulness Based Stress Reduction (MBSR) Practice Among Adults With ADHD

OBJECTIVE

The present study evaluated the near (attention) and far (reading, ADHD symptoms, learning, and quality of life) transfer effects of a Computerized Progressive Attention Training (CPAT) versus Mindfulness Based Stress Reduction (MBSR) practice among adults with ADHD compared to a passive group.

METHOD

Fifty-four adults participated in a non-fully randomized controlled trial. Participants in the intervention groups completed eight 2-hr weekly training sessions. Outcomes were assessed before, immediately after, and 4 months post-intervention, using objective tools: attention tests, eye-tracker, and subjective questionnaires.

RESULTS

Both interventions showed near-transfer to various attention functions. The CPAT produced far-transfer effects to reading, ADHD symptoms, and learning while the MBSR improved the self-perceived quality of life. At follow-up, all improvements except for ADHD symptoms were preserved in the CPAT group. The MBSR group showed mixed preservations.

CONCLUSION

Both interventions have beneficial effects, however only the CPAT group exhibited improvements compared to the passive group.

Perspectives on heterogeneity-informed cognitive training for attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (AD/HD) is a heterogeneous neurodevelopmental condition, posing a severe threat to quality of life. Pharmacological therapies are the front-line treatment; however, their shortages encourage the development of alternative treatments for AD/HD. One promising method of developing alternative treatments is cognitive training (CT). A CT-based therapy was recently approved by the US Food and Drug Administration. However, due to heterogeneity in AD/HD, a CT protocol is unlikely to provide a one-size-fits-all solution for all patients with AD/HD. Therefore, this article highlights key aspects that need to be considered to further develop CT protocols for AD/HD, regarding training content, timing, suitability, and delivery mode. The perspectives presented here contribute to optimizing CT as an alternative option for treating AD/HD.

Longitudinal investigation in children and adolescents with ADHD and healthy controls: A 2-year ERP study

Cross-sectional group comparisons have shown altered neurocognitive and neurophysiological profiles in individuals with attention-deficit/hyperactivity disorder (ADHD). We report a two-year longitudinal observational study of ADHD children and adolescents (N = 239) regarding ADHD symptoms, behavioral metrics, and event-related potentials (ERP) and compared them to healthy controls (N = 91). The participants were assessed up to five times with a cued Go/NoGo task while ERPs were recorded. We fitted the trajectories of our variables of interest with univariate and bivariate latent growth curve models. At baseline, the ADHD group had increased reaction time variability, higher number of omission and commission errors, and attenuated CNV and P3d amplitudes compared to controls. The task performance in terms of behavioral metrics improved in both groups over two years; however, with differential patterns: the decrease in reaction time and omission errors were stronger in the control group, and the reduction of commission errors was more substantial in the ADHD group. The cueP3, CNV, and N2d amplitudes changed slightly over two years, with negligible differences between both groups. Furthermore, the parent-rated symptom burden in the ADHD group decreased by 22 % (DSM-5-based questionnaire). We did not identify any associations between the changes in symptoms and the changes in the behavioral or neurophysiological metrics. The lack of association between the changes in symptoms and the behavioral or ERP metrics supports the trait liability hypothesis, which claims that the neurocognitive deficits are independent of symptom alleviation. Furthermore, the change in symptom burden was substantial, questioning the stability of the reported ADHD symptoms.

The effects of bilingualism on cognition and behaviour in individuals with attention deficits: A scoping review

Background

Weaknesses in executive function have persistently been found to be associated with Attention Deficit Hyperactivity Disorder (ADHD), while bilinguals have been argued to show advantages in executive functions. While there has been some research into how bilingualism affects cognitive skills and behaviour in individuals with attention deficits, the question is still very much open. The aim of this systematic review is to gather, synthesise and evaluate existing evidence on how bilingual language experience and attention deficits affect executive function performance and ADHD-related symptoms in children and adults.

Methods

Following PRISMA guidelines, a comprehensive literature search in relevant databases (PsycInfo, PubMed, Scopus, ERIC, Web of Science, EMBASE, MEDLINE, LLBA) was performed using search strings related to attention difficulties/ADHD and bilingualism. All quantitative studies were included that presented original empirical data on the combined effects of bilingualism and attention levels, regardless of age group and methodology. The screening procedure revealed nine relevant studies.

Results

Across the nine identified studies, a total of 2071 participants were tested. Of these, seven studies involved children and two adults. The studies varied considerably with respect to their design and methodology, the targeted executive function skills or behavioural symptoms, as well as their measure of bilingualism and attention levels. Most studies assessed aspects of executive function performance such as interference control, response inhibition, working memory or cognitive flexibility. Three studies looked at the effects of bilingualism on ADHD-related symptoms or ADHD diagnosis. Across the studies, no systematic advantage or disadvantage of bilingualism on cognitive performance or behaviour in people with attention deficits was observed.

Conclusion

The limited number of identified studies provide no consistent evidence that bilingualism alleviates or intensifies attention difficulties in adults or children with ADHD. Based on the current state of research, individuals with ADHD and their families should not be concerned that learning additional languages has a negative impact on functioning or cognitive performance.

Systematic review registration

https://doi.org/10.17605/OSF.IO/PK768.

Effect of methylphenidate on functional controllability: a preliminary study in medication-naïve children with ADHD

Methylphenidate (MPH) is the recommended first-line treatment for attention-deficit/hyperactivity disorder (ADHD). While MPH's mechanism of action as a dopamine and noradrenaline transporter blocker is well known, how this translates to ADHD-related symptom mitigation is still unclear. As functional connectivity is reliably altered in ADHD, with recent literature indicating dysfunctional connectivity dynamics as well, one possible mechanism is through altering brain network dynamics. In a double-blind, placebo-controlled MPH crossover trial, 19 medication-naïve children with ADHD underwent two functional MRI scanning sessions (one on MPH and one on placebo) that included a resting state scan and two inhibitory control tasks; 27 typically developing (TD) children completed the same protocol without medication. Network control theory, which quantifies how brain activity reacts to system inputs based on underlying connectivity, was used to assess differences in average and modal functional controllability during rest and both tasks between TD children and children with ADHD (on and off MPH) and between children with ADHD on and off MPH. Children with ADHD on placebo exhibited higher average controllability and lower modal controllability of attention, reward, and somatomotor networks than TD children. Children with ADHD on MPH were statistically indistinguishable from TD children on almost all controllability metrics. These findings suggest that MPH may stabilize functional network dynamics in children with ADHD, both reducing reactivity of brain organization and making it easier to achieve brain states necessary for cognitively demanding tasks.

Inconsistencies between Subjective Reports of Cognitive Difficulties and Performance on Cognitive Tests are Associated with Elevated Internalising and Externalising Symptoms in Children with Learning-related Problems

Children with learning difficulties are commonly assumed to have underlying cognitive deficits by health and educational professionals. However, not all children referred for psycho-educational assessment will be found to have deficits when their abilities are measured by performance on cognitive tasks. The primary aim of this study was to estimate the prevalence of this inconsistent cognitive profile (ICP) in a transdiagnostic sample of children referred by health and education service providers for problems related to attention, learning and memory (N = 715). A second aim was to explore whether elevated mental health problems were associated with ICPs. Findings suggest that approximately half of this sample could be characterised as having an ICP. Cognitive difficulties, whether identified by parent ratings or task performance, were associated with elevated internalising and externalising difficulties. Crucially, a larger discrepancy between a parent's actual ratings of a child's cognitive difficulties and the ratings that would be predicted based on the child's performance on cognitive tasks was associated greater internalising and externalising difficulties for measures of working memory, and greater externalising difficulties for measures of attention. These findings suggest that subjective cognitive difficulties occurring in the absence of any task-based performance deficits may be a functional problem arising from mental health problems.

Ignore the glitch but mind the switch: Positive effects of methylphenidate on cognition in attention deficit hyperactivity disorder are related to prediction gain

Neuropsychological symptoms such as inattention and distractibility constitute a core characteristic of attention deficit hyperactivity disorder (ADHD). Here, we tested the hypothesis that attentional dysfunctions result from a deficit in neural gain modulation, which translates into difficulty in predictively weighting relevant sensory input while ignoring distraction. We compared thirty-seven hitherto untreated adults diagnosed with ADHD and thirty-eight healthy participants with a serial switch-drift task that requires internal models of predictable digit sequences to be either updated or stabilized. Switches between sequences that had to be indicated by key presses and digit omissions within a sequence (drifts) that should be ignored varied by stimulus-bound surprise quantified as Shannon information. To investigate whether catecholaminergic modulation by increasing extracellular norepinephrine and dopamine levels leads to an amelioration in prediction gain, participants were tested twice, with patients receiving a single dose of methylphenidate, a norepinephrine/dopamine reuptake inhibitor, in the second session. Patients and controls differed in both updating and stabilizing, depending on the respective event surprise. Specifically, patients showed difficulty in detecting expectable switches, while having greater difficulty to ignore surprising distractions. Thus, underconfident prior beliefs in ADHD may fail to appropriately weight expected relevant input, whereas the gain of neural responses to unexpected irrelevant distractors is increased. Methylphenidate improved both flexibility and stability of prediction and had a positive effect on selective responding over time. Our results suggest that ADHD is associated with an impairment in the use of prior expectations to optimally weight sensory inputs, which is improved by increasing catecholaminergic neurotransmission.

Proposal for an Integrative Cognitive-Emotional Conception of ADHD

Although numerous efforts have been made to deepen our understanding of the etiology of Attention Deficit Hyperactivity Disorder (ADHD), no explanation of its origins, nor of its consequences, has yet found a consensus within the scientific community. This study performs a theoretical review of various research studies and provides a reflection on the role of emotions in the origin of the disorder, at the neuroanatomical and functional level. To this end, theoretical models (single and multiple origin) and applied studies are reviewed in order to broaden the perspective on the relevance of the executive system in ADHD; it is suggested that this construct is not only composed and activated by cognitive processes and functions, but also includes elements of an emotional and motivational nature. Consequently, it is shown that ADHD is involved in social development and in a person's ability to adapt to the environment.

Assessment of 'Cool' and 'Hot' Executive Skills in Children with ADHD: The Role of Performance Measures and Behavioral Ratings

Executive dysfunction is an underlying characteristic of Attention Deficit/Hyperactivity Disorder (ADHD). Therefore, this study explored which measures of executive functions (EF) may lead to a better diagnostic prediction and evaluated whether participants were adequately assigned to the ADHD group based on the identified predictors. Seventeen 6- to 10-year-old children with ADHD were matched with 17 typically developing peers (TD) by age, gender, and non-verbal intelligence. Performance-based measures and behavior ratings of 'cool' and 'hot' EF were used. As expected, there was a significant group effect on the linear combination of measures, indicating that children with ADHD showed significant difficulties with EF compared to the TD group. In fact, significant differences were found in measures of short-term and working memory, planning, delay aversion, and EF-related behaviors, as reported by parents and teachers. However, the discriminant function analysis only revealed three significant predictors: the General Executive Composite of the Behavior Rating Inventory of Executive Function (Parent and Teacher Forms) and the Delay of Gratification Task, with 97.1% correct classifications. These findings highlight the importance and contribution of both behavioral ratings and 'hot' measures of EF for the characterization of ADHD in children.

Promoting academic success in college students with ADHD and LD: A systematic literature review to identify intervention targets

Objective: College students with attention-deficit/hyperactivity disorder (ADHD) and/or a learning disorder (LD) are at higher risk for not attaining a bachelor's degree. The purpose is to identify the predictors of academic success in college for students with ADHD and/or LD using a systematic review of the literature. Method: Academic Search Premier, Education Full Text, Education Source, Education Resources Information Center, Teacher Reference Center, PsycINFO, PsycArticles, and Primary Search and relevant journals were searched using PRISMA guidelines. Studies were screened based on the following inclusion criteria: college students with ADHD and/or LD, student characteristics as predictors, and GPA and/or retention as outcomes. Results: Twenty-one studies were included (20 quantitative studies and 1 randomized control trial). Academic regulation, academic self-efficacy, emotional regulation, ADHD symptoms, and academic and social integration predicted college success. Conclusion: Incorporating these components into interventions with students with ADHD and/or LD may enhance their success in college.

Neuroprotection in late life attention-deficit/hyperactivity disorder: A review of pharmacotherapy and phenotype across the lifespan

For decades, psychostimulants have been the gold standard pharmaceutical treatment for attention-deficit/hyperactivity disorder (ADHD). In the United States, an astounding 9% of all boys and 4% of girls will be prescribed stimulant drugs at some point during their childhood. Recent meta-analyses have revealed that individuals with ADHD have reduced brain volume loss later in life (>60 y.o.) compared to the normal aging brain, which suggests that either ADHD or its treatment may be neuroprotective. Crucially, these neuroprotective effects were significant in brain regions (e.g., hippocampus, amygdala) where severe volume loss is linked to cognitive impairment and Alzheimer's disease. Historically, the ADHD diagnosis and its pharmacotherapy came about nearly simultaneously, making it difficult to evaluate their effects in isolation. Certain evidence suggests that psychostimulants may normalize structural brain changes typically observed in the ADHD brain. If ADHD itself is neuroprotective, perhaps exercising the brain, then psychostimulants may not be recommended across the lifespan. Alternatively, if stimulant drugs are neuroprotective, then this class of medications may warrant further investigation for their therapeutic effects. Here, we take a bottom-up holistic approach to review the psychopharmacology of ADHD in the context of recent models of attention. We suggest that future studies are greatly needed to better appreciate the interactions amongst an ADHD diagnosis, stimulant treatment across the lifespan, and structure-function alterations in the aging brain.

Investigation of white matter functional networks underlying different behavioral profiles in attention-deficit/hyperactivity disorder

Background

Cortical functional network alterations have been widely accepted as the neural basis of attention-deficit/hyperactivity disorder (ADHD). Recently, white matter has also been recognized as a novel neuroimaging marker of psychopathology and has been used as a complement to cortical functional networks to investigate brain-behavior relationships. However, disorder-specific features of white matter functional networks (WMFNs) are less well understood than those of gray matter functional networks. In the current study, we constructed WMFNs using a new strategy to characterize behavior-related network features in ADHD.

Methods

We recruited 46 drug-naïve boys with ADHD and 46 typically developing (TD) boys, and used clustering analysis on resting-state functional magnetic resonance imaging data to generate WMFNs in each group. Intrinsic activity within each network was extracted, and the associations between network activity and behavior measures were assessed using correlation analysis.

Results

Nine WMFNs were identified for both ADHD and TD participants. However, boys with ADHD showed a splitting of the inferior corticospinal-cerebellar network and lacked a cognitive control network. In addition, boys with ADHD showed increased activity in the dorsal attention network and somatomotor network, which correlated positively with attention problems and hyperactivity symptom scores, respectively, while they presented decreased activity in the frontoparietal network and frontostriatal network in association with poorer performance in response inhibition, working memory, and verbal fluency.

Conclusions

We discovered a dual pattern of white matter network activity in drug-naïve ADHD boys, with hyperactive symptom-related networks and hypoactive cognitive networks. These findings characterize two distinct types of WMFN in ADHD psychopathology.

A systematic review of randomized controlled trials on efficacy and safety of transcranial direct current stimulation in major neurodevelopmental disorders: ADHD, autism, and dyslexia

OBJECTIVE

Among the target groups in child and adolescent psychiatry, transcranial direct current stimulation (tDCS) has been more applied in neurodevelopmental disorders specifically, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and dyslexia. This systematic review aims to provide the latest update on published randomized-controlled trials applying tDCS in these disorders for evaluating its efficacy and safety.

METHODS

Based on a pre-registered protocol (PROSPERO: CRD42022321430) and using the PRISMA approach, a literature search identified 35 randomized controlled trials investigating the effects of tDCS on children and adolescents with ADHD (n = 17), ASD (n = 11), and dyslexia (n = 7).

RESULTS

In ADHD, prefrontal anodal tDCS is reported more effective compared to stimulation of the right inferior frontal gyrus. Similarly in ASD, prefrontal anodal tDCS was found effective for improving behavioral problems. In dyslexia, stimulating temporoparietal regions was the most common and effective protocol. In ASD and dyslexia, all tDCS studies found an improvement in at least one of the outcome variables while 64.7% of studies (11 of 17) in ADHD found a similar effect. About 88% of all tDCS studies with a multi-session design in 3 disorders (16 of 18) reported a significant improvement in one or all outcome variables after the intervention. Randomized, double-blind, controlled trials consisted of around 70.5%, 36.3%, and 57.1% of tDCS studies in ADHD, ASD, and dyslexia, respectively. tDCS was found safe with no reported serious side effects in 6587 sessions conducted on 745 children and adolescents across 35 studies.

CONCLUSION

tDCS was found safe and partially effective. For evaluation of clinical utility, larger randomized controlled trials with a double-blind design and follow-up measurements are required. Titration studies that systematically evaluate different stimulation intensities, duration, and electrode placement are lacking.

Event rate effects on children with attention-deficit/hyperactive disorder: Test predictions from the moderate brain arousal model and the neuro-energetics theory using the diffusion decision model

BACKGROUND

Converging evidence has found that the inhibitory control of children with attention-deficit/hyperactive disorder (ADHD) is context-dependent and particularly susceptible to the event rate. The Moderate Brain Arousal (MBA) model predicts a U-shaped curve between event rate and performance as a modulation of brain arousal. The neuroenergetics theory (NeT) proposes that a smaller event rate results in neuronal fatigue and subsequent descent performance. However, previous work applied the traditional one-dimensional index of performance, such as accuracy rate and response time, which might limit the exploration of the event rate effect on the specific underlying process.

AIMS

We used a diffusion decision model (DDM) to study the influence of event rate on inhibition control in children with ADHD and verified the explanation of the MBA model and the NeT.

METHODS AND PROCEDURES

The Stop Signal Task manipulated by four event rate conditions was conducted with 24 children with ADHD (mean age=8.5, males=16) and 29 typical developmental children (TDC) (mean age=9.0, males=12). DDM was applied to compare the differences in the DDM parameters across different event rates.

OUTCOMES AND RESULTS

Compared with TDC, children with ADHD had a smaller drift rate, longer non-decision time, and smaller boundary separation. Although the event rate had little influence on ADHD, the drift rate of the TDC was approximately linear with an increased event rate, and the Ter had a quadratic function relationship with the event rate.

CONCLUSIONS AND IMPLICATIONS

The event rate effect may influence children's performance through dual mechanisms. Neuronal energy supply could regulate information processing and brain arousal to regulate the activation of primary stimuli encoding and motor control. Insight into the multi-mechanism of ADHD cognition deficits would be helpful for clinicians in making objective diagnoses and effective targeted treatments.

Adult-Onset ADHD: A Critical Analysis and Alternative Explanations

Attention deficit/hyperactivity disorder (ADHD) is characterized as a neurodevelopmental disorder. However, data from several recent studies suggest that there may be adults who meet current criteria for ADHD, yet did not experience symptoms until adulthood (i.e., "adult-onset ADHD"). This systematic review evaluated and synthesized the empirical evidence on adult-onset ADHD to answer the question: Is the extant literature strong enough to evaluate adult-onset ADHD? Nine studies met strict inclusion/exclusion criteria. Results suggest that the methodologies of the extant studies were not strong enough to evaluate adult-onset ADHD. Insufficient methodologies provide presently unclear information about the nature of late-onset symptoms. These symptoms seem to exist but their source could be (1) adult-emergent symptoms that were previously surpassed due to lower environmental demands/supportive facilitators, (2) mimics that were not properly assessed, or (3) childhood-onset symptoms that were not detected earlier due to failure to come to clinical attention. Future directions, clinical recommendations, and limitations of the literature and the current review are discussed.

Brain Signatures During Reward Anticipation Predict Persistent Attention-Deficit/Hyperactivity Disorder Symptoms

OBJECTIVE

Children experiencing attention-deficit/hyperactivity disorder (ADHD) symptoms may retain symptoms into adulthood, but little is known about the underlying mechanism.

METHOD

To identify biomarkers of persistent ADHD symptom development, we carried out whole-brain analyses of neuroimaging data during the anticipation phase of the Monetary-Incentive-Delay (MID) task in 1,368 adolescents recruited by the IMAGEN Consortium at age 14 years, whose behavioral measurements were followed up longitudinally at age 16. In particular, we focused on comparing individuals with persistent high ADHD symptoms at both ages 14 and 16 years to unaffected control individuals, but also exploring which individuals demonstrating symptom remission (with high ADHD symptoms at age 14 but much reduced at age 16).

RESULTS

We identified reduced activations in the medial frontal cortex and the thalamus during reward anticipation as neuro-biomarkers for persistent ADHD symptoms across time. The genetic relevance of the above findings was further supported by the associations of the polygenic risk scores of ADHD with both the persistent and control status and the activations of both brain regions. Furthermore, in an exploratory analysis, the thalamic activation might also help to distinguish persons with persistent ADHD from those remitted in both an exploratory sample (odds ratio = 9.43, p < .001) and an independent generalization sample (odds ratio = 4.64, p = .003).

CONCLUSION

Using a well-established and widely applied functional magnetic resonance imaging task, we have identified neural biomarkers that could discriminate ADHD symptoms that persist throughout adolescence from controls and potentially those likely to remit during adolescent development as well.

Developmental Risk, Adversity Experiences and ADHD Clinical Profiles: A Naturalistic Exploratory Study

Attention-deficit/hyperactivity disorder (ADHD) is a persistent neurodevelopmental disorder that results from complex interactions of multiple genes and environmental risk and adversity factors. Some researchers have suggested a need for additional research into differing clinical presentations of ADHD for further classification. In this context, this study aimed to investigate whether increases in risk and adversity factors increase the severity of ADHD and the number of comorbid psychiatric disorders. This is a naturalistic retrospective chart review exploratory study in 100 patients 16 years or older who have a confirmed diagnosis of ADHD. The quantitative data were analyzed using SPSS, using the Mann–Whitney test for parametric data and the Chi-square and Kruskal–Wallis p value tests for non-parametric and categorical data. Qualitative data were tabulated and described. The study found that (1) the average number of comorbidities increases with the severity of ADHD, (2) the average number of risk and adversity factors increases with the severity of ADHD, (3) the number of risk and adversity factors were positively associated with the number of comorbidities, and (4) Level of education was negatively associated with the number of risk and adversity factors and the number of comorbidities. The implications of these findings are discussed, and future research in this important area is suggested.

Qualitative variations in delay discounting: A brief review and future directions

The discounting paradigm has been challenged by an increasing number of studies presenting qualitative variations in the individual discount function. Particularly, the subjective value of a loss does not necessarily systematically decrease with delay to the outcome. Qualitative variation refers to variations in shape rather than steepness of the discount function, such as positive discounting, zero discounting, unsystematic discounting, and negative discounting. Data from three previous studies were analysed in terms of qualitative variations observed in delay discounting patterns. Attention was also given to methods used and to the relationship between the results from the various levels of investigation. We found qualitative differences between discounting of monetary gains and losses on an individual level. While discounting of gains mainly took the form of conventional positive discounting, discounting of losses often took the form of zero discounting or unsystematic discounting. Further, there were more qualitative variations in discounting of both gains and losses among adolescents compared to adults. By examining verbal reports and single choices, we identified some of the rules and consequences involved in these delay discounting patterns. The different rules and consequences observed for the gain and loss scenarios, support that discounting of gains and losses may involve different combinations of reinforcing contingencies. These results point towards a possible way to explain the influences of qualitative variations in delay discounting.

White matter microstructure in children and adolescents with ADHD

•

A systematic review of diffusion MRI studies in children and adolescents with ADHD.

•

46 studies included, encompassing multiple diffusion MRI techniques.

•

Reduced white matter microstructure was reported in several studies.

•

Mixed evidence linking white matter differences with specific cognitive processes.

•

Common limitations included sample size, head motion and medication status.

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Advances in diffusion magnetic resonance imaging (MRI) acquisition sequences and analytic techniques have led to growing body of evidence that abnormal white matter microstructure is a core pathophysiological feature of ADHD. This systematic review provides a qualitative assessment of research investigating microstructural organisation of white matter amongst children and adolescents with ADHD. This review included 46 studies in total, encompassing multiple diffusion MRI imaging techniques and analytic approaches, including whole-brain, region of interest and connectomic analyses. Whole-brain and region of interest analyses described atypical organisation of white matter microstructure in several white matter tracts: most notably in frontostriatal tracts, corpus callosum, superior longitudinal fasciculus, cingulum bundle, thalamic radiations, internal capsule and corona radiata. Connectomic analyses, including graph theory approaches, demonstrated global underconnectivity in connections between functionally specialised networks. Although some studies reported significant correlations between atypical white matter microstructure and ADHD symptoms or other behavioural measures there was no clear pattern of results. Interestingly however, many of the findings of disrupted white matter microstructure were in neural networks associated with key neuropsychological functions that are atypical in ADHD. Limitations to the extant research are outlined in this review and future studies in this area should carefully consider factors such as sample size, sex balance, head motion and medication status.

Treatment with RehaCom computerized rehabilitation program improves response control, but not attention in children with attention-deficit/hyperactivity disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD) is a common psychiatric disorder in children. ADHD impairs attention, response control, emotion regulation, and other cognitive functions. On the other hand, RehaCom is a cognitive rehabilitation software that has therapeutic effects on cognitive dysfunctions in many diseases such as stroke, multiple sclerosis, and schizophrenia. The goal of the present study was to investigate the effect of treatment with RehaCom on auditory and visual response control, and auditory and visual attention in children with ADHD. Forty patients were selected. The participants were assigned to control (n = 20) and experimental (n = 20) groups, while only the participants in the experimental group were trained by RehaCom for five weeks (ten 45-min sessions, two sessions per week). At weeks 0 and 5, performance of the participants of experimental group was compared with the participants of control group. The results showed that treatment with RehaCom significantly improved auditory and visual response control in children with ADHD, with no effect on auditory and visual attention. In conclusion, RehaCom may alter brain's structural and functional properties that are related to response control. We suggest that attention deficit in ADHD may be a result of more complicated dysfunctions in the brain, that are not affected by RehaCom.