Cognitive control in children with ADHD-C: how efficient are they?

Perceived Expressed Emotion and Irritability in Adolescents With Attention-Deficit/Hyperactivity Disorder Inattentive Type: The Moderating Effect of Subtype

The current study aimed to investigate perceived expressed emotion (EE) and irritability among adolescents with inattentive and combined type attention-deficit/hyperactivity disorder (ADHD-I and ADHD-C, respectively), and to assess whether the subtype plays a moderating role in the relationship between perceived EE and irritability. The current cross-sectional, case-control study comprised 37 adolescents with ADHD-I, 62 adolescents with ADHD-C, and 58 age- and sex-matched adolescents without ADHD. After controlling for confounding factors, adolescents with ADHD-C were found to exhibit significantly higher levels of perceived lack of emotional support than adolescents with ADHD-I (p = 0.029). Results of moderation analysis showed ADHD subtype to be a moderating factor in the relationship between perceived EE and irritability. [Journal of Psychosocial Nursing and Mental Health Services, xx(xx), xx-xx.].

Task-generic and task-specific connectivity modulations in the ADHD brain: an integrated analysis across multiple tasks

Attention-deficit/hyperactivity disorder (ADHD) is associated with altered functioning in multiple cognitive domains and neural networks. This paper offers an overarching biological perspective across these. We applied a novel strategy that extracts functional connectivity modulations in the brain across one (P_single), two (P_mix) or three (P_all) cognitive tasks and compared the pattern of modulations between participants with ADHD (n-89), unaffected siblings (n = 93) and controls (n = 84; total N = 266; age range = 8-27 years). Participants with ADHD had significantly fewer P_all connections (modulated regardless of task), but significantly more task-specific (P_single) connectivity modulations than the other groups. The amplitude of these P_single modulations was significantly higher in ADHD. Unaffected siblings showed a similar degree of P_all connectivity modulation as controls but a similar degree of P_single connectivity modulation as ADHD probands. P_all connections were strongly reproducible at the individual level in controls, but showed marked heterogeneity in both participants with ADHD and unaffected siblings. The pattern of reduced task-generic and increased task-specific connectivity modulations in ADHD may be interpreted as reflecting a less efficient functional brain architecture due to a reduction in the ability to generalise processing pathways across multiple cognitive domains. The higher amplitude of unique task-specific connectivity modulations in ADHD may index a more "effortful" coping strategy. Unaffected siblings displayed a task connectivity profile in between that of controls and ADHD probands, supporting an endophenotype view. Our approach provides a new perspective on the core neural underpinnings of ADHD.

The dynamics of theta-related pro-active control and response inhibition processes in AD(H)D

Impulsivity and deficits in response inhibition are hallmarks of attention-deficit(-hyperactivity) disorder (AD(H)D), can cause severe problems in daily functioning, and are thus of high clinical relevance. Traditionally, research to elucidate associated neural correlates has intensively, but also quite selectively examined mechanisms during response inhibition in various tasks. Doing so, in-between trial periods or periods prior to the response inhibition process, where no information relevant to inhibitory control is presented, have been neglected. Yet, these periods may nevertheless reveal relevant information. In the present study, using a case-control cross-sectional design, we take a more holistic approach, examining the inter-relation of pre-trial and within-trial periods in a Go/Nogo task with a focus on EEG theta band activity. Applying EEG beamforming methods, we show that the dynamics between pre-trial (pro-active) and within-trial (inhibition-related) control processes significantly differ between AD(H)D subtypes. We show that response inhibition, and differences between AD(H)D subtypes, exhibit distinct patterns of (at least) three factors: (i) strength of pre-trial (pro-active control) theta-band activity, (ii) the inter-relation of pro-active control and inhibition-relation theta band activity and (iii) the functional neuroanatomical region active during theta-related pro-active control processes. This multi-factorial pattern is captured by AD(H)D subtype clinical symptom clusters. The study provides a first hint that novel cognitive-neurophysiological facets of AD(H)D may be relevant to distinguish AD(H)D subtypes.

Intact Context-Dependent Modulation of Conflict Monitoring in Childhood ADHD

Objective: Conflict monitoring is well known to be modulated by context. This is known as the Gratton effect, meaning that the degree of interference is smaller when a stimulus-response conflict had been encountered previously. It is unclear to what extent these processes are changed in ADHD. Method: Children with ADHD (combined subtype) and healthy controls performed a modified version of the sequence flanker task. Results: Patients with ADHD made significantly more errors than healthy controls, indicating general performance deficits. However, there were no differences regarding reaction times, indicating an intact Gratton effect in ADHD. These results were supported by Bayesian statistics. Conclusion: The results suggest that the ability to take contextual information into account during conflict monitoring is preserved in patients with ADHD despite this disorder being associated with changes in executive control functions overall. These findings are discussed in light of different theoretical accounts on contextual modulations of conflict monitoring.

Neurofeedback trains a superordinate system relevant for seemingly opposing behavioral control deficits depending on ADHD subtype

ADHD is one of the most prevalent neuropsychiatric disorders of childhood, but symptoms vary considerably between individuals. Therefore, different ADHD subtypes can be distinguished. Yet, it is widely elusive whether the specific subtype is critical to consider when examining treatment effects. Based on theoretical considerations, this could be the case for EEG theta/beta neurofeedback. We examine the effects of such an intervention on rapid response execution and inhibition processes using a Go/Nogo task in the inattentive (ADD) and the combined (ADHD-C) subtype. We show that a single neurofeedback protocol affects opposing deficits depending on the ADHD subtype - namely the execution (in ADD) and inhibition of action (in ADHD-C). No changes occurred in the healthy controls. These findings are discussed in relation to overarching principles of neural oscillations, particularly in the beta frequency band. The data suggest that theta/beta neurofeedback trains a superordinate system strongly related to the function of neural beta frequency oscillations to tune neural networks important for the sampling of sensory information used for behavioral control.

Intact Stimulus-Response Conflict Processing in ADHD-Multilevel Evidence and Theoretical Implications

Attention-deficit-hyperactivity disorder (ADHD) is closely associated with deficits in cognitive control. It seems, however, that the degree of deficits strongly depends on the examined subprocess, with the resolution of stimulus–stimulus conflicts being particularly difficult for patients with ADHD. The picture is far less clear regarding stimulus–response conflicts. The current study provides multi-level behavioural and neurophysiological data on this type of conflict monitoring in children with ADHD compared to healthy controls. To account for the potentially strong effects of intra-individual variability, electroencephalogram (EEG) signal decomposition methods were used to analyze the data. Crucially, none of the analyses (behavioural, event-related potentials, or decomposed EEG data) show any differences between the ADHD group and the control group. Bayes statistical analysis confirmed the high likelihood of the null hypothesis being true in all cases. Thus, the data provide multi-level evidence showing that conflict monitoring processes are indeed partly intact in ADHD, even when eliminating possible biasing factors such as intra-individual variability. While stimulus–stimulus conflict processing has been shown to be consistently dysfunctional in ADHD, the resolution of stimulus–response conflicts is not deficient in this patient group. In comparison to other studies, the results provide novel theoretical insights into the nature of conflict control deficits in childhood ADHD.

Deep Learning Based on Event-Related EEG Differentiates Children with ADHD from Healthy Controls

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent neuropsychiatric disorders in childhood and adolescence and its diagnosis is based on clinical interviews, symptom questionnaires, and neuropsychological testing. Much research effort has been undertaken to evaluate the usefulness of neurophysiological (EEG) data to aid this diagnostic process. In the current study, we applied deep learning methods on event-related EEG data to examine whether it is possible to distinguish ADHD patients from healthy controls using purely neurophysiological measures. The same was done to distinguish between ADHD subtypes. The results show that the applied deep learning model (“EEGNet”) was able to distinguish between both ADHD subtypes and healthy controls with an accuracy of up to 83%. However, a significant fraction of individuals could not be classified correctly. It is shown that neurophysiological processes indicating attentional selection associated with superior parietal cortical areas were the most important for that. Using the applied deep learning method, it was not possible to distinguish ADHD subtypes from each other. This is the first study showing that deep learning methods applied to EEG data are able to dissociate between ADHD patients and healthy controls. The results show that the applied method reflects a promising means to support clinical diagnosis in ADHD. However, more work needs to be done to increase the reliability of the taken approach.

Effects of multisensory stimuli on inhibitory control in adolescent ADHD: It is the content of information that matters

Even though deficits in inhibitory control and conflict monitoring are well-known in ADHD, factors that further modulate these functions remain to be elucidated. One factor that may be of considerable importance is how inhibitory control is modulated by multisensory information processing. We examined the influence of concurrent auditory conflicting or redundant information on visually triggered response inhibition processes in adolescent ADHD patients and healthy controls. We combined high-density event-related potential (ERP) recordings with source localization to delineate the functional neuroanatomical basis of the involved neurophysiological processes. In comparison to controls, response inhibition (RI) processes in ADHD were compromised in conflicting conditions, but showed no differences to controls when redundant or no concurrent auditory information was presented. These effects were reflected by modulations at the response selection stage (P3 ERP) in the medial frontal gyrus (BA32), but not at the attentional selection (P1, N1 ERPs) or resource allocation level (P2 ERP). Conflicting information during RI exerts its influences in adolescent ADHD via response selection mechanisms, but not via attentional selection. It is not the mere presence of concurrent information, but the presence of conflicting information during RI that may destabilize goal shielding processes in medial frontal cortical regions, by means of increasing the automaticity of response tendencies. The occurring RI deficits might relate to the increased impulsivity in adolescent ADHD and a corresponding vulnerability to react to an increased automaticity of pre-potent response tendencies. ADHD patients show a bias to a specific content of information which can modulate inhibitory control.

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Response inhibition (RI) performance in ADHD is modulated by multisensory information.

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Only incongruent/conflicting concurrent information modulates RI performance.

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RI deficits occur if this conflicting information braces the automaticity of response tendencies.

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These deficits relate to a predisposition of ADHD to engage in impulsive behavior.

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This may be due to deficient goal-shielding processes located in the MFG.

Neurophysiological mechanisms of interval timing dissociate inattentive and combined ADHD subtypes

It is far from conclusive what distinguishes the inattentive (ADD) and the combined (ADHD-C) subtype of ADHD on the neuronal level. Theoretical considerations suggest that especially interval timing processes may dissociate these subtypes from each other. Combining high-density EEG recordings with source localization analyses, we examine whether there are ADHD-subtype specific modulations of neurophysiological processes subserving interval timing in matched groups of ADD (n = 16), ADHD-C (n = 16) and controls (n = 16). Patients with ADD and ADHD-C show deficits in interval timing, which was correlated with the degree of inattention in ADD patients. Compared to healthy controls, patients with ADHD-C display a somewhat weaker, yet consistent response preparation process (contingent negative variation, CNV). In patients with ADD, the early CNV is interrupted, indicating an oscillatory disruption of the interval timing process. This is associated with activations in the supplemental motor areas and the middle frontal gyrus. Patients with ADD display adequate feedback learning mechanisms (feedback-related negativity, FRN), which is not the case in patients with ADHD-C. The results suggest that altered pacemaker-accumulation processes in medial frontal structures distinguish the ADD from the ADHD-C subtype. Particularly in patients with ADD phasic interruptions of preparatory neurophysiological processes are evident, making this a possible diagnostic feature.

ADHD patients fail to maintain task goals in face of subliminally and consciously induced cognitive conflicts

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) patients have been reported to display deficits in action control processes. While it is known that subliminally and consciously induced conflicts interact and conjointly modulate action control in healthy subjects, this has never been investigated for ADHD.

METHOD

We investigated the (potential) interaction of subliminally and consciously triggered response conflicts in children with ADHD and matched healthy controls using neuropsychological methods (event-related potentials; ERPs) to identify the involved cognitive sub-processes.

RESULTS

Unlike healthy controls, ADHD patients showed no interaction of subliminally and consciously triggered response conflicts. Instead, they only showed additive effects as their behavioural performance (accuracy) was equally impaired by each conflict and they showed no signs of task-goal shielding even in cases of low conflict load. Of note, this difference between ADHD and controls was not rooted in early bottom-up attentional stimulus processing as reflected by the P1 and N1 ERPs. Instead, ADHD showed either no or reversed modulations of conflict-related processes and response selection as reflected by the N2 and P3 ERPs.

CONCLUSION

There are fundamental differences in the architecture of cognitive control which might be of use for future diagnostic procedures. Unlike healthy controls, ADHD patients do not seem to be endowed with a threshold which allows them to maintain high behavioural performance in the face of low conflict load. ADHD patients seem to lack sufficient top-down attentional resources to maintain correct response selection in the face of conflicts by shielding the response selection process from response tendencies evoked by any kind of distractor.

Neuronal Intra-Individual Variability Masks Response Selection Differences between ADHD Subtypes-A Need to Change Perspectives

Due to the high intra-individual variability in attention deficit/hyperactivity disorder (ADHD), there may be considerable bias in knowledge about altered neurophysiological processes underlying executive dysfunctions in patients with different ADHD subtypes. When aiming to establish dimensional cognitive-neurophysiological constructs representing symptoms of ADHD as suggested by the initiative for Research Domain Criteria, it is crucial to consider such processes independent of variability. We examined patients with the predominantly inattentive subtype (attention deficit disorder, ADD) and the combined subtype of ADHD (ADHD-C) in a flanker task measuring conflict control. Groups were matched for task performance. Besides using classic event-related potential (ERP) techniques and source localization, neurophysiological data was also analyzed using residue iteration decomposition (RIDE) to statistically account for intra-individual variability and S-LORETA to estimate the sources of the activations. The analysis of classic ERPs related to conflict monitoring revealed no differences between patients with ADD and ADHD-C. When individual variability was accounted for, clear differences became apparent in the RIDE C-cluster (analog to the P3 ERP-component). While patients with ADD distinguished between compatible and incompatible flanker trials early on, patients with ADHD-C seemed to employ more cognitive resources overall. These differences are reflected in inferior parietal areas. The study demonstrates differences in neuronal mechanisms related to response selection processes between ADD and ADHD-C which, according to source localization, arise from the inferior parietal cortex. Importantly, these differences could only be detected when accounting for intra-individual variability. The results imply that it is very likely that differences in neurophysiological processes between ADHD subtypes are underestimated and have not been recognized because intra-individual variability in neurophysiological data has not sufficiently been taken into account.

The impact of instruction and response cost on the modulation of response-style in children with ADHD

Background

The present study investigated the impact of divergent instructions and response cost on strategic cognitive control in children with ADHD.

Methods

Children with ADHD (N = 34), combined subtype, and control children (N = 34) performed a series of self-paced computerized visual search tasks. The tasks varied by verbal instructions: after a baseline task, children were either instructed to work as fast as possible (speed instruction) or as accurately as possible (accuracy instruction). In addition, tasks were performed with and without response cost.

Results

Both groups modulated latencies and errors according to instructions in a comparable way, except for latency in the accuracy - instruction without response cost, where control children showed a larger increase of response time. Response cost did not affect the modulation of response style in children with ADHD to a larger extent than in controls. However, with instructions group differences related to target criteria became clearly more accentuated compared to baseline but disappeared when response cost was added.

Conclusions

Delay aversion theory and motivational or state regulation models may account for different aspects of the results. Modifications related to task presentation, such as the emphasis put on different details in the verbal instruction, may lead to divergent results when comparing performances of children with ADHD and control children on a self-paced task.