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Eye Vergence Responses During an Attention Task in Adults With ADHD and Clinical Controls
Abstract
Objective: ADHD patients show poor oculomotor control and recent studies show that attention-related eye vergence is weak in ADHD children. We aimed to assess vergence as a potential diagnostic biomarker for ADHD in adults. Method: We assessed the modulation in the angle of vergence while performing an attention task ( N = 144), comparing the results for adults previously diagnosed with ADHD ( N = 108) with age-matched clinical controls ( N = 36). Results: Significant differences in eye vergence response modulation between clinical controls and ADHD patients were documented. Diagnostic test accuracy was 79%. Conclusion: In combination with an attention task, eye vergence responses could be used as an objective marker to support the clinical diagnosis of adult ADHD.
... These studies have demonstrated excellent classification performance as well as the feasibility of applying machine learning to eye movement features. [36][37][38][39][40][41] A dynamic pupil size is another significant feature that can be measured using eye tracking. Studies have shown that pupil size is a promising marker for an effective examination of attentional states. ...
Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents. Traditional diagnosis methods of ADHD focus on observed behavior and reported symptoms, which may lead to a misdiagnosis. Studies have focused on computer-aided systems to improve the objectivity and accuracy of ADHD diagnosis by utilizing psychophysiological data measured from devices such as EEG and MRI. Despite their performance, their low accessibility has prevented their widespread adoption. We propose a novel ADHD prediction method based on the pupil size dynamics measured using eye tracking. Such data typically contain missing values owing to anomalies including blinking or outliers, which negatively impact the classification. We therefore applied an end-to-end deep learning model designed to impute the dynamic pupil size data and predict ADHD simultaneously. We used the recorded dataset of an experiment involving 28 children with ADHD and 22 children as a control group. Each subject conducted an eight-second visuospatial working memory task 160 times. We treated each trial as an independent data sample. The proposed model effectively imputes missing values and outperforms other models in predicting ADHD (AUC of 0.863). Thus, given its high accessibility and low cost, the proposed approach is promising for objective ADHD diagnosis.
... These so-called 'cognitive vergence' responses are associated to orienting visual attention and correlate with the late components of visual Event Related Potentials (Sole Puig et al., 2016) that reflect cognitive processing. Cognitive vergence is present in cognitive healthy persons at early developmental stages Sup er, 2018, 2019) but is atypical in patients suffering attention problems, such as ADHD (Sole Puig et al., 2015, Varela Casal et al., 2019Jim enez et al., 2020) or dyslexia (Jim enez et al., 2021). ...
Background
Facial expression of emotion is fundamental to human social interactions. Attention to relevant cues in ADHD and ASD patients are believed to underlie difficulties in recognizing emotions. Cognitive vergence eye movements during gaze fixation have a role in attention. Here we evaluate a possible role of cognitive vergence in facial emotion recognition.
Methods
We recorded eye vergence from children with ADHD (n = 27), ASD (n = 18) or ADHD&ASD (n = 15) and from neurotypical (NT; n = 31) children during a facial emotion recognition task.
Results
Vergence responses to relevant stimuli were stronger than those to distractor stimuli. ADHD and ADHD&ASD children showed shorter gaze fixation duration and weaker cognitive vergence responses to the eye regions of the face stimuli compared to neurotypically developing children. In contrast, gaze behavior and vergence responses of ASD children resembled that of neurotypically developing children.
Conclusion
These results provide evidence for the idea that impaired recognition of facial expression of emotion is a problem of attending the relevant cues to adequately recognize facial expressions. As ASD patients resembled that of NT, cognitive vergence represents an etiological difference between ADHD and ASD.
... Moreover, the onset latency and the strength of vergence responses correlate with the onset latency and strength of late EEG responses that represent visual attention (Solé Puig et al., 2016). A possible role of vergence in attention is supported by evidence showing that vergence responses predict memory Esposito & Supèr, 2019) and perception (Solé Puig, Puigcerver, & et al., 2013;, and that people with attention difficulties show poor vergence responses when performing an attention task Varela et al., 2018;Jiménez, Avella-Garcia, & et al., 2020;Jiménez, Romeo, & et al., 2020). Vergence responses are independent of the occurrence of micro-saccades (Solé Puig, Puigcerver, & et al., 2013) but there exist an interaction with pupil response and accommodation. ...
Figure-ground, that is the segmentation of visual information into objects and their surrounding backgrounds, provides structure for visual attention. Recent evidence shows a novel role of vergence eye movements in visual attention. In the present work, vergence responses during figure-ground segregation tasks are psychophysically investigated. We show that during a figure-ground detection task, subjects convergence their eyes. Vergence eye movements are larger in figure trials than in ground trials. In detected figures trials, vergence are stronger than in trials where the figure went unnoticed. Moreover in figure trials, vergence responses are stronger to low-contrast figures than to high-contrast figures. We argue that these discriminative vergence responses have a role in figure-ground.
... In addition, the scale's strength compared to other potential biomarkers of ADHD has not been established (e.g., EEG theta/beta ratio [EEG-TBR]; [65]), including those based on eye movement analysis. For example, analysis of eye vergence responses while adult participants performed an attentional task appeared to provide a somewhat stronger discriminative capacity than that found in the current study (sensitivity = 79% and specificity = 75%; [66]). This emphasizes the need for more research, both to validate the current findings and to compare the utility of eye movement measures, either alone or when combined with conventional CPT measures, to other biomarkers of ADHD. ...
Clinical decision-making may be enhanced when combining psychophysiological sensors with computerized neuropsychological tests. The current study explored the utility of integrating an eye tracker with a commercially available continuous performance test (CPT), the MOXO-dCPT. As part of the study, the performance of adult attention-deficit/hyperactivity disorder (ADHD) patients and healthy controls (n = 43, n = 42, respectively) was compared in the integrated system. More specifically, the MOXO-dCPT has four stages, which differ in their combinations of ecological visual and auditory dynamic distractors. By exploring the participants' performance in each of the stages, we were able to show that: (a) ADHD patients spend significantly more time gazing at irrelevant areas of interest (AOIs) compared to healthy controls; (b) visual distractors are particularly effective in impacting ADHD patients' eye movements, suggesting their enhanced utility in diagnostic procedures; (c) combining gaze direction data and conventional CPT indices enhances group prediction, compared to the sole use of conventional indices. Overall, the findings indicate the utility of eye tracker-integrated CPTs and their enhanced diagnostic precision. They also suggest that the use of attention-grabbing visual distractors may be a promising path for the evolution of existing CPTs by shortening their duration and enhancing diagnostic precision.
Based on previous research, there are differences between eye movements of people with attention-deficit hyperactivity disorder (ADHD) and of healthy people, as a result, the existence of differences regarding the electrooculogram (EOG) signals of the 2 groups exists. Thus, this study aimed to examine the recorded EOG signals of 30 ADHD children and 30 healthy children while performing an attention-related task. For this purpose, the EOG signals of these 2 groups were decomposed utilizing various wavelet functions. Afterward, features, including mean, energy, and standard deviation (SD) of approximation and detail wavelet coefficients were calculated. The Davies-Bouldin (DB) index was used for the evaluation of the feature space quality. Finally, the 2 groups were classified using one-dimensional feature vector and support vector machine (SVM). The SD of detail coefficients (db4) was selected as the most effective feature for separating the 2 groups. Statistical analysis revealed that the values of energy and SD of EOG signals' detail coefficients were significantly lower in the ADHD group in comparison with the healthy group (P<.001). These results showed that the speed of the ADHD group's eye movements was slower due to the fact that the high-frequency band activity of EOG signals in the healthy group was higher. In addition, the EOG signals were classified with a detection accuracy of 83.42 ± 3.8%. The results of this study can be applied in designing an EOG biofeedback protocol to treat or mitigate the symptoms of ADHD patients.
Currently, the diagnosis of attention deficit hyperactivity disorder (ADHD) is solely based on behavioral tests prescribed by the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). However, biomarkers can be more objective and accurate for diagnosis and evaluating treatment efficacy. Thus, this review aimed to identify potential biomarkers for ADHD. Search terms “ADHD,” and “biomarker” combined with one of “protein,” “blood/serum,” “gene,” and “neuro” were used to identify human and animal studies in PubMed, Ovid Medline, and Web of Science. Only papers in English were included. Potential biomarkers were categorized into radiographic, molecular, physiologic, or histologic markers. The radiographic analysis can identify specific activity changes in several brain regions in individuals with ADHD. Several molecular biomarkers in peripheral blood cells and some physiologic biomarkers were found in a small number of participants. There were no published histologic biomarkers for ADHD. Overall, most associations between ADHD and potential biomarkers were properly controlled. In conclusion, a series of biomarkers in the literature are promising as objective parameters to more accurately diagnose ADHD, especially in those with comorbidities that prevent the use of DSM-5. However, more research is needed to confirm the reliability of the biomarkers in larger cohort studies.
Atypical motor coordination and cognitive processes, such as response inhibition and working memory, have been extensively researched in individuals with attention deficit hyperactivity disorder (ADHD). Oculomotor neural circuits overlap extensively with regions involved in motor planning and cognition, therefore studies of oculomotor function may offer unique insights into motor and cognitive control in ADHD. We performed a series of pairwise meta-analyses based on data from 26 oculomotor studies in ADHD to examine whether there were differences in performance on visually-guided saccade, gap, antisaccade, memory-guided, pursuit eye movements and fixation tasks. These analyses revealed oculomotor disturbances in ADHD, particularly for difficulties relating to saccade inhibition, memorizing visual target locations and initiating antisaccades. There was no evidence for pursuit eye movement disturbances or saccade dysmetria. Investigating oculomotor abnormalities in ADHD may provide insight into top-down cognitive control processes and motor control, and may serve as a promising biomarker in ADHD research and clinical practice.
Background:
Alzheimer's disease (AD) is characterized by progressive deterioration of cognitive functions and may be preceded by mild cognitive impairment (MCI). Evidence shows changes in pupil and vergence responses related to cognitive processing of visual information.
Objective:
Here we test the hypothesis that MCI and AD are associated with specific patterns in vergence and pupil responses.
Methods:
We employed a visual oddball task. In the distractor condition (80%of the trials), a blue stimulus was presented whereas in the target condition (20%of trials) it was red. Participants (23 Controls, 33 MCI patients, and 18 AD patients) were instructed to press a button when a target appeared.
Results:
Participants briefly converged their eyes 200 ms after stimulus presentation. In controls, this transient peak response was followed by a delay response to targets but not to distractor stimuli. In the patient groups, delay responses to distractors were noticed. Consequently, the differential vergence response was strong in the control group, weak in the MCI group, and absent in the AD group. Pupils started to dilate 500-600 ms after the appearance of a target but slightly contracted after the presentation of a distractor. This differential pupil response was strongest in the AD group.
Conclusion:
Our findings support the idea of a role of vergence and pupil responses in attention and reveal altered responses in MCI and AD patients. Further studies should assess the value of vergence and pupil measurements as an objective support tool for early diagnosis of AD.
Previous research has shown that eye movements are affected by attention and can be used for the examination of attention-related disorders. In the present study, the eye movements of ADHD individuals and healthy individuals were analyzed. For this purpose, EOG signals of 30 healthy children and 30 children with ADHD were decomposed using wavelet transform (WT) while performing an attention-related task. Then the approximation and detail wavelet coefficients features such as energy and standard deviation were calculated, and the differences between the two groups were detected using statistical tests. The results showed that the energy and standard deviation of the EOG signals’ detail coefficients in ADHD children were significantly lower (P<0.001). Therefore, possibly the high-frequency band activity of EOG signals was higher in healthy children in comparison with ADHD children. The results of this study are likely to be practical in designing an EOG biofeedback protocol for treating or reducing the symptoms of ADHD disorder.
Vergence eye movements are movements of both eyes in opposite directions. Vergence is known to have a role in binocular vision. However recent studies link vergence eye movements also to attention and attention disorders. As attention may be involved in dyslexia, it is sensible to guess that the presence of reading difficulties can be associated with specific patterns in vergence responses. Data from school children performing a word-reading task have been analysed. In the task, children had to distinguish words from non-words (scrambled words or row of X’s), while their eye positions were recorded. Our findings show that after stimulus presentation eyes briefly converge. These vergence responses depend on the stimulus type and age of the child, and are different for children with reading difficulties. Our findings support the idea of a role of attention in word reading and offer an explanation of altered attention in dyslexia.
Eye vergence is the slow movement of both eyes in opposite directions enabling binocular vision. Recently, it was suggested that vergence could be involved in orienting visual attention and memory having a role in cognitive processing of sensory information. In the present study, we assessed whether such vergence responses are observed in early childhood. We measured eye vergence responses in 43 children (12–37 months of age) while looking at novel and repeated object images. Based on previous research, we hypothesized that visual attention and Visual Short-Term Memory (VSMT) would be evidenced by differential vergence responses for both experimental conditions, i.e. repeated (familiar) vs. novel items. The results show that attention related vergence is present in early childhood and that responses to repeated images differ from the ones to novel items. Our current findings suggest that vergence mechanisms could be linking visual attention with short-term memory recognition.
Attention-Deficit/Hyperactivity Disorder (ADHD) is a common childhood behavioural disorder – systematic reviews indicate that the community prevalence of ADHD globally is between 2% to 7%, with an average of around 5%. In addition, a further 5% of children have significant difficulties with over-activity, inattention and impulsivity that are just sub-threshold to meet full diagnostic criteria for ADHD. Estimates of the administrative (clinically diagnosed and/or recorded) prevalence vary worldwide and although increasing over time, ADHD is still relatively under-recognised and under-diagnosed in most countries, particularly in girls and older children. ADHD often persists into adulthood and is a risk factor for other mental health disorders and negative outcomes including educational under-achievement, difficulties with employment and relationships, and criminality. The timely recognition and treatment of children with ADHD-type difficulties provides an opportunity to improve their long-term outcomes. This review includes a systematic review of the community and administrative prevalence of ADHD in children and adolescents; an overview of the barriers to accessing care for ADHD; a description of costs associated with ADHD; and a broad discussion of evidence-based pathways for the delivery of clinical care, including a focus on key issues for two specific age groups - pre-school children and adolescents requiring transition of care from child to adult services.
Attention deficit and hyperactivity disorder (ADHD) is a prevalent childhood disorder that is often maintained throughout the development and persists into adulthood. Established etiology models suggest that deficient inhibition underlies the core ADHD symptoms. While experimental evidence for impaired motor inhibition is overwhelming, little is known about the sensory inhibition processes, their changes throughout the development, and the relationship to ADHD symptoms. Here, we used the well-established binocular rivalry (BR) paradigm to investigate for the very first time the inhibitory processes related to visual perception in adults with ADHD. In BR, perception alternates between two dichoptically presented images throughout the viewing period, with shorter dominant percept durations and longer transition periods indicating poorer suppression/inhibition. Healthy controls (N = 28) and patients with ADHD (N = 32) were presented with two dissimilar images (orthogonal gratings) separately to each eye through a mirror stereoscope and asked to report their perceptual experiences. There were no differences between groups in any of the BR markers. However, an association between transition durations and symptom severity emerged in the ADHD group. Importantly, an exploratory multiple regression analysis revealed that inattention symptoms were the sole predictor for the duration of transition periods. The lack of impairments to sensory inhibition in adult, but not pediatric ADHD may reflect compensatory changes associated with development, while a correlation between inhibition and inattention symptoms may reveal an invariant core of the disorder.
Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention is conveyed by cortical feedback connections from frontal regions to lower sensory areas modulating late stimulus responses. A recent study reported the occurrence of small eye vergence during orienting top-down attention. Here we assessed a possible link between vergence and attention by comparing visual event related potentials (vERPs) to a cue stimulus that induced attention to shift towards the target location to the vERPs to a no-cue stimulus that did not trigger orienting attention. The results rep-licate the findings of eye vergence responses during orienting attention and show that the strength and time of eye vergence coincide with the onset and strength of the vERPs when subjects oriented attention. Our findings therefore support the idea that eye vergence relates to and possibly has a role in attentional selection.
Objective:
To increase awareness of adult attention-deficit/hyperactivity disorder (ADHD) in the primary care community and to provide guidance for the management of this condition. Despite its increasing prevalence, adult ADHD largely remains underdiagnosed and inappropriately treated in the United States. The publication of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), has provided more clear diagnostic criteria for adult ADHD, but a solid framework supporting the transition of ADHD management from pediatric to adult primary care is lacking.
Data sources:
We searched PubMed and MEDLINE databases (January 1, 1984-June 1, 2016) using combinations of keywords, including ADHD, adult, diagnosis, prevalence, symptoms, treatment, comorbidity, compliance, and guidelines; international treatment guidelines; and the Diagnostic Interview for Adult ADHD websites to identify relevant clinical studies, reviews, meta-analyses, guidelines, and web-based resources describing updates to the DSM.
Study selection/data extraction:
In total, 143 citations were selected based on their relevance to adult ADHD diagnosis, treatment, major issues, and practice guidelines.
Results:
The update on diagnostic criteria in the DSM-5 may increase the diagnosis of adult ADHD. There are critical differences between childhood and adult ADHD, and specific considerations should be taken with an adult ADHD diagnosis. Adult ADHD is primarily treated with pharmacotherapy assisted by behavior interventions. Caution should be exercised when using stimulants during pregnancy and the postpartum period. Adult ADHD patients often suffer from unemployment, financial difficulties, and an unsuccessful personal life. Adult-specific guidelines may improve adult ADHD treatment.
Conclusions:
The successful diagnosis and management of adult ADHD require consideration of many facets including prior medical history and comorbid conditions and use of an individualized, evidence-based treatment approach.
The adult form of attention-deficit/hyperactivity disorder has a prevalence of up to 5% and is the most severe long-term outcome of this common disorder. Family studies in clinical samples as well as twin studies suggest a familial liability and consequently different genes were investigated in association studies. Pharmacotherapy with methylphenidate (MPH) seems to be the first-line treatment of choice in adults with attention-deficit hyperactive disorder (ADHD) and some studies were conducted on the genes influencing the response to this drug. Finally some peripheral biomarkers were identified in ADHD adult patients. We believe this work is the first systematic review and meta-analysis of candidate gene association studies, pharmacogenetic and biochemical (metabolomics) studies performed in adults with ADHD to identify potential genetic, predictive and peripheral markers linked specifically to ADHD in adults. After screening 5129 records, we selected 87 studies of which 61 were available for candidate gene association studies, 5 for pharmacogenetics and 21 for biochemical studies. Of these, 15 genetic, 2 pharmacogenetic and 6 biochemical studies were included in the meta-analyses. We obtained an association between adult ADHD and the gene BAIAP2 (brain-specific angiogenesis inhibitor 1-associated protein 2), even after Bonferroni correction, with any heterogeneity in effect size and no publication bias. If we did not apply the Bonferroni correction, a trend was found for the carriers allele 9R of dopamine transporter SLC6A3 40 bp variable tandem repeat polymorphism (VNTR) and for 6/6 homozygotes of SLC6A3 30 bp VNTR. Negative results were obtained for the 9-6 haplotype, the dopamine receptor DRD4 48 bp VNTR, and the enzyme COMT SNP rs4680. Concerning pharmacogenetic studies, no association was found for the SLC6A3 40 bp and response to MPH with only two studies selected. For the metabolomics studies, no differences between ADHD adults and controls were found for salivary cortisol, whereas lower serum docosahexaenoic acid (DHA) levels were found in ADHD adults. This last association was significant even after Bonferroni correction and in absence of heterogeneity. Other polyunsaturated fatty acids (PUFAs) such as AA (arachidonic acid), EPA (eicosapentaenoic acid) and DyLA (dihomogammalinolenic acid) levels were not different between patients and controls. No publication biases were observed for these markers. Genes linked to dopaminergic, serotoninergic and noradrenergic signaling, metabolism (DBH, TPH1, TPH2, DDC, MAOA, MAOB, BCHE and TH), neurodevelopment (BDNF and others), the SNARE system and other forty genes/proteins related to different pathways were not meta-analyzed due to insufficient data. In conclusion, we found that there were not enough genetic, pharmacogenetic and biochemical studies of ADHD in adults and that more investigations are needed. Moreover we confirmed a significant role of BAIAP2 and DHA in the etiology of ADHD exclusively in adults. Future research should be focused on the replication of these findings and to assess their specificity for ADHD.Molecular Psychiatry advance online publication, 24 May 2016; doi:10.1038/mp.2016.74.
Attention-deficit/hyperactivity disorder (ADHD) is traditionally conceptualized as a neurodevelopmental disorder that continues into adulthood in up to half of diagnosed cases. In light of current evidence, factors associated with the course of the disorder remain unknown. We performed a systematic review of the literature searching for risk markers from childhood that predicted the persistence of ADHD into adulthood. We reviewed 26,168 abstracts and selected 72 for full-text review. We identified data from 16 studies, comprising 6 population-based retrospective samples and 10 clinical follow-ups. We performed meta-analyses of factors evaluated by at least three studies. Severity of ADHD (OR 2.33, 95 % CI = 1.6-3.39, p < 0.001), treatment for ADHD (OR 2.09, 95 % CI = 1.04-4.18, p = 0.037), comorbid conduct disorder (OR 1.85, 95 % CI = 1.06-3.24, p = 0.030), and comorbid major depressive disorder (OR 1.8, 95 % CI = 1.1-2.95, p = 0.019) emerged as predictors already presented in childhood for ADHD persistence into adulthood. Further, we suggest that cohort studies should be designed to clarify such an important question for research and clinical practice.
Convergence insufficiency (CI) is a prevalent binocular vision disorder with symptoms that include double/blurred vision, eyestrain, and headaches when engaged in reading or other near work. Randomized clinical trials support that Office-Based Vergence and Accommodative Therapy with home reinforcement leads to a sustained reduction in patient symptoms. However, the underlying neurophysiological basis for treatment is unknown. Functional activity and vergence eye movements were quantified from seven binocularly normal controls (BNC) and four CI patients before and after 18 h of vergence training. An fMRI conventional block design of sustained fixation vs. vergence eye movements stimulated activity in the frontal eye fields (FEF), the posterior parietal cortex (PPC), and the cerebellar vermis (CV). Comparing the CI patients' baseline measurements to the post-vergence training data sets with a paired t-test revealed the following: (1) the percent change in the BOLD signal in the FEF, PPC, and CV significantly increased (p < 0.02), (2) the peak velocity from 4° symmetrical convergence step responses increased (p < 0.01) and (3) patient symptoms assessed using the CI Symptom Survey (CISS) improved (p < 0.05). CI patient measurements after vergence training were more similar to levels observed within BNC. A regression analysis revealed the peak velocity from BNC and CI subjects before and after vergence training was significantly correlated to the percent BOLD signal change within the FEF, PPC, and CV (r = 0.6; p < 0.05). Results have clinical implications for understanding the behavioral and neurophysiological changes after vergence training in patients with CI, which may lead to the sustained reduction in visual symptoms.
Attention Deficit Hyperactivity Disorder (ADHD) occurs in approximately 5% of the adult population and includes cardinal symptoms of hyperactivity, inattention, and impulsivity that may be difficult to identify with clinical routine methods. Continuous performance tests are objective measures of inattention and impulsivity that, combined with objective measures of motor activity, facilitate identification of ADHD among adults. The aim of the present study was to examine the sensitivity, specificity, and a composite measure of ADHD using objective measures of the ADHD-cardinal symptoms in adult participants with ADHD and non-ADHD normative participants. Cardinal symptoms were measured in 55 participants having ADHD, 202 non-ADHD normative participants, as well as 84 ADHD normative participants using the Quantified Behavior Test Plus. This test measures inattention and impulsivity using a continuous performance test, and hyperactivity using a motion-tracking system. A predictive variable for the detection of ADHD called Prediction of ADHD yielded 86% sensitivity and 83% specificity. A composite measure of ADHD cardinal symptoms was developed using a Weighed Core Symptoms scale that indicated the total amount of ADHD symptoms on a numeric scale from 0 to 100. The total amount of ADHD symptoms was measured on a scale and predicted with the categorical variable in a majority of the cases in the present study. Further studies are needed in order to confirm the results with regard to additional clinical and normative samples. Careful consideration of potential sex and diagnostic subtype differences are noteworthy aspects for future examinations of the new instruments.
Psychiatric "nosology" is largely based on clinical phenomenology using convention-based diagnostic systems not necessarily reflecting neurobiological pathomechanisms. While progress has been made regarding its molecular biology and neuropathology, the phenotypic characterization of ADHD has not improved. Thus, validated biomarkers, more directly linked to the underlying pathology, could constitute an objective measure for the condition.
The task force on biological markers of the World Federation of Societies of Biological Psychiatry (WFSBP) and the World Federation of ADHD commissioned this paper to develop a consensus report on potential biomarkers of ADHD. The criteria for biomarker-candidate evaluation were: (1) sensitivity >80%, (2) specificity >80%, (3) the candidate is reliable, reproducible, inexpensive, non-invasive, easy to use, and (4) confirmed by at least two independent studies in peer-reviewed journals conducted by qualified investigators.
No reliable ADHD biomarker has been described to date, but some promising candidates (e.g., olfactory sensitivity, substantial echogenicity) exist. A problem in the development of ADHD markers is sample heterogeneity due to aetiological and phenotypic complexity and age-dependent co-morbidities.
Most likely, no single ADHD biomarker can be identified. However, the use of a combination of markers may help to reduce heterogeneity and to identify homogeneous subtypes of ADHD.
1. A functional class of neurons in area LIP on the lateral bank of the intraparietal sulcus were shown previously (Gnadt and Andersen 1988) to be related to the metrics of saccadic eye movements. In this study, we tested LIP neurons at different depths with respect to the plane of fixation. 2. Sixty-one neurons were identified for their increased activity before saccadic eye movements. While holding the location of the target constant at the center of the frontoparallel (saccadic) response field, the neurons were tested systematically during eye movements to target positions proximal (near) to the plane of fixation, at the plane of fixation, and distal (far) to the plane of fixation. By necessity, the movements of these targets required a combination of saccadic and vergence movements. 3. Seventy-two percent of the neurons were found to change their activity as a function of target depth relative to the plane of fixation. The neurons had broad tuning curves for depth. Some cells preferred "near" target positions, some preferred "far" positions, and others responded best in the frontoparallel plane of fixation. 4. The location of a neuron's response field in the frontoparallel plane remained constant regardless of target depth. However, the magnitude of the neuron's response increased when the target was positioned at the preferred depth and it decreased for targets positioned at nonpreferred depths. This indicated that the neurons always were related to the same frontoparallel coordinates, but responded more vigorously when the target was positioned at its preferred depth. 5. The visual display apparatus allowed independent presentation of two stimulus cues for depth: binocular disparity and accommodative demand whereas other cues were held constant. For many neurons, either cue was sufficient to tune the activity in depth, though most neurons responded best for the geometrically appropriate combination of the two cues. 6. Comparison of the binocular tuning for depth with the individual monocular responses showed that the tuning for depth was not produced by simple linear combination of two monocular response fields. 7. We tested a subset of the neurons in a double-movement task that dissociated the retinal coordinates of the visual stimuli from the eye-movement coordinates of the second movement. These tests confirmed earlier findings that this functional class of neurons are active when the eye-movement coordinates matched the neurons' response field. It was not necessary for a visual stimulus to fall within the neurons' response field for them to become active.(ABSTRACT TRUNCATED AT 400 WORDS)
The worldwide prevalence estimates of attention deficit hyperactivity disorder (ADHD)/hyperkinetic disorder (HD) are highly heterogeneous. Presently, the reasons for this discrepancy remain poorly understood. The purpose of this study was to determine the possible causes of the varied worldwide estimates of the disorder and to compute its worldwide-pooled prevalence.
The authors searched MEDLINE and PsycINFO databases from January 1978 to December 2005 and reviewed textbooks and reference lists of the studies selected. Authors of relevant articles from North America, South America, Europe, Africa, Asia, Oceania, and the Middle East and ADHD/HD experts were contacted. Surveys were included if they reported point prevalence of ADHD/HD for subjects 18 years of age or younger from the general population or schools according to DSM or ICD criteria.
The literature search generated 9,105 records, and 303 full-text articles were reviewed. One hundred and two studies comprising 171,756 subjects from all world regions were included. The ADHD/HD worldwide-pooled prevalence was 5.29%. This estimate was associated with significant variability. In the multivariate metaregression model, diagnostic criteria, source of information, requirement of impairment for diagnosis, and geographic origin of the studies were significantly associated with ADHD/HD prevalence rates. Geographic location was associated with significant variability only between estimates from North America and both Africa and the Middle East. No significant differences were found between Europe and North America.
Our findings suggest that geographic location plays a limited role in the reasons for the large variability of ADHD/HD prevalence estimates worldwide. Instead, this variability seems to be explained primarily by the methodological characteristics of studies.
According to the DSM-IV TR, approximately 3 to 7% of school-age children meet the criteria for ADHD. However, there is a common conception that ADHD is overdiagnosed. The purpose of this article is to evaluate the evidence for and against overdiagnosis.
Recent prevalence studies and research on factors affecting diagnostic accuracy were reviewed. For ADHD to be overdiagnosed, the rate of false positives (i.e., children inappropriately diagnosed with ADHD) must substantially exceed the number of false negatives (children with ADHD who are not identified or diagnosed).
Based on the review of prevalence studies and research on the diagnostic process, there does not appear to be sufficient justification for the conclusion that ADHD is systematically overdiagnosed. Yet, this conclusion is generally not reflected in public perceptions or media coverage of ADHD. Potential explanations for the persistence of the belief in the overdiagnosis of ADHD are offered.
Objective:
ADHD youth show poor oculomotor control. Recent research shows that attention-related eye vergence is weak in ADHD children.
Method:
To validate vergence as a marker to classify ADHD, we assessed the modulation in the angle of vergence of children ( n = 43) previously diagnosed with ADHD while performing an attention task and compared the results with age-matched clinical controls ( n = 19) and healthy peers ( n = 30).
Results:
We observed strong vergence responses in healthy participants and weak vergence in the clinical controls. ADHD children showed no significant vergence responses. Machine-learning models classified ADHD patients ( n = 21) from healthy controls ( n = 21) with an accuracy of 96.3% (false positive [FP]: 5.12%; false negative [FN]: 0%; area under the curve [AUC]: 0.99) and ADHD children ( n = 11) from clinical controls ( n = 14) with an accuracy of 85.7% (FP: 4.5%; FN: 19.2%, AUC: 0.90).
Conclusion:
In combination with an attention task, vergence responses can be used as an objective marker to detect ADHD in children.
In line with a possible role of vergence in orienting visual attention, we sought to study this eye movement in young children to provide insights on face perception. For this purpose, we measured the modulation in the angle of eye vergence in a sample of 39 children aged 6-36 months and compared it when presenting static human face images versus their scrambled version. We observed enhanced vergence responses to faces compared with scrambled images. Our data suggest a role of eye vergence in face processing.
The prevalence of attention deficit hyperactivity disorder is about 5% of the child population, and it carries risks for mental health, educational and personal dysfunction, antisociality and death. The diagnosis in practice is made with remarkable differences in frequency between nations. Low rates in the UK, by comparison with research estimates, suggest that the condition may often be missed in clinical practice; the reasons are considered. © 2016 BMJ Publishing Group Ltd & Royal College of Paediatrics and Child Health.
This study examines the relationship between self-reported ADHD and adult mortality over a four-year period, and whether ADHD is associated with underlying cause of death (accidents versus all others). If ADHD increases mortality risk through accidents, then interventions may be designed and implemented to reduce risk and prevent premature death. We estimate descriptive statistics and multivariate logistic regression models using data from the 2007 U.S. National Health Interview Survey (NHIS) Sample Adult File linked to National Death Index (NDI) data through 2011 (N = 23.352). Analyses are weighted and standard errors are adjusted for the complex sampling design. We find that the odds of dying are significantly higher among those with ADHD than among those without ADHD net of exogenous sociodemographic controls (adjusted odds ratio = 1.85; 95% confidence interval = 1.06, 3.23). Although marginally non-significant, accidental death is more common among those with ADHD than among those without ADHD (13.2% versus 4.3%, p = 0.052). Few population-representative studies examine the relationship between ADHD and adult mortality due to data limitations. Using NHIS data linked to the NDI, we are only able to observe a few deaths among adults with ADHD. However, ADHD is associated with a significantly higher odds of dying for adults and results suggest that accidents may be an underlying cause of death more often for decedents with ADHD. Future research should further examine the mechanisms linking ADHD to adult mortality and the extent to which mortality among persons with ADHD is preventable. Regular measurement of ADHD among adults in the NHIS is warranted.
Objective:
The aim of this study was to assess for the first time the criterion validity of the semi-structured Diagnostic Interview for ADHD in adults (DIVA 2.0), and its concurrent validity in comparison with the Conners' Adult ADHD Diagnostic Interview for DSM-IV (CAADID) and other ADHD severity scales, following the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria.
Method:
A transversal study was performed on 40 out-patients with ADHD to check the criteria and concurrent validity of the DIVA 2.0 compared with the CAADID.
Results:
The DIVA 2.0 interview showed a diagnostic accuracy of 100% when compared with the diagnoses obtained with the CAADID interview. The concurrent validity demonstrated good correlations with three self-reported rating scales: the Wender Utah Rating Scale (WURS; r = .544, p < .0001), the ADHD-Rating Scale (r = .720, p < .0001), and Sheehan's Dysfunction Inventory (r = .674, p < .0001).
Conclusion:
The DIVA 2.0 is a reliable tool for assessing and diagnosing Adult ADHD and is the only one that offers free online access for clinical and research purposes.
Objectives:
Until recently, it was believed that attention deficit and hyperactivity disorder (ADHD) are outgrown by the end of adolescence and the beginning of adulthood. The purpose of this review is to describe the characteristics of the disease in adults, depict comorbidities that accompany it, and expand the scope over methods of diagnosis and treatment of these ages.
Methods:
A search was conducted in the PubMed/MEDLINE database for relevant key words 'ADHD', 'attention deficit', 'hyperactivity' and 'adult'. Secondary search parameters were 'comorbid', 'prevalence', 'epidemiology', 'therapy' and 'drug therapy'. Search was limited to 'English' and 'Humans'.
Results:
Over the years, the persistent nature of the disorder has been clarified, elucidating prevalence rate, gender differences and subtype shifts among adult ADHD population. Nevertheless, even today, there is only limited awareness of the existence of the disorder across one's lifespan, its consequences and the appropriate treatment.
Conclusions:
Our results emphasise the growing awareness of adult psychosocial impairments due to ADHD symptoms and comorbidities, as well as the need for further collaboration among practitioners and mental health-care professionals to better identify the condition and allow for effective treatment.
Objective:
Patients with adult attention-deficit/ hyperactivity disorder (ADHD) and bipolar disorder can present with similar symptoms, including increased energy, distractibility, disorganization, impulsivity, hyperactivity, and rapid speech. Determining whether the patient has either, or possibly both, of these syndromes can be a complex task. This review attempts to clarify where these disorders overlap, both symptomatically and epidemiologically, and where they diverge, to help clinicians increase the accuracy of their diagnoses. Changes to diagnostic criteria from the fourth to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (from DSM-IV-TR to DSM-5) are discussed, as is the evidence base for pharmacological treatments.
Method:
Studies and sources were identified using computerized searches.
Results:
Adult ADHD and bipolar disorder have multiple overlapping symptoms, but there are differences in prevalence (ADHD affects 4.4% of adults in the United States versus 1.4% for bipolar disorder), onset of symptoms (usually before age 7 years in ADHD versus after age 12 years in bipolar disorder), disease course (chronic in ADHD versus cyclical in bipolar disorder), mood symptoms (absent in ADHD but always present in bipolar disorder), and psychotic symptoms (absent in ADHD but sometimes present in bipolar disorder). Approximately 20% of adult patients with ADHD also have bipolar disorder, while 10%-20% of patients with bipolar disorder have adult ADHD. Comorbidity of bipolar disorder and ADHD is associated with an earlier age of onset and a more chronic and disabling course of bipolar disorder, as well as more psychiatric comorbidity.
Conclusion:
Distinguishing between adult ADHD and bipolar disorder requires careful attention to phenomenology and awareness of epidemiology, with a focus on childhood history, lifetime course of symptoms, and the possibility of comorbidity.
The association between attention-deficit hyperactivity disorder (ADHD) and criminality has been increasingly recognized as an important societal concern. Studies conducted in different settings have revealed high rates of ADHD among adolescent offenders. The risk for criminal behavior among individuals with ADHD is increased when there is psychiatric comorbidity, particularly conduct disorder and substance use disorder. In the present report, it is aimed to systematically review the literature on the epidemiological, neurobiological, and other risk factors contributing to this association, as well as the key aspects of the assessment, diagnosis, and treatment of ADHD among offenders. A systematic literature search of electronic databases (PubMed, EMBASE, and PsycINFO) was conducted to identify potentially relevant studies published in English, in peer-reviewed journals. Studies conducted in various settings within the judicial system and in many different countries suggest that the rate of adolescent and adult inmates with ADHD far exceeds that reported in the general population; however, underdiagnosis is common. Similarly, follow-up studies of children with ADHD have revealed high rates of criminal behaviors, arrests, convictions, and imprisonment in adolescence and adulthood. Assessment of ADHD and comorbid condition requires an ongoing and careful process. When treating offenders or inmates with ADHD, who commonly present other comorbid psychiatric disorder complex, comprehensive and tailored interventions, combining pharmacological and psychosocial strategies are likely to be needed.
Neuropsychology examines the relationship between cognitive activity and corresponding cerebral conditions. At one end, psychophysics meticulously describes the details of behavior. At the other, physiology records brain cell activity during cognitive tasks. Bridging the two, neuropsychology establishes the neural correlate of behaviour when correlation methods are used, and extends to the critical neural substrate when a causal relationship can be established. Here we revisit the Hering-versus-Helmholtz controversy on binocular coordination from the psychophysician's description of combined saccade-vergence eye movements to the neurophysiological recording of motor and premotor neurons of the oculomotor neural circuitry. Whilst neo-Heringian psychophysicians and physiologists have accumulated arguments for separate saccade and vergence systems, at both the behavioral and the neural premotor levels, neo-Helmholtzians have also provided evidence for monocular programmed eye movements and commands at the premotor level. Bridging the two, we conclude that Hering and Helmholtz were both right. Importantly, the latter's viewpoint brings to the fore the importance of adaptive processes throughout life, in view of the neurobiological constraints emphasized by the former.
Background: Self-rating scales and cognitive tests are instruments used in the assessment of attention-deficit hyperactivity disorder (ADHD). However, few studies have examined the differential validity of these kinds of instruments in psychiatric samples. Aims: To examine the discriminative validity of two self-report scales (ADHD Self-Report Scale [ASRS v.1.1], Current Symptom Scale [CSS]) and a continuous performance test with measures of motor activity (QBTest Plus). Methods: The interrelation between the instruments, and their abilities to differentiate between patients with an ADHD diagnosis and non-ADHD patients referred for psychiatric assessment were examined in a naturalistic sample of 61 adult patients. Results: The area under the receiver operating characteristic curve (AUC) for the dichotomized versions of the test variables in all tests ranged from 0.61 to 0.71. The ASRS and CSS exhibited sensitivity of 90.2% and 85.4%, and specificity of 35.0% and 40.0%, respectively. Variables from the QBTest Plus showed the opposite result for the variables QBImpulsivity and QBInattention, with sensitivity of 58.5% and 36.3% and specificity of 80.0% and 100.0%. Sensitivity and specificity of QBActivity were 68.3% and 65.0%, respectively. A stepwise discriminant function analysis showed that two variables from the QBTest Plus-QBInattention and QBActivity-accounted for 22.8% of the between-group variability, with the strongest predictor being QBInattention. The function yielded an overall correct classification of 72.1%. The classification correctly identified 87.8% of patients diagnosed with ADHD and 40.0% of non-ADHD patients. Conclusion: The discriminant validity of self-rating scales and the more objective measure of ADHD symptoms are poor and should be integrated generally with other sources of data.
This article aims to review basic and clinical studies outlining the roles of prefrontal cortical (PFC) networks in the behavior and cognitive functions that are compromised in childhood neurodevelopmental disorders and how these map into the neuroimaging evidence of circuit abnormalities in these disorders.
Studies of animals, normally developing children, and patients with neurodevelopmental disorders were reviewed, with focus on neuroimaging studies.
The PFC provides "top-down" regulation of attention, inhibition/cognitive control, motivation, and emotion through connections with posterior cortical and subcortical structures. Dorsolateral and inferior PFC regulate attention and cognitive/inhibitory control, whereas orbital and ventromedial structures regulate motivation and affect. PFC circuitries are very sensitive to their neurochemical environment, and small changes in the underlying neurotransmitter systems, e.g. by medications, can produce large effects on mediated function. Neuroimaging studies of children with neurodevelopmental disorders show altered brain structure and function in distinctive circuits respecting this organization. Children with attention-deficit/hyperactivity disorder show prominent abnormalities in the inferior PFC and its connections to striatal, cerebellar, and parietal regions, whereas children with conduct disorder show alterations in the paralimbic system, comprising ventromedial, lateral orbitofrontal, and superior temporal cortices together with specific underlying limbic regions, regulating motivation and emotion control. Children with major depressive disorder show alterations in ventral orbital and limbic activity, particularly in the left hemisphere, mediating emotions. Finally, children with obsessive-compulsive disorder appear to have a dysregulation in orbito-fronto-striatal inhibitory control pathways, but also deficits in dorsolateral fronto-parietal systems of attention.
Altogether, there is a good correspondence between anatomical circuitry mediating compromised functions and patterns of brain structure and function changes in children with neuropsychiatric disorders. Medications may optimize the neurochemical environment in PFC and associated circuitries, and improve structure and function.
Visual attention is the mechanism the nervous system uses to highlight specific locations, objects or features within the visual field. This can be accomplished by making an eye movement to bring the object onto the fovea (overt attention) or by increased processing of visual information in neurons representing more peripheral regions of the visual field (covert attention). This review will examine two aspects of visual attention: the changes in neural responses within visual cortices due to the allocation of covert attention; and the neural activity in higher cortical areas involved in guiding the allocation of attention. The first section will highlight processes that occur during visual spatial attention and feature-based attention in cortical visual areas and several related models that have recently been proposed to explain this activity. The second section will focus on the parietofrontal network thought to be involved in targeting eye movements and allocating covert attention. It will describe evidence that the lateral intraparietal area, frontal eye field and superior colliculus are involved in the guidance of visual attention, and describe the priority map model, which is thought to operate in at least several of these areas.
We recorded from neurons dorsal and dorsolateral to the third nerve nucleus of the monkey whose discharge rates modulated when the monkey tracked targets moving in depth but not when it tracked targets moving from side to side. The neurons' activity modulated equally well whether the target moved directly toward one eye or the other. For most neurons the amplitude of modulation was similar whether the monkey tracked monocularly (blur cue alone), binocularly with accommodation open-loop (disparity cue alone), or in normal binocular viewing. By comparing the modulation in normal binocular viewing with that when the blur and disparity cues were in conflict we were able to show that 19 neurons discharged in relation to the vergence response alone and not to accommodation. Eight neurons discharged exclusively in relation to accommodation. While the monkeys tracked targets moving in depth so that target vergence varied with a sinusoidal time course (frequency 0.1 or 0.2 Hz) the discharge modulations of identified vergence cells generally showed much more phase lead than expected of motoneurons. We examined the activity of a subset of these vergence cells in response to a range of stimulus frequencies to compare the dynamics of these neurons with motoneurons. The phase leads were larger than those expected of motoneurons over the entire frequency range tested. We speculate that vergence neurons may selectively activate (directly or indirectly) motoneurons with longer time constants than the mean.
Animals with binocular single vision use disjunctive (vergence) eye movements to align the two eyes on a visual target. Several lines of evidence suggest that conjugate and vergence eye movement commands are generated independently and combined at the medial rectus motoneurons. If this were true, then a pure vergence eye-position signal should exist. This signal would be proportional to the horizontal angle between the eyes (vergence angle), without regard to the direction of conjugate gaze. The purpose of this experiment was to identify and study neurons that carry a pure vergence signal. Extracellular unit recordings were made from midbrain and pontine sites in monkeys trained to track visual targets moving in the horizontal, vertical, and depth (or target vergence) planes. The most commonly encountered neuron that had a vergence signal was the convergence cell. These units had a firing rate that was linearly proportional to the convergence angle; their activity was unaffected by changes in conjugate gaze. Changes in convergence cell activity preceded the change in vergence angle slightly. Convergence cell activity increased for increased convergence regardless of whether the change was in response to purely accommodative or disparity cues. Divergence cells were found far less frequently. These cells were similar to convergence cells except that they decreased their firing rate for increases in convergence. The activity of divergence cells was unaffected by changes in the direction of conjugate gaze. Both convergence and divergence cells were found, intermixed, in the mesencephalic reticular formation must outside the oculomotor nucleus. Most cells with a vergence signal were found within 1-2 mm of the nucleus. These results support the view that conjugate and vergence signals are generated independently and are combined at the extraocular motoneurons. Convergence cells seem ideally suited to provide the vergence signal required by the nearby medial rectus motoneurons.
Recent studies have indicated that the superior colliculus (SC), traditionally considered to be saccade-related, may play a role in the coding of eye movements in both direction and depth. Similarly, it has been suggested that omnidirectional pause neurons are not only involved in the initiation of saccades, but can also modulate vergence eye movements. These new developments provide a challenge for current oculomotor models that attempt to describe saccade-vergence coordination and the neural mechanisms that may be involved. In this paper, we have attempted to study these aspects further by investigating the role of the rostral pole of the SC in the control of vergence eye movements. It is well-known that, by applying long-duration electrical stimulation to rostral sites in the monkey SC, saccadic responses can be prevented and interrupted. We have made use of these properties to extend this paradigm to eye movements that contain a substantial depth component. We found that electrical intervention in the rostral region also has a clear effect on vergence. For an eye movement to a near target, stimulation leads to a significant suppression and change in dynamics of the pure vergence response during the period of stimulation, but the depth component cannot be prevented entirely. When these paradigms are implemented for 3D refixations, the saccade is inactivated, as expected, while the vergence component is often suppressed more than in the case of the pure vergence. The data lead us to conclude that the rostral SC, presumably indirectly via connections with the pause neurons, can affect vergence control for both pure vergence and combined 3D responses. Suppression of the depth component is incomplete, in contrast to the directional movement, and is often different in magnitude for 3D refixations and pure vergence responses. The results are discussed in connection with current models for saccade-vergence interaction.
To view objects at different distances, humans rely on vergence eye movements to appropriately converge or diverge the eyes and on ocular accommodation to focus the object. Despite the importance of these coordinated eye movements (the 'near response') very little is known about the role of the cerebral cortex in their control. As near-response neurons exist within the nucleus reticularis tegmenti pontis, which receives input from the frontal eye field region of frontal cortex, and this cortical region is known to be involved in saccadic and smooth-pursuit eye movements, we propose that a nearby region might play a role in vergence and ocular accommodation. Here we provide evidence from rhesus monkeys that a region of frontal cortex located immediately anterior to the saccade-related frontal eye field region is involved in vergence and ocular accommodation, and in the sensorimotor transformations required for these eye movements. We conclude that the macaque frontal cortex is involved in the control of all voluntary eye movements, and suggest that the definition of the frontal eye fields should be expanded to include this region.
Our recent studies in non-human primates have identified and characterized cerebro-ponto-cerebellar pathways involved in the control of vergence eye movements. Specifically, within the deep cerebellar nuclei and nucleus reticularis tegmenti pontis, we have identified neurons that are related to either the near response (convergence and increased ocular accommodation) or the far response (divergence and decreased ocular accommodation). In addition, within the prearcuate region (area 8a), we have characterized neurons related not only to either the far response or the near response, but also to the sensorimotor transformations underlying these eye movements. Because the vergence-related prearcuate region abuts the frontal eye fields, we suggest that the extent of the frontal eye fields be expanded to include this region. We further suggest that with inclusion of this vergence-related region, the frontal eye fields are important for all voluntary eye movements.
Results of our previous studies suggest that the circumscribed area in the rostral superior colliculus (SC) of the cat is involved in the control of accommodation. Accommodation is closely linked with vergence eye movements. In this study, we investigated whether or not vergence eye movements are evoked by microstimulation of the rostral SC in the cat. In addition, we studied the effect of chemical inhibition of the rostral SC on visually guided vergence eye movements. This study was conducted on three cats, weighing 2.5-3.5 kg. The animals were trained to carry out visually guided saccade and convergence tasks. Eye movements were measured using search coils placed on both eyes. We recorded eye movements evoked by microstimulation of the rostral SC in the alert cats. Muscimol was injected into the rostral SC, and the effect of SC inactivation on visually guided vergence eye movements was investigated. Convergence eye movements were evoked by low-current stimulation (< 30 microA) of a circumscribed area in the intermediate layers of the rostral SC on one side. Spontaneous saccades were interrupted by the stimulation of the low-threshold area for evoking convergence. Visually guided convergence eye movements were severely diminished by the injection of muscimol into the low-threshold area for evoking convergence of the SC. The rostral SC is related to the control of vergence eye movements as well as accommodation. The rostral SC may be involved in the functional linkage between accommodation, convergence and visual fixation.
To examine the ability of the flicker task to demonstrate greater utility in discriminating performance in young adults with and without ADHD compared to the Conners' CPT (CCPT).
Flicker task and CCPT performance were compared between an ADHD (n = 28) and control (n = 30) group of college students.
This study replicated previous flicker task findings, providing support for using the flicker task to demonstrate the robust nature of change blindness. However, the flicker task did not demonstrate better discriminative utility than the CCPT. Task-dependent measures correlated with ADHD rating scale indices of inattention and hyperactivity/impulsivity, indicating that CPTs lack symptom domain specificity.
Results support the growing evidence that CPTs currently provide only modest utility for discriminating performance in adults with and without ADHD. Recommendations are provided regarding the future study of CPTs as a valid measure of ADHD performance and the potential utility of the flicker task.
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