Improving antisaccade performance in adolescents with attention-deficit/hyperactivity disorder (ADHD)

Eye-movement indices of arousal predict ADHD and comorbid externalizing symptoms over a 2-year period

Attention-deficit/hyperactivity disorder (ADHD) follows a variable course across childhood. Disrupted arousal has been hypothesized to underlie core symptoms as well as comorbid internalizing and externalizing conditions. The current study examined eye-movement and pupil-dilation metrics indexing arousal as longitudinal predictors of ADHD, externalizing, and internalizing symptoms over a 2-year period. Participants aged 8-13 years (N = 54, 30% with a diagnosis of ADHD) completed a modified version of the gap-overlap task including arousal-inducing auditory warning signals. Parents rated symptoms at the time of testing and at 2 years follow-up. Phasic alerting (reaction-time reduction after alerting cues) is an index of arousal. Here, larger phasic alerting effects predicted higher ADHD-symptom levels 2 years later. Blunted pupil-dilation responses predicted externalizing symptoms at T2, controlling for ADHD and externalizing at T1. Our results support the theory that ADHD is associated with altered arousal. Blunted arousal reactivity may be a longitudinal risk factor for externalizing problems in children with ADHD symptoms.

The Eyes Have It: A Meta-analysis of Oculomotor Inhibition in Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Diminished inhibitory control is one of the main characteristics of attention-deficit/hyperactivity disorder (ADHD), and impairments in oculomotor inhibition have been proposed as a potential biomarker of the disorder. The present meta-analysis summarizes the effects reported in studies comparing oculomotor inhibition in ADHD patients and healthy control subjects.

METHODS

Inhibitory outcomes were derived from oculomotor experimental paradigms including the antisaccade (AS), memory-guided saccade, and prolonged fixation tasks. Temporal and spatial measures were also extracted from these tasks and from visually guided saccade tasks as secondary outcomes. Data were available from k = 31 studies (N = 1567 participants). Summary effect sizes were computed using random-effects models and a restricted maximum-likelihood estimator.

RESULTS

Among inhibitory outcomes, direction errors in AS, after correcting for publication bias, showed a moderate effect and large between-study heterogeneity (k = 18, n = 739, g = 0.57, 95% confidence interval [CI] [0.27, 0.88], I²= 74%); anticipatory saccades in memory-guided saccade showed a large effect and low heterogeneity (k = 11, n = 487; g = 0.86, 95% CI [0.64, 1.08], I² = 17.7%); and saccades during prolonged fixation evidenced large effect size and heterogeneity (k = 6, n = 325 g = 1.11, 95% CI [0.56, 1.65], I² = 79.1%) partially related to age. Among secondary outcomes, saccadic reaction time in AS (k = 22, n = 932, g = 0.34, 95% CI [0.06, 0.63], I² = 53.12%) and coefficient of variability in visually guided saccade (k = 5, n = 282, g = 0.53, 95% CI [0.28, 0.78], I² = 0.01%) indicated significant effects with small to moderate effects sizes.

CONCLUSIONS

ADHD groups commit more oculomotor inhibition failures than control groups. The substantial effects support the conclusion that oculomotor disinhibition is a relevant ADHD-related mechanism. Moderate effects observed in saccadic reaction time variability suggest that fluctuant performance in oculomotor tasks is another relevant characteristic of ADHD.

The effect of feedback in virtual attention training on orienting attention in individuals with sluggish cognitive tempo

OBJECTIVE

This study was conducted to assess the effectiveness of feedback in a virtual attention training program to improve the attentional characteristics of sluggish cognitive tempo (SCT).

METHOD

The SCT group (N = 60) and control group (N = 30) were identified, and the attention network test-revised (ANT-R) was performed to measure attention characteristics. Based on this result, a virtual reality (VR) feedback attention training program was developed to improve the efficiency of engagement and disengagement of attention in SCT. Sixty participants with SCT were recruited and grouped into two conditions: VR feedback (n = 30) and no-feedback (n = 30) conditions.

RESULTS

The results show that the VR attention training program with feedback significantly improves the attention-orienting network.

CONCLUSION

This suggests that it is necessary to provide immediate feedback for effective attention training for SCT and continuous intervention may be possible when feedback is provided together.

Visual search in neurodevelopmental disorders: evidence towards a continuum of impairment

Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses. N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.

Oculomotor deficits in attention deficit hyperactivity disorder (ADHD): A systematic review and comprehensive meta-analysis

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.

Volitional eye movement control and ADHD traits: a twin study

BACKGROUND

Top-down volitional command of eye movements may serve as a candidate endophenotype of ADHD, an important function underlying goal-directed action in everyday life. In this twin study, we examined the relation between performance on a response inhibition eye-tracking paradigm and parent-rated ADHD traits in a population-based twin sample. We hypothesized that altered eye movement control is associated with the severity of ADHD traits and that this association is attributable to genetic factors.

METHODS

A total of 640 twins (320 pairs, 50% monozygotic) aged 9-14 years) from the Child and Adolescent Twin Study in Sweden (CATSS) participated. Twins performed the antisaccade task indexing inhibitory alterations as either direction errors (following exogenous cues rather than instructions) or premature anticipatory eye movements (failure to wait for cues). We calculated the associations of eye movement control and ADHD traits using linear regression mixed-effects models and genetic and environmental influences with multivariate twin models.

RESULTS

Premature anticipatory eye movements were positively associated with inattentive traits (β = .17; 95% CI: 0.04, 0.31), while controlling for hyperactive behaviors and other covariates. Both premature anticipatory eye movements and inattention were heritable (h²  = 0.40, 95% CI: 0.22, 0.56; h²  = 0.55; 95% CI: 0.42, 0.65; respectively), and their genetic correlation was small but statistically significant (r = .19, 95% CI: 0.02, 0.36). However, the genetic correlation did not remain significant after adjusting for covariates (age, sex, hyperactivity traits, IQ). No link was found between direction errors and ADHD traits.

CONCLUSIONS

This study indicates that there is a specific, genetically influenced, relation between top-down eye movement control and the inattentive traits typical of ADHD.

The Effect of Eye-Feedback Training on Orienting Attention in Young Adults With Sluggish Cognitive Tempo

Sluggish cognitive tempo (SCT) is a kind of attentional symptoms characterized by symptoms of slowness in behavior or in thinking. The aim of the present study was to develop a preliminary attention training program based on real-time eye-gaze feedback using an eye-tracker. A total of 38 participants with SCT were randomly assigned to one of following two conditions: eye-feedback (N = 19; Mean Age = 21.21; range 18-26) or control (N = 19; Mean Age = 20.68; range 18-25). The participants in the eye-feedback condition received three repeated trainings on the modified version of the Posner's spatial cueing test; we also used real-time constant eye-gaze feedback designed to lead the participants to quickly and accurately engage and to disengage, with pre- and post- measurement of eye-movements (overt attention) and the revised attention network test (ANT-R; covert attention). The participants in the control condition received three repeated same trainings without any feedback, with pre- and post-measurement of eye-movements measure and ANT-R. The results revealed that the eye-feedback group showed a greater improvement in engaging and disengaging attention through the overt attention measure than the control group. The eye-feedback group also showed a greater increase only in the orienting network related to disengaging attention in the covert attention measure compared to the control group. These results suggested that the eye-feedback can be meaningfully used in attention training to enhance the efficiency of attention in clinical settings.

Anti-saccades predict cognitive functions in older adults and patients with Parkinson's disease

A major component of cognitive control is the ability to act flexibly in the environment by either behaving automatically or inhibiting an automatic behaviour. The interleaved pro/anti-saccade task measures cognitive control because the task relies on one's abilities to switch flexibly between pro and anti-saccades, and inhibit automatic saccades during anti-saccade trials. Decline in cognitive control occurs during aging or neurological illnesses such as Parkinson's disease (PD), and indicates decline in other cognitive abilities, such as memory. However, little is known about the relationship between cognitive control and other cognitive processes. Here we investigated whether anti-saccade performance can predict decision-making, visual memory, and pop-out and serial visual search performance. We tested 34 younger adults, 22 older adults, and 20 PD patients on four tasks: an interleaved pro/anti-saccade, a spatial visual memory, a decision-making and two types of visual search (pop-out and serial) tasks. Anti-saccade performance was a good predictor of decision-making and visual memory abilities for both older adults and PD patients, while it predicted visual search performance to a larger extent in PD patients. Our results thus demonstrate the suitability of the interleaved pro/anti-saccade task as a cognitive marker of cognitive control in aging and PD populations.

Educational and Cognitive Predictors of Pro- and Antisaccadic Performance

Voluntary gaze control allows people to direct their attention toward selected targets while avoiding distractors. Failure in this ability could be related to dysfunctions in the neural circuits underlying executive functions. Interestingly, recent evidence suggests that factors such as years of schooling and literacy may positively influence goal-directed behavior and inhibitory control. However, we do not yet know whether these factors also have a significant impact on the inhibitory control of oculomotor responses. Using pro- and antisaccadic tasks to assess the behavioral responses of healthy adults, we tested the contribution of years of schooling and reading proficiency to their oculomotor control, while simultaneously analyzing the effects of other individual characteristics related to demographic, cognitive and motor profiles. This approach allowed us to test the hypothesis that schooling factors are closely related to oculomotor performance. Indeed, a regression analysis revealed important contributions of reading speed and intellectual functioning to the choices on both pro- and antisaccadic tasks, while years of schooling, age and block sequence emerged as important predictors of the kinematic properties of eye movements on antisaccadic tasks. Thus, our findings show that years of schooling and reading speed had a strong predictive influence on the oculomotor measures, although age and order of presentation also influenced saccadic performance, as previously reported. Unexpectedly, we found that an indirect measure of intellectual ability also proved to be a good predictor of the control of saccadic movements. The methods and findings of this study will be useful for identifying and breaking down the cognitive and educational components involved in assessing voluntary and automatic responses.

The Efficacy of Computerized Cognitive Training in Adults With ADHD: A Randomized Controlled Trial

OBJECTIVE

This is a randomized control trial examining the efficiency of computerized cognitive training (CCT) for adults with ADHD, comparing two training conditions with graded levels of executive cognitive demands.

METHOD

Adults with ADHD (n = 60) were randomized into study (n = 34) and control (n = 26) groups. Training was conducted with the computerized AttenFocus program. Control group received a simple, non-hierarchical version with less executive demands.

RESULTS

Significant positive changes in symptoms ratings, ecological measures of executive functions, and occupational performance were found in both groups. No significant changes were found in variables of neurocognitive performance battery and quality of life. No significant time by group interaction effects were found.

CONCLUSION

No benefits of the intervention were found relative to the control. Lack of interaction effects may be due to insufficient power, non-specific cognitive training or placebo effects. Results demonstrate some positive findings for general CCT, yet do not support the inclusion of specific higher level executive training.

Inattention, Working Memory, and Goal Neglect in a Community Sample

Executive function deficits have been linked to attention deficit hyperactivity disorder (ADHD), but it has been theorized that the symptom inattention is specifically related to problems with complex verbal working memory (WM). Using the Conners Adult ADHD rating scale, adults aged 18–35 were assessed for ADHD symptoms, and completed tasks designed to tap verbal and spatial aspects of WM (Experiment 1). Results showed that high inattention predicted poor performance on both simple and complex verbal WM measures. Results relating to spatial WM were inconclusive. In a follow up experiment based on the theory that those with inattention have problems receiving verbal instructions, a measure of goal neglect assessing integration of information into a task model in WM was employed (Experiment 2). Results showed that high inattention uniquely predicted performance on this task, representing the first reported association between inattention and the phenomenon of goal neglect. The results from both experiments lend support to the WM theory of inattention.

Usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder/hyperkinetic disorder in adults

Background:

The aim of the research is to evaluate the usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder (ADHD)/hyperkinetic disorder (HKD) in adults.

Methods:

Seventy-eight individuals were examined: 40 with ADHD/HKD and 38 healthy ones. A noninvasive eye movement examination using the Saccadometer (Advanced Clinical Instrumentation, Cambridge, UK) was applied. Two saccadic tests, prosaccades task (PT) and antisaccades task (AT), were carried out.

Results:

Based on the results, we can assume that selected parameters, such as latency, standard deviation of latency, promptness, and correctness (directional errors), in individuals with ADHD/HKD differ statistically in the relevant parameters from the healthy ones. The latency and the standard deviation of latency in ADHD/HKD participants are greater when compared to healthy ones. ADHD/HKD participants have a greater number of directional errors in comparison to healthy ones.

Conclusions:

The standard deviation of latency prosaccades is a good parameter for distinguishing people from both groups. An important and innovative solution in this study in comparison to the studies of other authors, who reached similar results, is the use of an automatically calibrating system (autonomous) adapted for clinical use as well as a quantitative analysis of the saccadic parameters.

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

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

Disruptive behavior disorders and indicators of disinhibition in adolescents: The BRIEF-SR, anti-saccade task, and D-KEFS color-word interference test

Disinhibition contributes to the development of disruptive behavior disorders (DBD) in adolescents. Self-reports and behavioral tasks are commonly used to assess disinhibition, each with their unique strengths and limitations. Accordingly, it is important to identify which measure, or combination thereof, is the most effective in predicting DBD symptoms. This study assessed the relationship between DBD (symptoms of ADHD/ODD/CD) and two behavioral disinhibition tasks: the anti-saccade task and the D-KEFS color-word interference test, as well as a self-report measure (the BRIEF-SR). The results indicated that the BRIEF-Inhibit scale accounted for the majority of the variance in the DBD sum score. The anti-saccade task and color-word interference test were also significantly associated with an increase in the number of DBD symptoms endorsed. These behavioral tasks accounted for 9% additional variance than the self-report alone. Therefore, combining self-report measures with behavioral disinhibition tasks may provide the most thorough assessment of adolescent DBD.

A device for continuous monitoring of true central fixation based on foveal birefringence

A device for continuous monitoring of central fixation utilizes birefringence, the property of the Henle fibers surrounding the human fovea, to change the polarization state of light. A circular scan of retinal birefringence, where the scanning circle encompasses the fovea, allows identification of true central fixation-an assessment much needed in various applications in ophthalmology, psychology, and psychiatry. The device allows continuous monitoring for central fixation over an extended period of time in the presence of fixation targets and distracting stimuli, which may be helpful in detecting attention deficit hyperactivity disorder, autism spectrum disorders, and other disorders characterized by changes in the subject's ability to maintain fixation. A proof-of-concept has been obtained in a small study of ADHD patients and normal control subjects.

Die Wirksamkeit neuropsychologischer Trainingsverfahren bei Kindern und Jugendlichen mit Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS)

Aktuelle neuropsychologische Erkenntnisse zur Pathogenese von Aufmerksamkeitsdefizit-Hyperaktivitätsstörungen haben in jüngster Zeit verstärkt zur Untersuchung der Effektivität spezifischer Trainings- und Therapieverfahren der betroffenen kognitiven Defizite beigetragen. In der vorliegenden Übersicht wurden über eine Medline-Recherche die Ergebnisse bereits vorliegender neuropsychologischer Therapieverfahren zusammengetragen. Aufgrund der geringen Studienzahl auf diesem Gebiet wurden neben randomisierten Studien zum Teil Arbeiten mit geringerem Evidenzgrad einbezogen, zum Teil auch Einzelfallberichte. Als Suchwörter wurden verwendet: Kognitive Trainings und Behandlungsverfahren, neuropsychologische Behandlungsverfahren, computergestützte Behandlungsverfahren/-trainings bei ADHS. Die Ergebnisse der vorliegenden Studien lassen aufgrund der heterogenen Zusammensetzung der Studienkollektive, der Anwendung unterschiedlicher diagnostischer Kriterien, der Effektmessung, der Verwendung sehr unterschiedlicher Trainingsverfahren als auch der Behandlungsdauer nur sehr vorläufige Schlussfolgerungen auf deren Wirksamkeit zu. Auch der Grad der Generalisierung von Therapieeffekten verbleibt bislang unklar. Trotz der oben genannten Einschränkungen weisen die vorliegenden Studienergebnisse darauf hin, dass neuropsychologische Therapieverfahren zumindest in der Behandlung einiger spezifischer kognitiver Defizite wirksam sein könnten. Als nächster Schritt wären Replikationsstudien unter der Verwendung vergleichbarer Therapiemodule und -bedingungen bei homogenen Stichproben erforderlich.

Saccadic eye movement applications for psychiatric disorders

OBJECTIVE

The study presented here analyzed the patterns of relationship between oculomotor performance and psychopathology, focusing on depression, bipolar disorder, schizophrenia, attention-deficit hyperactivity disorder, and anxiety disorder.

METHODS

Scientific articles published from 1967 to 2013 in the PubMed/Medline, ISI Web of Knowledge, Cochrane, and SciELO databases were reviewed.

RESULTS

Saccadic eye movement appears to be heavily involved in psychiatric diseases covered in this review via a direct mechanism. The changes seen in the execution of eye movement tasks in patients with psychopathologies of various studies confirm that eye movement is associated with the cognitive and motor system.

CONCLUSION

Saccadic eye movement changes appear to be heavily involved in the psychiatric disorders covered in this review and may be considered a possible marker of some disorders. The few existing studies that approach the topic demonstrate a need to improve the experimental paradigms, as well as the methods of analysis. Most of them report behavioral variables (latency/reaction time), though electrophysiological measures are absent.

Medio-frontal and anterior temporal abnormalities in children with attention deficit hyperactivity disorder (ADHD) during an acoustic antisaccade task as revealed by electro-cortical source reconstruction

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders in children and adolescence. Impulsivity is one of three core symptoms and likely associated with inhibition difficulties. To date the neural correlate of the antisaccade task, a test of response inhibition, has not been studied in children with (or without) ADHD.

METHODS

Antisaccade responses to visual and acoustic cues were examined in nine unmedicated boys with ADHD (mean age 122.44 ± 20.81 months) and 14 healthy control children (mean age 115.64 ± 22.87 months, three girls) while an electroencephalogram (EEG) was recorded. Brain activity before saccade onset was reconstructed using a 23-source-montage.

RESULTS

When cues were acoustic, children with ADHD had a higher source activity than control children in Medio-Frontal Cortex (MFC) between -230 and -120 ms and in the left-hemispheric Temporal Anterior Cortex (TAC) between -112 and 0 ms before saccade onset, despite both groups performing similarly behaviourally (antisaccades errors and saccade latency). When visual cues were used EEG-activity preceding antisaccades did not differ between groups.

CONCLUSION

Children with ADHD exhibit altered functioning of the TAC and MFC during an antisaccade task elicited by acoustic cues. Children with ADHD need more source activation to reach the same behavioural level as control children.

Oculomotor and pupillometric indices of pro- and antisaccade performance in youth-onset psychosis and attention deficit/hyperactivity disorder

The goals of the study were to examine inhibitory deficits on the antisaccade task in 8- to 20-year olds with youth-onset psychosis or attention deficit/hyperactivity disorder (ADHD) and healthy controls and to examine if age-related changes in performance differed across groups. In addition to the conventional measures of performance, pupillary dilations were used to obtain estimates of phasic and tonic level of arousal. Results showed that the psychosis, but not the ADHD, group had elevated antisaccade error rates; however, variability of error rates was high in all groups. These inhibitory failures were accompanied by a lower level of momentary cognitive effort (as indexed by pupillary dilations). The largest differences between the control and clinical groups were found not in the expected indices of inhibition but in the probability of correcting inhibitory errors and in variability of antisaccade response times, which were correlated with each other. These findings did not appear to be attributable to a deficit in maintaining task instructions in mind in either disorder or lack of motivation in ADHD. Instead, results point to impairments in both clinical groups in sustaining attention on a trial-by-trial basis, resulting in deficits in self-monitoring. Thus, results show inhibitory deficits in the context of more general attentional impairments in both disorders.

Shared and nonshared symptoms in youth-onset psychosis and ADHD

OBJECTIVE

We compared ratings of behavior and attention problems between youth-onset psychosis and ADHD, two disorders in which attentional impairments play a key role, and examined the effect of psychostimulant use on age of onset in psychosis.

METHOD

Parent and teacher ratings of behavioral problems and ADHD symptoms were collected using the Achenbach CBCL, TRF, and SNAP-IV Teacher Rating Scales on 42 participants with psychosis, 36 with ADHD and 57 controls (ages 8-19).

RESULTS AND CONCLUSIONS

Results suggested that academic, externalizing, and attention problems reflect symptoms shared between the disorders, whereas internalizing, social and thought problems reflect factors that differ between disorders. Furthermore, participants with psychosis who had been prescribed psychostimulants had a younger age of onset of psychotic symptoms than those who had not. This difference could reflect dissimilarities in symptom severity symptom between subgroups or potentially harmful effects of psychostimulants in individuals predisposed to develop psychosis.

The influences of environmental enrichment, cognitive enhancement, and physical exercise on brain development: can we alter the developmental trajectory of ADHD?

Attention-deficit/Hyperactivity Disorder (ADHD) is characterized by a pervasive pattern of developmentally inappropriate inattentive, impulsive and hyperactive behaviors that typically begin during the preschool years and often persist into adulthood. The most effective and widely used treatments for ADHD are medication and behavior modification. These empirically-supported interventions are generally successful in reducing ADHD symptoms, but treatment effects are rarely maintained beyond the active intervention. Because ADHD is now generally thought of as a chronic disorder that is often present well into adolescence and early adulthood, the need for continued treatment throughout the lifetime is both costly and problematic for a number of logistical reasons. Therefore, it would be highly beneficial if treatments would have lasting effects that remain after the intervention is terminated. This review examines the burgeoning literature on the underlying neural determinants of ADHD along with research demonstrating powerful influences of environmental factors on brain development and functioning. Based upon these largely distinct scientific literatures, we propose an approach that employs directed play and physical exercise to promote brain growth which, in turn, could lead to the development of potentially more enduring treatments for the disorder.

Differential fractional anisotropy abnormalities in adolescents with ADHD or schizophrenia

Schizophrenia and Attention-Deficit/Hyperactivity Disorder (ADHD) are associated with similar deficits in working memory, attention, and inhibition. Both disorders also involve abnormalities of white matter integrity, possibly reflecting neural communication disruptions. There are likely some regional white matter abnormalities that underlie the common cognitive impairment, though also some regional abnormalities unique to each disorder. We used diffusion tensor imaging (DTI) to compare white matter integrity, as indicated by fractional anisotropy (FA), in adolescents with schizophrenia (n=15) or ADHD (n=14) and healthy controls (n=26). Schizophrenia patients had uniquely low FA, relative to the other two groups, in bilateral cerebral peduncles, anterior and posterior corpus callosum, right anterior corona radiata, and right superior longitudinal fasciculus. ADHD patients had uniquely high FA in left inferior and right superior frontal regions. Both clinical groups had lower FA than controls in left posterior fornix. The two disorders generally demonstrated distinct patterns of abnormal connectivity suggesting that common cognitive and behavioral deficits derive from distinct sources, though the posterior fornix may be involved in both disorders. Schizophrenia was associated with abnormally low FA in widespread circuitry indicative of general connectivity disruptions, whereas ADHD was associated with abnormally high FA in frontal networks that may indicate impaired branching of fibers.

Role of the hippocampus in goal-oriented tasks requiring retrieval of spatial versus non-spatial information

The role of the hippocampus in non-spatial memory has been issue of some controversy. To investigate the nature of dorsal hippocampus engagement in spatial and non-spatial memory we performed discrete excitotoxic lesions of this region before mice (C57/BL6) were trained in one of two tasks that required the animals to retrieve a hidden food reward. In the visuospatial task animals had to remember a particular spatial location, independent of odor cues. In contrast, in a non-spatial olfactory task animals had to remember a particular odor, independent of spatial location. The mice were trained in one of these tasks over a period of three days. We found that lesions restricted to the dorsal hippocampus affected performance only in the spatial task. In contrast, lesions that also encompassed a larger portion of the ventral hippocampus caused a moderate deficit in the olfactory task. These results are consistent with the role of the dorsal hippocampus in long-term spatial episodic memory, and support the involvement of larger portions of the hippocampus on the encoding of non-spatial olfactory representations.

Cognitive control and attentional selection in adolescents with ADHD versus ADD

An important research question is whether Attention Deficit Hyperactivity Disorder (ADHD) is related to early- or late-stage attentional control mechanisms and whether this differentiates a nonhyperactive subtype (ADD). This question was addressed in a sample of 145 ADD/ADHD and typically developing comparison adolescents (aged 13-17). Attentional blink and antisaccade tasks were used to assay early- and late-stage control, respectively. ADD was defined using normative cutoffs to ensure low activity level in children who otherwise met full criteria for ADHD. The ADD group had an attenuated attentional blink versus controls and ADHD-combined. The effect was not produced using DSM--IV definition of ADHD-primarily inattentive type or DSM symptom counts. ADHD-combined showed greater weakness in response inhibition, as manifest in the antisaccade task. Combining tasks yielded an interaction differentiating group performance on the two tasks.

Incidental and intentional sequence learning in youth-onset psychosis and Attention-Deficit/Hyperactivity Disorder (ADHD)

The goal was to compare incidental and intentional spatial sequence learning in youth-onset psychosis and ADHD. The authors tested 8- to 19-year-olds with psychosis or ADHD and healthy controls on a serial reaction time (RT) task and used manual and oculomotor measures to examine learning. Participants were also administered a block in which they were explicitly instructed to learn a sequence. As in our previous studies with healthy adults and children, oculomotor anticipations and RTs showed learning effects similar to those in the manual modality. Results showed intact sequence-specific learning but fewer oculomotor anticipations in both clinical groups during incidental learning. In intentional learning, only the psychosis group showed impairments compared to controls. There were no interactions between age and diagnosis. Thus, the psychosis group showed relatively preserved incidental learning despite impairments in intentional learning. Additionally, both clinical groups showed impairments in the ability to search for, extract, and anticipate regularities (whether the regularities were there or not), but not in the ability to respond to these regularities when they were there.

Regulation of cognitive resources during an n-back task in youth-onset psychosis and attention-deficit/hyperactivity disorder (ADHD)

The goals of the current study were to use behavioral and pupillary measures to examine working memory on a spatial n-back task in 8-20-year-olds with youth-onset psychosis or ADHD (Combined subtype) and healthy controls to determine the contribution of different attentional factors to spatial working memory impairments, and to examine if age-related changes in performance differed across groups. Although both clinical groups had lower perceptual sensitivity on both 0- and 1-back, there was no evidence of an impairment in spatial working memory or differential order effects on the 0-back. Instead, results suggest that both clinical groups had difficulty encoding the stimuli. They also appeared to have difficulty maintaining attention and/or readiness to respond, and, to a lesser extent, recruiting resources on a trial-to-trial basis. It is likely that these attentional problems prevented the clinical groups from encoding the stimuli effectively and contributed to their general performance deficits.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.

Review of cognitive, cognitive-behavioral, and neural-based interventions for Attention-Deficit/Hyperactivity Disorder (ADHD)

Primary evidence-based treatment approaches for ADHD involve pharmacological and behavioral treatments. However, there continue to be investigations of cognitive-behavioral, cognitive, and neural-based intervention approaches that are not considered evidence-based practice. These particular treatments are summarized, as they all involve training in cognitive skills or cognitive strategies. We identified 26 studies (six cognitive-behavioral, six cognitive, and 14 neural-based), and calculated effect sizes where appropriate. Overall, our analysis suggests that further research is needed to determine the efficacy of these approaches on both cognitive and behavioral outcome measures, but that some of these methods show promise for treating ADHD. We discuss some important conceptual and methodological issues that need to be taken into account for future research in order to evaluate the clinical efficacy of these approaches.

Disorders of saccades

Saccades are rapid eye movements that assist vision by pointing the fovea of the retina, which contains the highest density of photoreceptors, at features of interest in the visual environment. A great deal is now known about the properties and neurobiology of saccades in both health and disease states. They have consequently become a valuable diagnostic and research tool. In this review, we describe the common saccadic disorders and their causes. We also highlight recent insights into the pathophysiologic mechanisms underlying these disorders and discuss how these insights have helped increase our understanding of the saccadic system as a whole.