Dissociation in performance of children with ADHD and high-functioning autism on a task of sustained attention

Attention deficit hyperactivity disorder (ADHD) and autism are two neurodevelopmental disorders associated with prominent executive dysfunction, which may be underpinned by disruption within fronto-striatal and fronto-parietal circuits. We probed executive function in these disorders using a sustained attention task with a validated brain-behaviour basis. Twenty-three children with ADHD, 21 children with high-functioning autism (HFA) and 18 control children were tested on the Sustained Attention to Response Task (SART). In a fixed sequence version of the task, children were required to withhold their response to a predictably occurring no-go target (3) in a 1-9 digit sequence; in the random version the sequence was unpredictable. The ADHD group showed clear deficits in response inhibition and sustained attention, through higher errors of commission and omission on both SART versions. The HFA group showed no sustained attention deficits, through a normal number of omission errors on both SART versions. The HFA group showed dissociation in response inhibition performance, as indexed by commission errors. On the Fixed SART, a normal number of errors was made, however when the stimuli were randomised, the HFA group made as many commission errors as the ADHD group. Greater slow-frequency variability in response time and a slowing in mean response time by the ADHD group suggested impaired arousal processes. The ADHD group showed greater fast-frequency variability in response time, indicative of impaired top-down control, relative to the HFA and control groups. These data imply involvement of fronto-parietal attentional networks and sub-cortical arousal systems in the pathology of ADHD and prefrontal cortex dysfunction in children with HFA.     

Dissociation in response to methylphenidate on response variability in a group of medication naïve children with ADHD

Increased variability in reaction time (RT) has been proposed as a cardinal feature of attention deficit hyperactivity disorder (ADHD). Increased variability during sustained attention tasks may reflect inefficient fronto-striatal and fronto-parietal circuitry; activity within these circuits is modulated by the catecholamines. A disruption to dopamine signaling is suggested in ADHD that may be ameliorated by methylphenidate (MPH). This study investigated the effects of MPH administration on the variability in RT and error performance on a sustained attention task of a group of 31 medication naïve children with ADHD, compared with 22 non-ADHD, non-medicated, control children. All children performed the fixed-sequence sustained attention to response task (SART) at two time-points: at baseline and after six weeks. The children with ADHD were tested when medication naive at baseline and after six weeks of treatment with MPH and whilst on medication. The medication naïve children with ADHD performed the SART with greater errors of commission and omission when compared with the control group. They demonstrated greater standard deviation of RT and fast moment-to-moment variability. They did not differ significantly from the control group in terms of slow variability in RT. MPH administration resulted in reduced and normalised levels of commission errors and fast, moment-to-moment variability in RT. MPH did not affect the rate of omission errors, standard deviation of RT or slow frequency variability in RT. MPH administration may have a specific effect on those performance components that reflect sustained attention and top–down control rather than arousal.     

Performance patterns in Conners' CPT among children with attention deficit hyperactivity disorder and dyslexia

This study investigated the performance of children with attention deficit hyperactivity disorder (ADHD) and dyslexia using Conners' Continuous Performance Test (CCPT). The clinical groups were composed of 52 children with ADHD and 32 children with dyslexia. Performance in the CCPT was evaluated using ANCOVA to compare the clinical groups with the normative Brazilian sample. The ADHD group performed worse than the normative sample in almost all of the measurements, except for reaction time and response style. The dyslexia group scored higher on commissions, variability, perseverations and inconsistency in the reaction time over the six time blocks (Hit SE Block Change) than the children in the normative Brazilian sample. The ADHD and dyslexia groups differed in omission measurements, Hit RT SE, variability, perseverations, Hit RT Interstimulus Intervals (ISI) Change and Hit SE ISI Change. We thus found that the dyslexia group had specific deficit patterns, with greater response to non-target stimuli, greater perseveration and response variability, and difficulties in hit reaction time as the test progressed.     

Reduced electrodermal response to errors predicts poor sustained attention performance in attention deficit hyperactivity disorder

Research into attention deficit hyperactivity disorder (ADHD) has indicated abnormalities in electrodermal system activity (EDA) and separately, deficits in sustained attention. Here we asked whether reduced EDA in ADHD was consequential for the attention problems associated with this disorder. On a sustained attention task ADHD participants had higher overall error rates and exhibited a marked decrease in skin conductance responses (SCRs) to errors, relative to control children. Further, sustained attention errors were predicted by SCR amplitudes. Evidence of post-error slowing in both groups suggested comparable error awareness. It is proposed that attenuation of the normal autonomic response to errors reflects impairment in ADHD participants' psychological response to error significance and results in decreased behavioural correction and hence poorer sustained attention.     

Variability in time reproduction: difference in ADHD combined and inattentive subtypes

OBJECTIVE: To examine the relationship between time reproduction, performance variability, and sustained attention deficits in children with attention-deficit/hyperactivity disorder (ADHD) combined (ADHD-C) and inattentive (ADHD-I) subtypes, relative to matched controls. METHOD: Participants (age range 7.1-14.1 years) performed a time reproduction task. A subset of the ADHD group was also tested on the Sustained Attention to Response Test. Absolute discrepancy, accuracy coefficient, and intraindividual variability scores on the time reproduction task were compared across the three groups (ADHD-C: N = 20; ADHD-I: N = 19; controls: N = 44) and correlated with the Sustained Attention to Response Test. RESULTS: First, significantly better performance was observed in matched controls than in children with ADHD on the time reproduction task. Second, there was a significant difference between the two ADHD subtypes in the variability of the size of errors made at high time intervals (36-60 seconds). Third, intraindividual performance variability in the direction (over- versus underestimations) of time reproductions correlated with sustained attention performance. CONCLUSIONS: Children with ADHD varied more in the size and direction of their time reproduction errors than control children. Those with ADHD-C demonstrated more intraindividual variability than did those with ADHD-I in the size of their errors. The data provide support for a relationship between sustained attention and time reproduction. This relationship has previously been inferred from common right-lateralized neural circuitry that is thought to subserve these processes.     

Dissecting the attention deficit hyperactivity disorder (ADHD) phenotype: sustained attention, response variability and spatial attentional asymmetries in relation to dopamine transporter (DAT1) genotype

ADHD is a childhood-onset behavioural disorder with a heterogeneous profile of neuropsychological impairment. Neuropsychological heterogeneity may, in part, reflect underlying genetic differences. Here we examined sustained attention, response variability and spatial attentional asymmetries in a sample of children and adolescents with ADHD (n=22) in relation to dopamine transporter genotype (DAT1) and also controls (n=20). Participants performed the sustained attention to response task (SART) (testing sustained attention and response variability) and the greyscales task (a perceptual measure of attentional bias). The latter has previously been shown to yield a robust leftward attentional asymmetry in healthy subjects. The 10-repeat allele of the DAT1 gene has been associated with ADHD in a number of studies and appears to have biological significance. The ADHD group was sub-divided into those individuals with two copies of the "high-risk" 10-repeat allele (high-risk DAT1) versus those with one or no copies of this allele (low-risk DAT1). The high-risk DAT1 ADHD group displayed greater response variability on the SART than either the low-risk DAT1 group or healthy controls, whereas the latter two groups did not differ. Further, the high-risk DAT1 group showed an attenuated spatial asymmetry, relative to the low-risk DAT1 ADHD group, who showed the typical leftward attentional asymmetry. Our results suggest that the 10-repeat DAT1 allele may mediate neuropsychological impairment in ADHD. The application of molecular genetics may help to define neuropsychological impaired subgroups of ADHD.     

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.     

注意缺陷多动障碍儿童错误监测对照研究

目的探讨注意缺陷多动障碍(ADHD)儿童的错误监测功能。方法选取2012年1月-2013年12月在安徽省精神卫生防治中心心理门诊就诊的,符合《中国精神障碍分类与诊断标准(第3版)》(CCMD-3)ADHD诊断标准的儿童30例以及与其人口学资料相匹配的30名健康儿童。两组均进行错误监测任务试验,观察记录全对数(AC),全错数(AE),错评数(EA),脱失数以及选择反应时、评估反应时。结果 ADHD儿童在错误监测任务中全对(AC)、全错(AE)、脱失数目、选择反应时以及评估反应时均差于健康儿童[(120.13±16.78)次vs.(134.93±13.87)次,(11.73±9.07)次vs.(6.10±6.09)次,(10.70±7.57)次vs.(4.73±4.98)次,(697.15±175.56)ms vs.(539.48±128.92)ms,(488.64±174.77)ms vs.(390.58±196.36)ms],差异均有统计学意义(t=-3.965~3.723,P0.05)。结论 ADHD儿童存在错误监测方面的损伤。     

Attention and executive functions profile in drug naive ADHD subtypes

Attention deficit hyperactivity disorder (ADHD) has been associated with executive functioning and sustained and divided attention deficits. In order to clarify the questions on neurocognitive impairment in ADHD, we investigated the presence of specific executive functions (EFs) and attention deficit patterns in ADHD clinical subtypes. 50 patients with ADHD and 44 controls were evaluated. All subjects were boys and performed a clinical-psychopathological and neuropsychological battery. Five main domains of EFs and attention were studied. Executive functions-related neurocognitive abilities were used as control tasks. ADHD patients, inattentive and combined subtypes differ from controls on response inhibition, divided attention, phonological, and visual object working memory and on variability of reaction times measured with CPT. Comparison of ADHD subtypes, in five main domains of EFs, did not show evidence of different executive functioning profiles. Response inhibition can predict performance on working memory tests but it cannot predict performance on divided attention/set shifting and on sustained attention. ADHD boys exhibit a selective impairment on executive functions and attention tasks. These data suggest the involvement of partially independent neural circuits which control inhibition and divided attention in ADHD. Since right prefrontal cortex seems to be crucial in controlling response inhibition, while left dorsolateral prefrontal cortex seems important in modulating divided attention, these areas are deputated to be involved in the pathogenesis of neuropsychological deficits in ADHD subtypes. In addition, this study candidates the impairment in phonological and visual-object working memory as a possible neuropsychological trait in ADHD males with inattentive or combined subtypes.     

Cognitive remediation in ADHD: effects of periodic non-contingent alerts on sustained attention to response

Few studies have attempted direct cognitive remediation of attention deficits in attention-deficit hyperactivity disorder (ADHD). The present study investigated the efficacy of periodic non-informative alerting cues for improving sustaining attention in ADHD. This technique is known to improve sustained attention in right frontal injury patients and may be effective in ADHD, given that this disorder has also been linked with right frontal dysfunction. Fifteen children with ADHD and 15 matched controls completed four blocks of a modified version of the Sustained Attention to Response Task (SART). Eight random non-contingent alerts were introduced on two of these blocks as a cue for participants to adopt a more supervisory stance to their performance. While the alerting cues did not alter the total number of commission errors committed by ADHD children over a task block, they did produce a significant short-term reduction in commission errors in the period immediately following an alerting cue. Our data demonstrate that sustained attention performance can be enhanced in children with ADHD using a simple cognitive training strategy. Methods from the field of cognitive rehabilitation may be viably applied to the remediation of attention deficits in ADHD.     

Visual sustained attention in a child psychiatric population

OBJECTIVE: To increase knowledge of the diversity and specificity of sustained attention deficits in children with attention-deficit hyperactivity disorder (ADHD), with special reference to the issue of distinguishing between children with ADHD and children with other psychiatric diagnoses. METHOD: A visual sustained attention task was used to compare 52 boys with ADHD with 55 normal controls, 29 boys with oppositional defiant disorder or conduct disorder (ODD/CD), 29 boys with anxiety or dysthymia (ANX/DYS), 43 boys with pervasive developmental disorder, 24 boys with ADHD plus ODD/CD, and 14 boys with ADHD plus ANX/DYS. RESULTS: Compared with normal controls, children with ADHD were slower, were more inaccurate, were more impulsive, were less responsive to feedback, and showed less perceptual sensitivity and stability of performance, resulting in a marked decrease in vigilance over time. Unresponsiveness to feedback and the extent of the decrease in vigilance during time on task were found to be the only factors that distinguished children with ADHD from children with other diagnoses. CONCLUSION: Although only children with ADHD are characterized primarily by "attention deficit," sustained attention deficit is common to a certain extent to all children with psychiatric disorders.     

Cognitive remediation in ADHD: Effects of periodic non-contingent alerts on sustained attention to response

Few studies have attempted direct cognitive remediation of attention deficits in attention-deficit hyperactivity disorder (ADHD). The present study investigated the efficacy of periodic non-informative alerting cues for improving sustaining attention in ADHD. This technique is known to improve sustained attention in right frontal injury patients and may be effective in ADHD, given that this disorder has also been linked with right frontal dysfunction. Fifteen children with ADHD and 15 matched controls completed four blocks of a modified version of the Sustained Attention to Response Task (SART). Eight random non-contingent alerts were introduced on two of these blocks as a cue for participants to adopt a more supervisory stance to their performance. While the alerting cues did not alter the total number of commission errors committed by ADHD children over a task block, they did produce a significant short-term reduction in commission errors in the period immediately following an alerting cue. Our data demonstrate that sustained attention performance can be enhanced in children with ADHD using a simple cognitive training strategy. Methods from the field of cognitive rehabilitation may be viably applied to the remediation of attention deficits in ADHD.     

Differentiating attention deficits in children with fetal alcohol spectrum disorder or attention‐deficit–hyperactivity disorder

Aim The attention and inhibition problems found in children with attention‐deficit–hyperactivity disorder (ADHD) are also common in children with fetal alcohol spectrum disorders (FASDs). Attempts to distinguish ADHD from FASDs in terms of these deficits are rare and were pursued in this study. Method A total of 116 children (47 with ADHD, 31 males, 16 females; 30 with FASDs, 17 males, 13 females; and 39 comparison children, 20 males, 19 females) participated. The mean age was 9 years 4 months (SD 1y 8mo) in the ADHD groups, 8 years 10 months (SD 1y 2mo) in the FASD group, and 9 years 1 month (SD 1y 1mo) in the comparison group. Sustained attention was tested with a slow event rate continuous performance task (CPT). Inhibitory control was tested with both a slow and fast event rate Go/No‐Go task. Results On the CPT task, children with ADHD, combined type (ADHD‐C), ADHD, primarily inattentive type (ADHD‐PI), and FASDs showed greater declines in task performance as a function of time than comparison children, suggesting sustained attention problems in all clinical groups. Children’s Go/No‐Go performance was event‐rate dependent, with the ADHD‐C group being affected in the slow condition and the ADHD‐PI and FASD groups having problems with the fast condition. Interpretation Children with ADHD‐C are typically impaired in handling understimulation, while children with FASDs may have problems with overstimulation. The dissociation in responsivity to event rate between groups may have significant differential diagnostic value.     

Sustained attention in sensory modulation disorder and attention deficit/hyperactivity disorder

BackgroundThere are high comorbidity rates between sensory modulation disorder (SMD) and attention deficit hyperactivity disorder (ADHD). Knowledge regarding the objective neuropsychological differentiation between them is scarce.AimThis study examines the effects of SMD and ADHD on a sustained attention task with and without aversive auditory conditions.MethodSixty six young adult females were tested on the Conjunctive - Continuous Performance Task-Visual (CCPT-V) measuring sustained attention, under two conditions: 1) aversive condition (with the three most aversive sounds chosen by the participant), and 2) non-aversive condition (without sounds).ResultsBoth the SMD and ADHD factors exhibited performance deficits in the sustained attention task. All study participants performed worse on both sustained attention and speed of processing when aversive sounds were present.ConclusionWe conclude that impaired sustained attention cannot differentiate between SMD and ADHD. Hence, these results should be taken under consideration in the assessment process of ADHD vs. SMD.     

The cognitive genetics of attention deficit hyperactivity disorder (ADHD): sustained attention as a candidate phenotype

Here we describe the application of cognitive genetics to the study of attention deficit hyperactivity disorder (ADHD). Cognitive genetics owes much to the pioneering work of cognitive neuropsychologists such as John Marshall, whose careful observations of cognitive dissociations between brain-lesioned patients greatly advanced the theoretical understanding of normal cognitive function. These theories have in turn helped to constrain linkages between candidate genes and cognitive processes and thus help to drive the relatively new field of cognitive genetics in a hypothesis-driven fashion. We examined the relationship between sustained attention deficits in ADHD and genetic variation in a catecholamine-related gene, dopamine beta hydroxylase (DbetaH). DBH encodes the enzyme that converts dopamine to noradrenaline and is crucial to catecholamine regulation. A polymorphism with the DBH gene has been associated with ADHD. In fifty-two children with ADHD, we examined whether variation in the Taq I DBH gene polymorphism was related to sustained attention performance. Participants performed the Sustained Attention to Response Test (SART). Performance on the SART discriminates ADHD from control children, and in imaging work, is associated with right frontoparietal activation. A significant effect of DBH genotype was found on SART performance measures. Children possessing two copies of the ADHD-associated risk allele (A2) had significantly poorer sustained attention than those ADHD children who did not possess this allele or a non-genotyped control group. The DBH gene may contribute to the susceptibility for ADHD, in part because of its varying effects on the development of brain mechanisms mediating sustained attention.     

Closed-Loop Neurofeedback of α Synchrony during Goal-Directed Attention

α Oscillations in sensory cortex, under frontal control, desynchronize during attentive preparation. Here, in a selective attention study with simultaneous EEG in humans of either sex, we first demonstrate that diminished anticipatory α synchrony between the mid-frontal region of the dorsal attention network and ventral visual sensory cortex [frontal-sensory synchrony (FSS)] significantly correlates with greater task performance. Then, in a double-blind, randomized controlled study in healthy adults, we implement closed-loop neurofeedback (NF) of the anticipatory α FSS signal over 10 d of training. We refer to this closed-loop experimental approach of rapid NF integrated within a cognitive task as cognitive NF (cNF). We show that cNF results in significant trial-by-trial modulation of the anticipatory α FSS measure during training, concomitant plasticity of stimulus-evoked α/θ responses, as well as transfer of benefits to response time (RT) improvements on a standard test of sustained attention. In a third study, we implement cNF training in children with attention deficit hyperactivity disorder (ADHD), replicating trial-by-trial modulation of the anticipatory α FSS signal as well as significant improvement of sustained attention RTs. These first findings demonstrate the basic mechanisms and translational utility of rapid cognitive-task-integrated NF.SIGNIFICANCE STATEMENT When humans prepare to attend to incoming sensory information, neural oscillations in the α band (8–14 Hz) undergo desynchronization under the control of prefrontal cortex. Here, in an attention study with electroencephalography, we first show that frontal-sensory synchrony (FSS) of α oscillations during attentive preparation significantly correlates with task performance. Then, in a randomized controlled study in healthy adults, we show that neurofeedback (NF) training of this α FSS signal within the attention task is feasible. We show that this rapid cognitive NF (cNF) approach engenders plasticity of stimulus-evoked neural responses, and improves performance on a standard test of sustained attention. In a final study, we implement cNF in children with attention deficit hyperactivity disorder (ADHD), replicating the improvement of sustained attention found in adults.     

Increased intra-individual reaction time variability in attention-deficit/hyperactivity disorder across response inhibition tasks with different cognitive demands

One of the most consistent findings in children with ADHD is increased moment-to-moment variability in reaction time (RT). The source of increased RT variability can be examined using ex-Gaussian analyses that divide variability into normal and exponential components and Fast Fourier transform (FFT) that allow for detailed examination of the frequency of responses in the exponential distribution. Prior studies of ADHD using these methods have produced variable results, potentially related to differences in task demand. The present study sought to examine the profile of RT variability in ADHD using two Go/No-go tasks with differing levels of cognitive demand. A total of 140 children (57 with ADHD and 83 typically developing controls), ages 8–13 years, completed both a “simple” Go/No-go task and a more “complex” Go/No-go task with increased working memory load. Repeated measures ANOVA of ex-Gaussian functions revealed for both tasks children with ADHD demonstrated increased variability in both the normal/Gaussian (significantly elevated sigma) and the exponential (significantly elevated tau) components. In contrast, FFT analysis of the exponential component revealed a significant task × diagnosis interaction, such that infrequent slow responses in ADHD differed depending on task demand (i.e., for the simple task, increased power in the 0.027–0.074 Hz frequency band; for the complex task, decreased power in the 0.074–0.202 Hz band). The ex-Gaussian findings revealing increased variability in both the normal (sigma) and exponential (tau) components for the ADHD group, suggest that both impaired response preparation and infrequent “lapses in attention” contribute to increased variability in ADHD. FFT analyses reveal that the periodicity of intermittent lapses of attention in ADHD varies with task demand. The findings provide further support for intra-individual variability as a candidate intermediate endophenotype of ADHD.     

Within-subject variability during spatial working memory in children with ADHD: an event-related potentials study

Working memory (WM) dysfunction and increased within-subject variability are known issues in attention deficit/hyperactivity disorder (ADHD) patients. Little is known about the electrophysiological characteristics of this variability. We evaluated behavioral and electrophysiological within-subject variability taking developmental aspects into account in a group of ADHD patients. Multichannel (n = 31) event-related potentials (ERP) were measured during a visuo-spatial backmatching task; 44 children (8–16 years old) were tested: 22 children with ADHD, combined (n = 17) and inattentive (n = 5) type, and 22 age- and intelligence-matched control children. One-backmatching (BM1) and two-backmatching (BM2) tasks were performed. Classical behavioral parameters and target and nontarget ERP were compared between groups. In addition, motor response variability and ERP amplitude variability were studied. Age-related changes in both motor response and ERP amplitude variability were analyzed in each group. Attention deficit/hyperactivity disorder children made more commission errors, which was more pronounced in the difficult (BM2) task. No difference between groups was found in ERP amplitude and in motor response variability. However, ADHD patients had higher ERP amplitude variability, which was again more pronounced in the difficult WM task. A delayed maturation of amplitude variability was seen in ADHD patients with a slower than in controls decrease in variability with age. This amplitude variability was correlated with the number of commissions, but in an opposite way for ADHD and control children. Our findings indicate an impaired visuo-spatial WM processing in ADHD children with greater ERP amplitude variability compared to controls. Our results also support the view of a delayed cortical development of visuo-spatial WM circuits in this disorder.     

Preliminary fMRI findings on the effects of event rate in adults with ADHD

Inhibition problems in attention deficit hyperactivity disorder (ADHD) are sensitive to stimulus event rate. This pilot study explores the neural basis of this increased susceptibility to event rate in ADHD. Event-related functional magnetic resonance imaging was used in conjunction with the administration of a fast (1.5 s) and a slow (7 s) Go/No-Go task. Brain activity patterns and reaction times of ten young male adults with ADHD (two of whom were in partial remission) and ten healthy male controls were compared. The ADHD group responded slower than controls with greater variability but with similar number of errors. Accurate response inhibition in the ADHD group in the slow condition was associated with widespread fronto-striatal activation, including the thalamus. For correct Go trials only, the ADHD group compared with controls showed substantial under-activation in the slow condition. The observed abnormal brain activation in the slow condition in adults with ADHD supports a fronto-striatal etiology, and underlines a presumed activation regulation deficit. Larger sample sizes to further validate these preliminary findings are needed.     

Gait in attention deficit hyperactivity disorder

Abstract Background Cognitive function and the loading of attention presumably play an important role in gait as well as in fall risk, but previous work has not demonstrated this in any cause-and-effect way. Objectives To gain insight into the relationship between gait and cognitive function, we sought: (1) To compare the gait rhythmicity (stride time variability) of children with attention deficit hyperactivity disorder (ADHD) to controls, (2) To test the hypothesis that dual tasking leads to increased stride-to-stride variability in ADHD, and (3) To test whether pharmacological treatment that relieves ADHD symptoms reduces stride-to-stride variability. Patients and Methods Gait was quantified in children with ADHD and in age-matched healthy controls under single task and dual task conditions on three occasions: off medications (both groups) and, in the ADHD group, after double blinded, randomized administration of methylphenidate (MPH) or placebo. Results At baseline, children with ADHD tended to walk with increased stride-to-stride variability compared to the controls during the single task condition (p = 0.09). During dual task walking, stride time variability was significantly reduced in the children with ADHD (p < 0.004), but not in the controls. In the children with ADHD, the placebo did not significantly affect stride-to-stride variability or the dual tasking response. In contrast, stride time variability was significantly reduced on MPH (p < 0.001) such that dual tasking no longer affected variability. Conclusions The present findings demonstrate alterations in the gait of children with ADHD, support a cause and effect link between cognitive function and gait, and suggest that enhancement of attention abilities may, in certain populations, improve gait rhythmicity.