Attention-deficit/hyperactivity Disorder Participants Research Articles

Temporal reproduction and its neuroanatomical correlates in adults with attention deficit hyperactivity disorder and their unaffected first-degree relatives.

Little is known about time perception, its putative role as cognitive endophenotype, and its neuroanatomical underpinnings in adults with attention deficit hyperactivity disorder (ADHD). Twenty adults with ADHD, 20 unaffected first-degree relatives and 20 typically developing controls matched for age and gender undertook structural magnetic resonance imaging scans. Voxel-based morphometry with DARTEL was performed to obtain regional grey-matter volumes. Temporal processing was investigated as a putative cognitive endophenotype using a temporal reproduction paradigm. General linear modelling was employed to examine the relationship between temporal reproduction performances and grey-matter volumes. ADHD participants were impaired in temporal reproduction and unaffected first-degree relatives performed in between their ADHD probands and typically developing controls. Increased grey-matter volume in the cerebellum was associated with poorer temporal reproduction performance. Adults with ADHD are impaired in time reproduction. Performances of the unaffected first-degree relatives are in between ADHD relatives and controls, suggesting that time reproduction might be a cognitive endophenotype for adult ADHD. The cerebellum is involved in time reproduction and might play a role in driving time performances.

Double-dissociation between the mechanism leading to impulsivity and inattention in Attention Deficit Hyperactivity Disorder: A resting-state functional connectivity study

Two core symptoms characterize Attention Deficit Hyperactivity Disorder (ADHD) subtypes: inattentiveness and hyperactivity–impulsivity. While previous brain imaging research investigated ADHD as if it was a homogenous condition, its two core symptoms may originate from different brain mechanisms. We, therefore, hypothesized that the functional connectivity of cortico-striatal and attentional networks would be different between ADHD subtypes. We studied 165 children (mean age 10.93 years; age range, 7–17 year old) diagnosed as having ADHD based on their revised Conner's rating scale score and 170 typical developing individuals (mean age 11.46 years; age range, 7–17 year old) using resting state functional fMRI. Groups were matched for age, IQ and head motion during the MRI acquisition. We fractionated the ADHD group into predominantly inattentive, hyperactive–impulsive and combined subtypes based on their revised Conner's rating scale score. We then analyzed differences in resting state functional connectivity of the cortico-striatal and attentional networks between these subtypes. We found a double dissociation of functional connectivity in the cortico-striatal and ventral attentional networks, reflecting the subtypes of the ADHD participants. Particularly, the hyperactive–impulsive subtype was associated with increased connectivity in cortico-striatal network, whereas the inattentive subtype was associated with increased connectivity in the right ventral attention network. Our study demonstrated for the first time a right lateralized, double dissociation between specific networks associated with hyperactivity–impulsivity and inattentiveness in ADHD children, providing a biological basis for exploring symptom dimensions and revealing potential targets for more personalized treatments.

Virtual-reality-based attention assessment of ADHD: ClinicaVR: Classroom-CPT versus a traditional continuous performance test

ABSTRACTVirtual-reality-based assessment may be a good alternative to classical or computerized neuropsychological assessment due to increased ecological validity. ClinicaVR: Classroom-CPT (VC) is a neuropsychological test embedded in virtual reality that is designed to assess attention deficits in children with attention deficit hyperactivity disorder (ADHD) or other conditions associated with impaired attention. The present study aimed to (1) investigate the diagnostic validity of VC in comparison to a traditional continuous performance test (CPT), (2) explore the task difficulty of VC, (3) address the effect of distractors on the performance of ADHD participants and typically-developing (TD) controls, and (4) compare the two measures on cognitive absorption. A total of 33 children diagnosed with ADHD and 42 TD children, aged between 7 and 13 years, participated in the study and were tested with a traditional CPT or with VC, along with several cognitive measures and an adapted version of the Cognitive Absorption Scale. A mixed multivariate analysis of covariance (MANCOVA) revealed that the children with ADHD performed worse on correct responses had more commissions and omissions errors than the TD children, as well as slower target reaction times . The results showed significant differences between performance in the virtual environment and the traditional computerized one, with longer reaction times in virtual reality. The data analysis highlighted the negative influence of auditory distractors on attention performance in the case of the children with ADHD, but not for the TD children. Finally, the two measures did not differ on the cognitive absorption perceived by the children.

Increased ongoing neural variability in ADHD

Attention Deficit Hyperactivity Disorder (ADHD) has been described as a disorder where frequent lapses of attention impair the ability of an individual to focus/attend in a sustained manner, thereby generating abnormally large intra-individual behavioral variability across trials. Indeed, increased reaction time (RT) variability is a fundamental behavioral characteristic of individuals with ADHD found across a large number of cognitive tasks. But what is the underlying neurophysiology that might generate such behavioral instability? Here, we examined trial-by-trial EEG response variability to visual and auditory stimuli while subjects' attention was diverted to an unrelated task at the fixation cross. Comparisons between adult ADHD and control participants revealed that neural response variability was significantly larger in the ADHD group as compared with the control group in both sensory modalities. Importantly, larger trial-by-trial variability in ADHD was apparent before and after stimulus presentation as well as in trials where the stimulus was omitted, suggesting that ongoing (rather than stimulus-evoked) neural activity is continuously more variable (noisier) in ADHD. While the patho-physiological mechanisms causing this increased neural variability remain unknown, they appear to act continuously rather than being tied to a specific sensory or cognitive process.

The influence of shift work on systolic and diastolic pressure, pulse pressure, and dipping patterns on healthy medicine residents

Conduct disorder (CD) is associated with impairments in facial emotion recognition. However, CD commonly co-occurs with attention-deficit/hyperactivity disorder (ADHD); thus, it is unclear whether these impairments are explained by ADHD or by one of its core features—inattention. We explored whether emotion recognition impairments are specific to individuals with ADHD and comorbid CD while also examining the mechanisms that might explain such deficits.A total of 63 male and female adolescents with ADHD (mean age = 14.2 years, age range = 11–18 years) and with (ADHD+CD) or without (ADHD) comorbid CD, and 41 typically developing controls (healthy controls [HC]; mean age = 15.5, age range = 11–18 years) performed an emotion recognition task with concurrent eye-tracking.Participants with ADHD+CD were less accurate at recognizing fear and neutral faces, and more likely to confuse fear with anger than participants with ADHD alone and HC. Both ADHD subgroups fixated the eye region less than HC. Although there was a negative correlation between ADHD symptom severity and eye fixation duration, only CD severity was inversely related to emotion recognition accuracy.Only ADHD participants with comorbid CD showed impairments in emotion recognition, suggesting that these deficits are specific to individuals with conduct problems. However, lack of attention to the eye region of faces appears to be a characteristic of ADHD. These findings suggest that emotion recognition impairments in those with ADHD+CD are related to misinterpretation rather than poor attention, offering interesting opportunities for intervention.

Dissociation of working memory impairments and attention-deficit/hyperactivity disorder in the brain.

Prevailing neuropsychological models of attention-deficit/hyperactivity disorder (ADHD) propose that ADHD arises from deficits in executive functions such as working memory, but accumulating clinical evidence suggests a dissociation between ADHD and executive dysfunctions. This study examined whether ADHD and working memory capacity are behaviorally and neurobiologically separable using functional magnetic resonance imaging (fMRI). Participants diagnosed with ADHD in childhood who subsequently remitted or persisted in their diagnosis as adults were characterized at follow-up in adulthood as either impaired or unimpaired in spatial working memory relative to controls who never had ADHD. ADHD participants with impaired spatial working memory performed worse than controls and ADHD participants with unimpaired working memory during an n-back working memory task while being scanned. Both controls and ADHD participants with unimpaired working memory exhibited significant linearly increasing activation in the inferior frontal junction, precuneus, lingual gyrus, and cerebellum as a function of working-memory load, and these activations did not differ significantly between these groups. ADHD participants with impaired working memory exhibited significant hypoactivation in the same regions, which was significantly different than both control participants and ADHD participants with unimpaired working memory. These findings support both a behavioral and neurobiological dissociation between ADHD and working memory capacity.

Lack of global precedence and global-to-local interference without local processing deficit: A robust finding in children with attention-deficit/hyperactivity disorder under different visual angles of the Navon task.

The Navon effect (Navon, 1977) is an automatic tendency to process the global picture prior to local details when processing compound patterns. However, several recent studies have reported that this effect is lacking in attention-deficit/hyperactivity disorder (ADHD). Although previous research has shown that the Navon effect is strongly affected by visual angles, whether this phenomenon will also be observed in ADHD is yet to be understood. We examine the lack of the Navon effect in ADHD under various visual angles to ensure that this phenomenon is not an artifact of saliency. By employing three different visual angles for the local stimuli, global and local processing of Navon-type hierarchical letters was examined in participants with ADHD (n = 15) and a comparison group (n = 17). ADHD participants presented with a lack of the Navon effect without local processing deficit regardless of visual angle, in comparison to non-ADHD participants. A lack of global precedence and global-to-local interference without local processing deficit can be generalized in ADHD. This suggests that people with ADHD experience difficulties in processing the "whole picture," and it also challenges the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; American Psychiatric Association, 2013) criteria of ADHD in which the failure to pay close attention to details was emphasized. Moreover, the current results have important implications for understanding ADHD and could also have significant clinical value.

Substance use in young adults with ADHD: Comorbidity and symptoms of inattention and hyperactivity/impulsivity

Young adults with attention deficit hyperactivity disorder (ADHD) are at high risk of substance use (SU). The aims of the current study were: 1) to examine the use of alcohol, tobacco, marijuana and other illegal drugs by adults with and without ADHD; 2) to compare the oppositional, conduct, anxiety, depression, sleep and antisocial personality symptoms of ADHD adults with SU and ADHD adults without SU; 3) to examine the ability of ADHD symptoms and conduct problems to predict SU. A total of 93 young adults, 43 without ADHD and 50 with a childhood diagnosis of ADHD, who were part of the Spanish sample of the Multicenter ADHD Genetics (IMAGE) study, collaborated in a follow-up evaluation 10.1 years later. ADHD participants were divided into two groups based on the presence or absence of SU. Statistically significant differences were found between young adults with and without ADHD in their use of tobacco, marijuana and alcohol. A statistically significant association was also shown between externalization problems and a greater risk of SU. Conduct problems, to a greater degree than ADHD symptoms, affect SU in ADHD adults.

ADHD and cannabis use in young adults examined using fMRI of a Go/NoGo task.

Children diagnosed with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for substance abuse. Response inhibition is a hallmark of ADHD, yet the combined effects of ADHD and regular substance use on neural networks associated with response inhibition are unknown. Task-based functional Magnetic Resonance Imaging (fMRI) data from young adults with childhood ADHD with (n = 25) and without (n = 25) cannabis use ≥ monthly in the past year were compared with a local normative comparison group (LNCG) with (n = 11) and without (n = 12) cannabis use. Go/NoGo behavioral and fMRI data were evaluated for main and interaction effects of ADHD diagnosis and cannabis use. ADHD participants made significantly more commission errors on NoGo trials than controls. ADHD participants also had less frontoparietal and frontostriatal activity, independent of cannabis use. No main effects of cannabis use on response inhibition or functional brain activation were observed. An interaction of ADHD diagnosis and cannabis use was found in the right hippocampus and cerebellar vermis, with increased recruitment of these regions in cannabis-using controls during correct response inhibition. ADHD participants had impaired response inhibition combined with less fronto-parietal/striatal activity, regardless of cannabis use history. Cannabis use did not impact behavioral response inhibition. Cannabis use was associated with hippocampal and cerebellar activation, areas rich in cannabinoid receptors, in LNCG but not ADHD participants. This may reflect recruitment of compensatory circuitry in cannabis using controls but not ADHD participants. Future studies targeting hippocampal and cerebellar-dependent function in these groups may provide further insight into how this circuitry is altered by ADHD and cannabis use.

Distinct effects of ASD and ADHD symptoms on reward anticipation in participants with ADHD, their unaffected siblings and healthy controls: a cross-sectional study

BackgroundAutism spectrum disorder (ASD) traits are continuously distributed throughout the population, and ASD symptoms are also frequently observed in patients with attention-deficit/hyperactivity disorder (ADHD). Both ASD and ADHD have been linked to alterations in reward-related neural processing. However, whether both symptom domains interact and/or have distinct effects on reward processing in healthy and ADHD populations is currently unknown.MethodsWe examined how variance in ASD and ADHD symptoms in individuals with ADHD and healthy participants was related to the behavioural and neural response to reward during a monetary incentive delay (MID) task. Participants (mean age: 17.7 years, range: 10–28 years) from the NeuroIMAGE study with a confirmed diagnosis of ADHD (n = 136), their unaffected siblings (n = 83), as well as healthy controls (n = 105) performed an MID task in a magnetic resonance imaging (MRI) scanner. ASD and ADHD symptom scores were used as predictors of the neural response to reward anticipation and reward receipt. Behavioural responses were modeled using linear mixed models; neural responses were analysed using FMRIB’s Software Library (FSL) proprietary mixed effects analysis (FLAMEO).ResultsASD and ADHD symptoms were associated with alterations in BOLD activity during reward anticipation, but not reward receipt. Specifically, ASD scores were related to increased insular activity during reward anticipation across the sample. No interaction was found between this effect and the presence of ADHD, suggesting that ASD symptoms had no differential effect in ADHD and healthy populations. ADHD symptom scores were associated with reduced dorsolateral prefrontal activity during reward anticipation. No interactions were found between the effects of ASD and ADHD symptoms on reward processing.ConclusionsVariance in ASD and ADHD symptoms separately influence neural processing during reward anticipation in both individuals with (an increased risk of) ADHD and healthy participants. Our findings therefore suggest that both symptom domains affect reward processing through distinct mechanisms, underscoring the importance of multidimensional and multimodal assessment in psychiatry.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-015-0043-y) contains supplementary material, which is available to authorized users.

A 4-year follow-up of attention-deficit/hyperactivity disorder in a population sample.

Prior follow-up studies of attention-deficit/hyperactivity disorder (ADHD) ascertained ADHD cases in clinical samples mostly from North America but rarely from European countries. They have provided a good deal of information about the persistence of ADHD and its impairments, but the degree to which these results generalize to population samples and to other countries is not certain. Prior studies have also not assessed predictors of new-onset ADHD in youth without ADHD. At baseline, 7,912 of 18 million telephone numbers were randomly selected from throughout France from October 2, 2008, through December 11, 2008. Among 4,186 eligible families, 1,012 (24.2%) were successfully recruited at baseline, when a telephone interview was administered to all families about a child in the 6- to 12-year age range. Four years later, we attempted to recruit the entire sample to assess the persistence of ADHD and its impairments and the emergence of new associated conditions. 86.5% of the families assessed at baseline were followed-up (N = 875). Participants who were and were not interviewed at follow-up did not differ on any clinical or demographic features. At follow-up, the prevalence of full or subthreshold ADHD was 65.8% for ADHD participants and 9.8% for those not having ADHD at baseline. Among the children who were not diagnosed with ADHD at baseline, 3.4% were diagnosed with ADHD at follow-up. Both the persistence of ADHD and new onsets of ADHD were significantly predicted by several baseline clinical features and by having a family history of ADHD (all P values < .05). We replicated prior predictors of ADHD's persistence and provide new data about predictors of new ADHD onsets in the population. Our data about subthreshold ADHD support a dimensional conceptualization of the disorder and address the potential clinical utility of a subthreshold diagnostic category.

Electrodermal responding predicts responses to, and may be altered by, preschool intervention for ADHD.

To evaluate electrodermal activity (EDA) as a prospective biomarker of treatment response, to determine whether patterns of EDA are altered by treatment, and to assess oppositional defiant disorder (ODD) as a possible moderator of trajectories in EDA after an empirically supported behavioral intervention for attention-deficit hyperactivity disorder (ADHD) in preschool. Nonspecific fluctuations (NSFs) in skin conductance, which index sympathetic nervous system activity, were assessed among 4-6 year old children with ADHD (n = 99) before they participated with their parents in 1 of 2 versions of the Incredible Years intervention. All were reassessed at posttreatment, and a subgroup (n = 49) were assessed again at 1-year follow-up. No difference in pretreatment NSFs was observed between ADHD participants and a group of normal control children (n = 41). Nevertheless, among those with ADHD, fewer NSFs at pretest predicted poorer treatment response on 4 of 7 externalizing outcomes. Furthermore, treatment was associated with increasing NSFs across time, but not for those who scored high on ODD at pretest. Low EDA appears to mark resistance to treatment among preschoolers with ADHD. Furthermore, although our study was not experimental, treatment was associated with longitudinal increases in EDA, which were not observed in a normal control group. This may suggest increased sensitivity to discipline, with positive implications for long term outcome. In contrast to treated participants as a whole, however, those who scored high on ODD at pretest exhibited reduced EDA over time. (PsycINFO Database Record

On-line Puzzle Game Based Assessment & Training for Adhd

Attention-deficit hyperactivity disorder (ADHD) is the most prevalent and impairing neurodevelopmental disorder, with worldwide estimates of 5.29%. ADHD is clinically characterized by hyperactivity-impulsivity and inattention, with neuropsychological deficits in executive functions, attention, working memory and inhibition. These cognitive processes rely on prefrontal cortex function; cognitive training programs enhance performance of ADHD participants supporting the idea of neuronal plasticity. Here we propose the development of an on-line puzzle game based assessment and training tool in which participants must deduce the ‘winning symbol’ out of N distracters. To increase ecological validity of assessments strategically triggered Twitter/Facebook notifications will challenge the ability to ignore distracters. In the UK, significant cost for the disorder on health, social and education services, stand at £23m a year. Thus the potential impact of neuropsychological assessment and training to improve our understanding of the pathophysiology of ADHD, and hence our treatment interventions and patient outcomes, cannot be overstated.

Affective processing bias in youth with primary bipolar disorder or primary attention-deficit/hyperactivity disorder.

High rates of comorbidity and overlapping diagnostic criteria between pediatric bipolar disorder (BD) and attention-deficit/hyperactivity disorder (ADHD) contribute to diagnostic and treatment confusion. To advance what is known about both disorders, we compared effect of emotional stimuli on response control in children with primary BD, primary ADHD and typically developing controls (TDC). Participants included 7-17 year olds with either "narrow-phenotype" pediatric BD (n = 25), ADHD (n = 25) or TDC (n = 25). Groups were matched on participant age and FSIQ. The effect of emotional stimuli on response control was assessed using the Cambridge Neuropsychological Test Automated Battery Affective Go/No-Go task (CANTAB AGN). We found a group by target valence interaction on commission errors [F(2,71) = 5.34, p < 0.01, ƞ p (2) = 0.13] whereby ADHD, but not TDC participants, made more errors on negative than positive words [t(24) = -2.58, p < 0.05, r = 0.47]. In contrast, there was a nonsignificant trend for BD participants to make fewer errors on negative versus positive words compared to ADHD and TDC participants. Between-subjects effects showed that ADHD participants made more errors than TDC, but not BD participants. Our main finding advances what is known about the effect of emotional stimuli on response control in children with ADHD. Our results suggesting a positive affective processing bias in children with ADHD compliment emerging literature show that difficulties with emotional processing and regulation may be core features of ADHD. Further, given the observed pattern of results in children with ADHD compared to BD children, our behavioral results suggest the importance of examining differences in the brain-behavior mechanisms involved in affective processing in children with ADHD compared to BD children.

The Speed of Visual Attention and Motor-Response Decisions in Adult Attention-Deficit/Hyperactivity Disorder

BackgroundAdults with attention-deficit/hyperactivity disorder (ADHD) exhibit slowed reaction times (RTs) in various attention tasks. The exact origins of this slowing, however, have not been established. Potential candidates are early sensory processes mediating the deployment of focal attention, stimulus response translation processes deciding upon the appropriate motor response, and motor processes generating the response. MethodsWe combined mental chronometry (RT) measures of adult ADHD (n = 15) and healthy control (n = 15) participants with their lateralized event-related potentials during the performance of a visual search task to differentiate potential sources of slowing at separable levels of processing: the posterior contralateral negativity (PCN) was used to index focal-attentional selection times, while the lateralized readiness potentials synchronized to stimulus and response events were used to index the times taken for response selection and production, respectively. To assess the clinical relevance of event-related potentials, a correlation analysis between neural measures and subjective current and retrospective ADHD symptom ratings was performed. ResultsADHD patients exhibited slower RTs than control participants, which were accompanied by prolonged PCN and lateralized readiness potentials synchronized to stimulus, but not lateralized readiness potentials synchronized to response events, latencies. Moreover, the PCN timing was positively correlated with ADHD symptom ratings. ConclusionsThe behavioral RT slowing of adult ADHD patients was based on a summation of internal processing delays arising at perceptual and response selection stages; motor response production, by contrast, was not impaired. The correlation between PCN times and ADHD symptom ratings suggests that this brain signal may serve as a potential candidate for a neurocognitive endophenotype of ADHD.

Cross-cultural validation of a behavioral screener for executive functions: Guidelines for clinical use among Colombian children with and without ADHD.

Garcia-Barrera, Kamphaus, and Bandalos (2011) derived a 25-item executive functioning screener from the Behavior Assessment System for Children (BASC), measuring 4 latent executive constructs: problem solving, attentional control, behavioral control, and emotional control. The current study included a cross-cultural examination of this screener in Colombian children with and without attention-deficit/hyperactivity disorder (ADHD). BASC teacher ratings were collected for Colombian children ages 6-11 years (848 healthy children [53% boys] and 155 children with ADHD [76% boys]). To examine the psychometric properties of the screener, a multistep procedure was implemented, including (a) confirmatory factor analysis (CFA) and factorial invariance testing across gender, age group (6-8 years, 9-11 years), and ADHD status to replicate and extend the original derivation; (b) item response theory (IRT) analysis to evaluate the information provided by individual items; and (c) given IRT results, a repeated CFA and invariance testing after the exclusion of 1 item from the problem-solving factor. The 24-item 4-factor model fit was adequate for controls and for ADHD participants. Results support the use of the 24-item executive functioning screener in a cross-cultural context. In turn, in supplemental material, normative data for the Colombian sample are reported along with bilingual guidelines (i.e., Spanish/English) for implementing the screener in clinical practice. Even though the screener is useful when examining executive functions, it was not designed as a diagnostic measure for developmental disorders such as ADHD; as such, it should only inform about status of executive functioning.

Behavioral and neural correlates of facial versus nonfacial stimuli processing in adults with ADHD: An ERP study.

The present study was aimed at identifying behavioral and neural correlates of face processing in adults with attention-deficit/hyperactivity disorder (ADHD) using scalp-recorded event-related potentials (ERPs). Behavioral and ERP responses were examined using a 4-stimulus visual oddball task, combining facial and nonfacial stimuli. Responses to target and nontarget stimuli were compared across groups of young adults with ADHD and comparison subjects. Participants with ADHD had poorer performance than controls on all indices of the oddball task. Higher rates of omissions and slower reaction times (RTs) of ADHD participants compared with controls had been found only in response to face targets but not in response to nonfacial targets. ERP results indicated that ADHD significantly interacted with the type of target stimuli. Participants with ADHD, compared with controls, showed a pronounced reduction in P3 and N3 amplitudes in response to face targets but not in response to nonfacial targets. The current results provide indication of modulation of face processing in adults with ADHD. ERP alterations, reflected in abnormally reduced P3 and N3 to face targets, may suggest ADHD-related abnormal recruitment of neural resources to process face stimuli. Behavioral and brain function measures of face processing may provide valuable additional tools for use in clinical assessment of ADHD in adulthood.

Variability of kinematic graphomotor fluency in adults with ADHD

Although graphomotor differences and variability of performance have been observed in children with attention deficit hyperactivity disorder (ADHD), no study has investigated whether this variability manifests in the kinematic graphomotor domain in adults with ADHD. Fourteen ADHD and 20 control participants wrote a novel grapheme and common word on a digitizing tablet 30 times each, with ADHD participants counterbalanced on and off stimulant medication. Variability of graphomotor fluency was significantly greater in ADHD versus control participants only in the novel writing task, both on, F(1,31)=5.988, p=.020, and off stimulant medication, F(1,32)=8.789, p=.006. Results suggest that motor control differences in ADHD are not limited to childhood and extend into adulthood. Given sufficient additional research, variability of kinematic graphomotor fluency may increase the sensitivity/specificity of differential diagnoses and/or represent a biomarker for ADHD.

Distinct regions of the cerebellum show gray matter decreases in autism, ADHD, and developmental dyslexia.

Differences in cerebellar structure have been identified in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and developmental dyslexia. However, it is not clear if different cerebellar regions are involved in each disorder, and thus whether cerebellar anatomical differences reflect a generic developmental vulnerability or disorder-specific characteristics. To clarify this, we conducted an anatomic likelihood estimate (ALE) meta-analysis on voxel-based morphometry (VBM) studies which compared ASD (17 studies), ADHD (10 studies), and dyslexic (10 studies) participants with age-matched typically-developing (TD) controls. A second ALE analysis included studies in which the cerebellum was a region of interest (ROI). There were no regions of significantly increased gray matter (GM) in the cerebellum in ASD, ADHD, or dyslexia. Data from ASD studies revealed reduced GM in the inferior cerebellar vermis (lobule IX), left lobule VIIIB, and right Crus I. In ADHD, significantly decreased GM was found bilaterally in lobule IX, whereas participants with developmental dyslexia showed GM decreases in left lobule VI. There was no overlap between the cerebellar clusters identified in each disorder. We evaluated the functional significance of the regions revealed in both whole-brain and cerebellar ROI ALE analyses using Buckner and colleagues' 7-network functional connectivity map available in the SUIT cerebellar atlas. The cerebellar regions identified in ASD showed functional connectivity with frontoparietal, default mode, somatomotor, and limbic networks; in ADHD, the clusters were part of dorsal and ventral attention networks; and in dyslexia, the clusters involved ventral attention, frontoparietal, and default mode networks. The results suggest that different cerebellar regions are affected in ASD, ADHD, and dyslexia, and these cerebellar regions participate in functional networks that are consistent with the characteristic symptoms of each disorder.

Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study

There is increasing evidence that abnormalities in glutamate signalling may contribute to the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectroscopy ([1H]MRS) can be used to measure glutamate, and also its metabolite glutamine, in vivo. However, few studies have investigated glutamate in the brain of adults with ADHD naive to stimulant medication. Therefore, we used [1H]MRS to measure the combined signal of glutamate and glutamine (Glu+Gln; abbreviated as Glx) along with other neurometabolites such as creatine (Cr), N-acetylaspartate (NAA) and choline. Data were acquired from three brain regions, including two implicated in ADHD—the basal ganglia (caudate/striatum) and the dorsolateral prefrontal cortex (DLPFC)—and one ‘control' region—the medial parietal cortex. We compared 40 adults with ADHD, of whom 24 were naive for ADHD medication, whereas 16 were currently on stimulants, against 20 age, sex and IQ-matched healthy controls. We found that compared with controls, adult ADHD participants had a significantly lower concentration of Glx, Cr and NAA in the basal ganglia and Cr in the DLPFC, after correction for multiple comparisons. There were no differences between stimulant-treated and treatment-naive ADHD participants. In people with untreated ADHD, lower basal ganglia Glx was significantly associated with more severe symptoms of inattention. There were no significant differences in the parietal ‘control' region. We suggest that subcortical glutamate and glutamine have a modulatory role in ADHD adults; and that differences in glutamate–glutamine levels are not explained by use of stimulant medication.