A preliminary neuroimaging study of preschool children with ADHD

A preliminary investigation into cortical structural alterations in adolescents with nonsuicidal self-injury

The structural neural correlates underlying youth nonsuicidal self-injury (NSSI) warrant further exploration. Few studies have explored the association between NSSI and brain structure in adolescence, and no studies have investigated differences in the relation between age and brain structure in youth with NSSI. This preliminary investigation examined associations between NSSI history, age, and cortical structure using magnetic resonance imaging in adolescent girls (N=100, Mage=13.4 years) at increased risk for psychopathology. We conducted whole-brain analyses to investigate the associations between age and cortical structure, NSSI history and cortical structure, and NSSI history as a moderator of the association between age and cortical structure. Results suggested that age was associated with less cortical thickness and surface area in the left and right prefrontal, temporal, and parietal cortex. NSSI history was associated with less left insula and left inferior parietal cortex cortical surface area. Among adolescents with NSSI history, older age predicted greater left inferior parietal cortex surface area and was not associated with left precentral cortex surface area. Among adolescents without NSSI history, older age predicted smaller surface areas as expected with the typical trajectory of neurodevelopment. Overall, our results suggest differences in cortical surface area development in adolescents with NSSI history.

Screen Time and ADHD Behaviors in Chinese Children: Findings From Longitudinal and Cross-Sectional Data

OBJECTIVE

Research suggests that screen exposure presents a risk for ADHD behaviors in young children. However, the operationalization of screen exposure remains murky and longitudinal data is scarce. In this paper, we examined the relations between better operationalized daily screen time and behaviors of inattention and behaviors of hyperactivity/impulsivity in three cohorts of community samples of young Chinese children.

METHOD

Study 1 was longitudinal and included 111 children who were 3.6 years old (Range = 2.4-4.9; SD = 0.4) at Baseline and 4.8 years old (Range = 3.9-6.0; SD = 0.4) at Follow-Up. Study 2 was cross-sectional and included 172 children aged 4.9 years (Range = 3.0-7.1; SD = 1.0). Study 3 was also cross-sectional and included 313 children who were 6.9 years old (Range = 5.7-8.3; SD = 0.4). In each study, the parents reported how much time that their children spent daily on iPad/tablet, smart phone, and online games and watching TV in the previous week, and their children's behaviors of inattention (I/A) and hyperactivity/impulsivity (H/I).

RESULTS

Regression analysis revealed that in Study 1, controlling for child demographics, mother's education, family SES, and corresponding I/A or H/I scores at Baseline, screen time at Baseline predicted I/A scores (β = .27, p < .01) and H/I scores (β = .32, p < .001) at Follow-Up. Similarly, controlling for covariates, screen time predicted I/A scores (β = .25, p < .01) and H/I scores (β = .25, p < .01) in Study 2; I/A scores (β = 0.16, p < .01) and H/I scores (β = .15, p < .05) in Study 3.

CONCLUSION

Screen exposure was a risk for inattention and hyperactivity/impulsivity behaviors in urban Chinese children.

Systematic Review and Meta-analysis: The Science of Early-Life Precursors and Interventions for Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

To evaluate which early neurocognitive and behavioral precursors are associated with the development of attention-deficit/hyperactivity disorder (ADHD) and whether these are currently targeted in early interventions.

METHOD

We conducted 2 systematic reviews and meta-analyses of empirical studies to examine the following: (1) early-life (0-5 years) neurocognitive and behavioral precursors associated with familial likelihood for ADHD, an early ADHD diagnosis/elevated ADHD symptoms, and/or the presence of later-childhood ADHD; and (2) interventions delivered to children aged 0 to 5 years targeting the identified precursors or measuring these as outcomes. Standardized mean differences (Hedges' g) and pre-post-treatment change scores (SMD) were computed.

RESULTS

A total of 149 studies (165,095 participants) investigating 8 neurocognitive and behavioral domains met inclusion criteria for part 1. Multi-level random-effects meta-analyses on 136 studies revealed significant associations between ADHD and poorer cognitive (g = -0.46 [95% CIs: -0.59, -0.33]), motor (g = -0.35 [CIs: -0.48, -0.21]) and language (g = -0.43 [CIs: -0.66, -0.19]) development, social (g = 0.23 [CIs: 0.03, 0.43]) and emotional (g = 0.46 [CIs: 0.33, 0.58]) difficulties, early regulatory (g = 0.30 [CIs: 0.18, 0.43]) and sleep (g = 0.29 [CIs: 0.14, 0.44]) problems, sensory atypicalities (g = 0.52 [CIs: 0.16, 0.88]), elevated activity levels (g = 0.54 [CIs: 0.37, 0.72]), and executive function difficulties (g = 0.34 [CIs: 0.05, 0.64] to -0.87 [CIs: -1.35, -0.40]). A total of 32 trials (28 randomized, 4 nonrandomized, 3,848 participants) testing early interventions that targeted the identified precursors met inclusion criteria for part 2. Multi-level random-effects meta-analyses on 22 studies revealed significant intervention-related improvements in ADHD symptoms (SMD = 0.43 [CIs: 0.22, 0.64]) and working memory (SMD = 0.37 [CIs: 0.06, 0.69]).

CONCLUSION

Children aged 0 to 5 years with current or later-emerging ADHD are likely to experience difficulties in multiple neurocognitive/behavioral functions. Early interventions show some effectiveness in reducing ADHD symptoms, but their effects on neurocognitive/behavioral difficulties require further study.

Registration-free analysis of diffusion MRI tractography data across subjects through the human lifespan

Diffusion MRI tractography produces massive sets of streamlines that need to be clustered into anatomically meaningful white-matter bundles. Conventional clustering techniques group streamlines based on their proximity in Euclidean space. We have developed AnatomiCuts, an unsupervised method for clustering tractography streamlines based on their neighboring anatomical structures, rather than their coordinates in Euclidean space. In this work, we show that the anatomical similarity metric used in AnatomiCuts can be extended to find corresponding clusters across subjects and across hemispheres, without inter-subject or inter-hemispheric registration. Our proposed approach enables group-wise tract cluster analysis, as well as studies of hemispheric asymmetry. We evaluate our approach on data from the pilot MGH-Harvard-USC Lifespan Human Connectome project, showing improved correspondence in tract clusters across 184 subjects aged 8-90. Our method shows up to 38% improvement in the overlap of corresponding clusters when comparing subjects with large age differences. The techniques presented here do not require registration to a template and can thus be applied to populations with large inter-subject variability, e.g., due to brain development, aging, or neurological disorders.

Attention-deficit/hyperactivity disorder in elite athletes: a narrative review

Attention-deficit/hyperactivity disorder (ADHD) is a common brain developmental disorder in the general population that may be even more prevalent in elite athletes in certain sports. General population studies of ADHD are extensive and have reported on prevalence, symptoms, therapeutic and adverse effects of treatment and new clinical and research findings. However, few studies have reported on prevalence, symptoms and treatments of ADHD in elite athletes. This narrative review summarises the literature on symptoms, comorbidities, effects of ADHD on performance and management options for elite athletes with ADHD. The prevalence of ADHD in student athletes and elite athletes may be 7%–8%. The symptoms and characteristics of ADHD play a role in athletes’ choice of a sport career and further achieving elite status. Proper management of ADHD in elite athletes is important for safety and performance, and options include pharmacologic and psychosocial treatments.

Anomalous Brain Development Is Evident in Preschoolers With Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

Attention-deficit/hyperactivity disorder (ADHD) is a common neurological disorder with symptom onset early in childhood. Growing evidence suggests anomalous brain development across multiple brain regions is evident in school-aged children; however, few studies have examined whether such differences are notable in the preschool years when symptom onset typically occurs.

METHODS

High resolution anatomical (MPRAGE) images and cognitive and behavioral measures were analyzed in a total of 90 medication-naïve preschoolers, ages 4-5 years (52 with ADHD, 38 controls; 64.4% boys).

RESULTS

Results revealed reductions in bilateral frontal, parietal, and temporal lobe gray matter volumes in children with ADHD relative to typically developing children, with largest effect sizes noted for right frontal and left temporal lobe volumes. Examining frontal lobe sub-regions, the largest between group effect sizes were evident for left orbitofrontal cortex, left primary motor cortex (M1), and left supplementary motor complex (SMC). ADHD-related reductions in specific sub-regions (left prefrontal, left premotor, left frontal eye field, left M1, and right SMC) were significantly correlated with symptom severity, such that higher ratings of hyperactive/impulsive symptoms were associated with reduced cortical volumes.

CONCLUSIONS

These findings represent the first comprehensive examination of cortical volume in preschool children with ADHD, providing evidence that anomalous brain structure in ADHD is evident very early in development. Furthermore, findings set the stage for developing our understanding of the way in which developmental trajectories of anomalous brain development are associated with the unfolding of symptoms in childhood ADHD. (JINS, 2018, 24, 531-539).

Hyperactivity in motor response inhibition networks in unmedicated children with attention deficit-hyperactivity disorder

OBJECTIVES

Hypo/reduced activity in motor response inhibition (RI) cerebral networks was recently proposed as a promising specific neurobiological marker of attention deficit-hyperactivity disorder (ADHD). Before adopting such a pattern as a key diagnosis tool, we aim to replicate in an independent study the mechanisms underlying reduced RI-related activity in ADHD, after controlling for potentially confounding effects.

METHODS

In this fMRI study, we investigated the neural networks mediating successful and failed motor RI in children with ADHD and typically developing children (TDC) using the stop-signal task (SST) paradigm.

RESULTS

In contrast to hypofrontality predictions, children with ADHD exhibit increased neural activity during successful response inhibition in an RI-related brain network encompassing the indirect and/or hyperdirect pathways between the basal ganglia and cortex. Voxel-based morphometry analyses have further evidenced reduced grey matter volume in the left caudate in children with ADHD, which paralleled higher functional responses. Finally, connectivity analyses disclosed tighter coupling between a set of cortical regions and the right caudate as well as the right IFG, networks involved in successful RI.

CONCLUSIONS

Hypo/reduced activity in RI cerebral networks in children with ADHD cannot at this time be considered as a systematic biomarker for ADHD.

Reduced subcortical volumes among preschool-age girls and boys with ADHD

Anomalous brain structure and function are implicated in children with attention-deficit/hyperactivity disorder (ADHD). Most neuroimaging research, however, has examined school-aged children, despite the typical onset of symptoms in early childhood. This study compared the volumes of subcortical structures (caudate nucleus, putamen, globus pallidus, and thalamus) among preschoolers with ADHD and typically developing (TD) children. High resolution T1-weighted 3D MPRAGE images covering the whole brain were acquired on a 3T scanner and subcortical volumes were automatically extracted. Analyses were conducted in a total of 87 medication-naïve preschoolers, ages 4-5 years (47 with ADHD, 40 controls; 63% boys). ADHD was diagnosed using modified DSM-IV criteria based on review of developmental history, structured psychiatric interview and caregiver ratings. Compared to typically developing children, subcortical volumes were reduced among preschoolers with ADHD, with largest reductions in the caudate, globus pallidus, and thalamus. Among girls (but not boys) with ADHD, putamen and thalamus volumes were associated with ADHD symptom severity. The observed patterns of subcortical differences in preschoolers with ADHD (larger reductions in girls), contrasted with differences observed among school-aged children, (larger reductions in boys) suggests that children with ADHD show sexual dimorphism in neuroanatomical development that parallels early trajectory of symptom onset and attenuation.

How neuropsychology can inform our understanding of preschool ADHD: Clinical and research implications

Neuropsychological assessments in preschoolers have not received as much attention as in older children and adults. Attention-deficit/hyperactivity disorder (ADHD) is a common disorder that occurs in early childhood associated with poor academic and personal outcomes, such as learning and social difficulties. Preschoolers with ADHD may present cognitive deficits that are related with the ADHD symptoms of inattention, hyperactivity, and impulsivity, but may also interfere, beyond and above the ADHD symptoms, with everyday functioning. Most importantly, cognitive deficits in preschoolers seem to predict future ADHD symptoms. Yet, the practice of neuropsychological assessment in this age-group has been limited. The present selective review highlights the contribution of comprehensive neuropsychological assessments to the early identification of symptomatic preschoolers and to our understanding of the nature and developmental trajectory of ADHD.

Attention-Deficit/Hyperactivity Disorder: A Historical Neuropsychological Perspective

The behavior patterns of hyperactivity, impulsivity and inattention that would ultimately become recognized as Attention-Deficit Hyperactivity Disorder (ADHD) have been described for centuries. Nevertheless, in the past 35 years, advances in diagnostic methods, identification of biomarkers, and treatments have advanced at an exponential rate. ADHD is now recognized as the most common behavioral disorder of childhood, with risks extending well into adulthood for both males and females, leading to its identification as a significant public health issue. This historical neuropsychological review of ADHD emphasizes scientific highlights in the past 35 years related to ADHD, including the evolution of the diagnosis (from Hyperkinetic Reaction of Childhood to ADHD), influential theories (executive functions, cognitive-energetic, delay aversion), landmark treatment studies (Multimodal Treatment of ADHD [MTA] and Preschool ADHD Treatment Study [PATS]), and advances in brain mapping techniques (anatomic, functional, and resting state magnetic resonance imaging, diffusion tensor imaging). The review concludes by highlighting the challenges of studying and treating a heterogeneous neurodevelopmental disorder like ADHD, with emphasis on associated disorders and conditions (learning disabilities, sluggish cognitive tempo), special populations (girls, preschoolers, adults), and recommendations for scientific inquiry in the next 35 years. Neuropsychologists are well positioned to address the clinical and research challenges of the next generation of studies, especially involving advances in understanding the sexual dimor.phism, full developmental course, and dynamic risks associated with ADHD. (JINS, 2017, 23, 916-929).

Contralateral Associated Movements Correlate with Poorer Inhibitory Control, Attention and Visual Perception in Preschool Children

Contralateral associated movements (CAMs) frequently occur in complex motor tasks. We investigated whether and to what extent CAMs are associated with inhibitory control among preschool children in the Swiss Preschoolers' Health Study. Participants were 476 healthy, typically developing children (mean age = 3.88 years; 251 boys) evaluated on two consecutive afternoons. The children performed the Zurich Neuromotor Assessment, the statue subtest of the Neuropsychological Assessment for Children (NEPSY), and cognitive tests of the Intelligence and Development Scales-Preschool (IDS-P). CAMs were associated with poor inhibitory control on the statue test and poor selective attention and visual perception on the IDS-P. We attributed these findings to preschoolers' general immaturity of the central nervous system.

Iranian Children With ADHD and Mental Health of Their Mothers: The Role of Stress

BACKGROUND

Attention deficit/hyperactivity disorder (ADHD) is a psychiatric disorder that can result in stress for the mother, resulting in poor health.

OBJECTIVES

The current study, conducted in 2012, aims to assess stress among forty-six Iranian mothers of ADHD children (Group 1) who were admitted to a psychiatric center in Tehran with forty-six Iranian mothers of normal children (Group 2) in 2012.

MATERIALS AND METHODS

The Child Symptom Inventory-4 (CSI-4), the child behavior checklist (CBCL) and the parental stress index-short form (PSI/SF) were completed. Data was analyzed using the Levene test and the independent t-test in SPSS Version 18.

RESULTS

With the exception of mood, ADHD children had more problems in attention compared with normal children. As a result, mothers of ADHD children had more stress compared with the controls.

CONCLUSIONS

ADHD can impair a mother's mental health by inducing stress. Specific diagnostic and treatment programs should be designed and tailored for the mothers of ADHD children in order to decrease stress.

Attention Deficit Hyper Activity Disorder (ADHD) and Stress: A Mutual Relationship between Children and Mothers

INTRODUCTION

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by high levels of inattention, hyperactivity and impulsivity which may result in mothers' stress. The current study aims to compare stress among 45 mothers of ADHD children who had referred to "Rofeydeh psychiatric center" with 45 mothers of normal children.

METHODS

Brief demographic researcher-made questionnaire, Child Symptom Inventory-4 (CSI-4), the Child Behavior Checklist (CBCL), and Parental Stress Index-Short Form (PSI/SF) were completed for each mother and child.

RESULTS

The results showed that except the component of acceptance, ADHD children had more problems in the field of attention compared with normal children. Mothers of ADHD children had also more stress compared with mothers of normal children.

DISCUSSION

ADHD can impair mothers' mental health by inducing stress and this issue has important clinical and treatment implications. Specific treatment programs should be designed and implemented in Iran for the mothers of ADHD children to reduce stress among them and therefore, improve their mental health status.

Structural correlates of COMT Val158Met polymorphism in childhood ADHD: a voxel-based morphometry study

OBJECTIVES

The Val158-allele of the catechol-O-methyltransferase (COMT) Val158Met (rs4680) functional polymorphism has been identified as a risk factor for antisocial behaviour in attention-deficit/hyperactivity disorder (ADHD). Here, we used voxel-based morphometry to investigate the effects of Val158Met polymorphism on grey matter (GM) volumes in a sample of 7-13-year-old children.

METHODS

MRI and genotype data were obtained for 38 children with combined-type ADHD and 24 typically developing (TD) children. Four regions of interest were identified: striatum, cerebellum, temporal lobe and inferior frontal gyrus (IFG).

RESULTS

When compared to TD children, those with ADHD had a significant decrease of GM volume in the IFG. Volume in this region was negatively correlated with ratings of hyperactivity/impulsivity symptoms. Furthermore, the smaller GM volume in the IFG was attributed to the presence of the Met158-allele, as only children with ADHD carrying a Met158-allele exhibited such decrease in the IFG. Children with ADHD homozygotes for the Val158-allele presented increased GM volume in the caudate nucleus when compared with TD children.

CONCLUSIONS

This study provides the first evidence of a modulation of ADHD-related GM volume alterations by Val158Met in two key regions, possibly mediating the relationship between Val158Met polymorphism and antisocial behaviour in children with ADHD.

The four causes of ADHD: a framework

In addition to the symptoms singled out by the diagnostic criteria for Attention-Deficit Hyperactivity Disorder (ADHD), a comprehensive definition should inform us of the events that trigger ADHD in both its acute and chronic manifestations; the neurobiology that underlies it; and the evolutionary forces that have kept it in the germ line of our species. These factors are organized in terms of Aristotle's four kinds of "causes," or explanations: formal, efficient, material, and final. This framework systematizes the nosology, biology, psychology, and evolutionary pressures that cause ADHD.

Multimodal magnetic resonance imaging study of treatment-naïve adults with attention-deficit/hyperactivity disorder

Background

Attention-Deficit/Hiperactivity Disorder (ADHD) is a prevalent disorder, but its neuroanatomical circuitry is still relatively understudied, especially in the adult population. The few morphometric magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) studies available to date have found heterogeneous results. This may be at least partly attributable to some well-known technical limitations of the conventional voxel-based methods usually employed to analyze such neuroimaging data. Moreover, there is a great paucity of imaging studies of adult ADHD to date that have excluded patients with history of use of stimulant medication.

Methods

A newly validated method named optimally-discriminative voxel-based analysis (ODVBA) was applied to multimodal (structural and DTI) MRI data acquired from 22 treatment-naïve ADHD adults and 19 age- and gender-matched healthy controls (HC).

Results

Regarding DTI data, we found higher fractional anisotropy in ADHD relative to HC encompassing the white matter (WM) of the bilateral superior frontal gyrus, right middle frontal left gyrus, left postcentral gyrus, bilateral cingulate gyrus, bilateral middle temporal gyrus and right superior temporal gyrus; reductions in trace (a measure of diffusivity) in ADHD relative to HC were also found in fronto-striatal-parieto-occipital circuits, including the right superior frontal gyrus and bilateral middle frontal gyrus, right precentral gyrus, left middle occipital gyrus and bilateral cingulate gyrus, as well as the left body and right splenium of the corpus callosum, right superior corona radiata, and right superior longitudinal and fronto-occipital fasciculi. Volumetric abnormalities in ADHD subjects were found only at a trend level of significance, including reduced gray matter (GM) in the right angular gyrus, and increased GM in the right supplementary motor area and superior frontal gyrus.

Conclusions

Our results suggest that adult ADHD is associated with neuroanatomical abnormalities mainly affecting the WM microstructure in fronto-parieto-temporal circuits that have been implicated in cognitive, emotional and visuomotor processes.

Striatal volume deficits in children with ADHD who present a poor response to methylphenidate

Methylphenidate (MPH) is the first choice of medical treatment for attention-deficit/hyperactivity disorder (ADHD). Its mechanism of action is to inhibit the reuptake of dopamine and noradrenaline mainly in the region of the striatum. It has been estimated that 10-30 % of patients with ADHD do not respond adequately to MPH. The aim of this study was to evaluate whether striatal differences exist between good and poor responders to MPH. The sample included 27 treatment-naïve children with ADHD between the ages of 6 and 14. MPH administration started 1 day after the MRI acquisition. After a month, psychiatrists established the good or poor response to treatment according to clinical criteria. MRI images were analyzed using a technique based on regions of interest applied specifically to the caudate and accumbens nuclei. Sixteen patients showed good response to MPH and 11 a poor one. Regions of interest analysis showed that good responders had a higher concentration of gray matter in the head of both caudate nuclei and the right nucleus accumbens. Furthermore, a significant correlation was found between caudate and accumbens nuclei volume and the Conners' Parent Rating Scale and Continuous Performance Test improvement. These results support the hypothesis of the involvement of the caudate and accumbens nuclei in MPH response and in ADHD pathophysiology.

Sex differences and the interaction of age and sleep issues in neuropsychological testing performance across the lifespan in an ADD/ADHD sample from the years 1989 to 2009

Chart review of population (9 to 80 years) neuropsychological test battery for ADHD diagnosis, questionnaires with multiple responders were evaluated in outpatient setting from 1989-2009. The focus was gender differences across age, diagnostic group (ADHD-Inattentive/ADHD plus), neuropsychological test performance, and reported sleep symptoms over the lifespan. Individuals were assigned to ADHD-I group or ADHD plus group (based upon secondary diagnosis of sleep, behavioral, emotional disturbance); ADHD not primary was excluded (brain insult, psychosis). Among these were 1,828 children (ages 9 to 14), adolescents (ages 15 to 17), and adults (ages 18 and above); 446 children (312 diagnosed ADHD-I), 218 adolescents (163 diagnosed ADHD-I), and 1,163 adults (877 ADHD-I). Sleep was problematic regardless of age, ADHD subtype, and gender. The type and number of sleep problems and fatigue were age dependent. ADHD subtype, gender, fatigue, age, and sleep (sleep onset, unrefreshing sleep, sleep maintenance) were significant variables affecting neuropsychological test performance (sequencing, cognitive flexibility, slow- and fast-paced input, divided attention, whole brain functioning). Findings suggest that ADHD involves numerous factors and symptoms beyond attention, such as sleep which interacts differently dependent upon age.

The neurobiological link between OCD and ADHD

Obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are two of the most common neuropsychiatric diseases in paediatric populations. The high comorbidity of ADHD and OCD with each other, especially of ADHD in paediatric OCD, is well described. OCD and ADHD often follow a chronic course with persistent rates of at least 40–50 %. Family studies showed high heritability in ADHD and OCD, and some genetic findings showed similar variants for both disorders of the same pathogenetic mechanisms, whereas other genetic findings may differentiate between ADHD and OCD. Neuropsychological and neuroimaging studies suggest that partly similar executive functions are affected in both disorders. The deficits in the corresponding brain networks may be responsible for the perseverative, compulsive symptoms in OCD but also for the disinhibited and impulsive symptoms characterizing ADHD. This article reviews the current literature of neuroimaging, neurochemical circuitry, neuropsychological and genetic findings considering similarities as well as differences between OCD and ADHD.

Neuroimaging of attention-deficit/hyperactivity disorder: current neuroscience-informed perspectives for clinicians

The neuroimaging literature on attention-deficit/hyperactivity disorder (ADHD) is growing rapidly. Here, we provide a critical overview of neuroimaging studies published recently, highlighting perspectives that may be of relevance for clinicians. After a comprehensive search of PubMed, Ovid, Web of Science, and EMBASE, we located 41 pertinent papers published between January 2011 and April 2012, comprising both structural and functional neuroimaging studies. This literature is increasingly contributing to the notion that the pathophysiology of ADHD reflects abnormal interplay among large-scale brain circuits. Moreover, recent studies have begun to reveal the mechanisms of action of pharmacological treatment. Finally, imaging studies with a developmental perspective are revealing the brain correlates of ADHD over the lifespan, complementing clinical observations on the phenotypic continuity and discontinuity of the disorder. However, despite the increasing potential to eventually inform clinical practice, current imaging studies do not have validated applications in day-to-day clinical practice. Although novel analytical techniques are likely to accelerate the pace of translational applications, at the present we advise caution regarding inappropriate commercial misuse of imaging techniques in ADHD.

Smaller volumes of caudate nuclei in prepubertal children with ADHD: impact of age

OBJECTIVE

Age-related abnormalities in caudate volumes have been reported to differ across the periods of childhood and puberty in children with ADHD. This study assessed caudate volumetric abnormalities across two narrow age clusters within the childhood period.

METHOD

Three-dimensional manual tracings of the head and body of the caudate nucleus and of the cerebrum were acquired from 26 medication-naïve boys with a diagnosis of ADHD (ages 5.9-10.8 years), and 24 age-matched normal controls.

RESULTS

Boys with ADHD had smaller total caudate volumes relative to controls, F(1,48)=4.29, p=0.04. Adjustment of caudate volumes with respect to age demonstrated that this group difference was driven solely by participants in the 5.9-7.3 year range, F(1, 46)=5.64, p=0.022, with an effect size of d=0.69. No Group effect was found in older participants, F(1, 46)=0.82, p=0.37.

CONCLUSIONS

These novel findings suggest a different pattern of caudate volume abnormalities across narrow age clusters prior to puberty in boys with ADHD. Anatomical differences in brain structures related to ADHD in prepubertal children should be evaluated with respect to the changing developmental trajectory of brain regions within this period of rapid brain growth.

ADHD: volumetry, motor, and oculomotor functions

The use of quantitative neuroimaging (volumetry), motor, and oculomotor assessments for studying children with attention-deficit/hyperactivity disorder (ADHD) has grown dramatically in the past 20 years. Most evidence to date suggests that anomalous basal ganglia development plays an important role in early manifestation of ADHD; however, widespread cerebellar and cortical delays are also observed and are associated with the behavioral (cognitive, motor, oculomotor) phenotype in children with ADHD. These motor and "executive" control systems appear to develop in parallel, such that both systems display a similar protracted developmental trajectory, with periods of rapid growth in elementary years and continued maturation into young adulthood. Development of each system is dependent on the functional integrity and maturation of related brain regions, suggesting a shared neural circuitry that includes frontostriatal systems and the cerebellum (i.e., those identified as anomalous in studies of volumetry in ADHD). Motor and oculomotor paradigms provide unique opportunities to examine executive control processes that exist at the interface between movement and cognition in children with ADHD, also linking cognition and neurological development. The observed pattern of volumetric differences, together with the known parallel development of motor and executive control systems, appears to predict motor and oculomotor anomalies in ADHD, which are highly relevant, yet commonly overlooked in clinical settings.