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

Abnormal Structure and Function of Parietal Lobe in Individuals With Attention Deficit Hyperactivity Disorder (ADHD): A Systematic Review Study

Introduction

Abnormal brain structure and function have been reported in individuals with attention deficit hyperactivity disorder (ADHD). This study investigated the parietal lobe structure and function alteration in individuals with ADHD.

Methods

In this systematic review, we searched English papers in accordance with the PRISMA (the preferred reporting items for systematic reviews and meta-analyses) approach. Studies were published between January 2010 and May 2021. Our search was conducted in two parts. Our first search was in July 2020, and our final search was in June 2021. A literature search identified 20 empirical experiments.

Results

Functional magnetic resonance imaging (MRI) studies generally reported low activity and poor connectivity; structural MRI studies reported less gray matter in this lobe, and an echo study reported atrophy. In addition, electroencephalographic studies reported less connectivity of the parietal lobes in ADHD. Furthermore, the transcranial direct current stimulation intervention has shown that activation of this lobe improves attention and executive functions in children with ADHD. Finally, a deep transcranial magnetic stimulation study has demonstrated that activation of this lobe improves working memory.

Conclusion

Functional and structural alteration of the parietal cortex has been reported in ADHD, which has a causal relationship with cognitive impairments. In sum, all included studies reported abnormal structure, function, or connectivity of the parietal lobe or improvement of cognitive functions with parietal lobe stimulation.

Male-specific, replicable and functional roles of genetic variants and cerebral gray matter volumes in ADHD: a gene-wide association study across KTN1 and a region-wide functional validation across brain

Attention deficit hyperactivity disorder (ADHD) is associated with reduction of cortical and subcortical gray matter volumes (GMVs). The kinectin 1 gene (KTN1) has recently been reported to significantly regulate GMVs and ADHD risk. In this study, we aimed to identify sex-specific, replicable risk KTN1 alleles for ADHD and to explore their regulatory effects on mRNA expression and cortical and subcortical GMVs. We examined a total of 1020 KTN1 SNPs in one discovery sample (ABCD cohort: 5573 males and 5082 females) and three independent replication European samples (Samples #1 and #2 each with 802/122 and 472/141 male/female offspring with ADHD; and Sample #3 with 14,154/4945 ADHD and 17,948/16,246 healthy males/females) to identify replicable associations within each sex. We examined the regulatory effects of ADHD-risk alleles on the KTN1 mRNA expression in two European brain cohorts (n = 348), total intracranial volume (TIV) in 46 European cohorts (n = 18,713) and the ABCD cohort, as well as the GMVs of seven subcortical structures in 50 European cohorts (n = 38,258) and of 118 cortical and subcortical regions in the ABCD cohort. We found that four KTN1 variants significantly regulated the risk of ADHD with the same direction of effect in males across discovery and replication samples (0.003 ≤ p ≤ 0.041), but none in females. All four ADHD-risk alleles significantly decreased KTN1 mRNA expression in all brain regions examined (1.2 × 10^-5 ≤ p ≤ 0.039). The ADHD-risk alleles significantly increased basal ganglia (2.8 × 10^-22 ≤ p ≤ 0.040) and hippocampus (p = 0.010) GMVs but reduced amygdala GMV (p = 0.030) and TIV (0.010 < p ≤ 0.013). The ADHD-risk alleles also significantly reduced some cortical (right superior temporal pole, right rectus) and cerebellar but increased other cortical (0.007 ≤ p ≤ 0.050) GMVs. To conclude, we identified a set of replicable and functional risk KTN1 alleles for ADHD, specifically in males. KTN1 may play a critical role in the pathogenesis of ADHD, and the reduction of specific cortical and subcortical, including amygdalar but not basal ganglia or hippocampal, GMVs may serve as a neural marker of the genetic effects.

Do Children with Attention Deficit and Hyperactivity Disorder Present with Different Spatio-Temporal Gait Parameters? An Evaluation of the Relationship Between Gait and Gross Motor Skills

Objective

The aim of the current study was to compare the spatio-temporal parameters of gait and gross motor skills in children with attention deficit hyperactivity disorder-combined type with those of typically developing children and to search the effect of motor skills on gait parameters in children with attention deficit hyperactivity disorder-combined type.

Methods

A total of 50 children (n = 25 attention deficit hyperactivity disorder-combined type, n = 25 typically developing children) aged 5-12 years were included. Gross motor skills were evaluated using the Bruininks-Oseretsky Test Second Edition-Short Form. Spatio-temporal parameters of gait were assessed with a GAITRite^® computer-based system.

Results

In the subtests of Bruininks-Oseretsky Test Second Edition-Short Form (bilateral coordination (P < .001), balance (P = .013), running speed and agility (P = .003)), lower scores were obtained by the children with attention deficit hyperactivity disorder-combined type. The swing phase of gait was found to be longer in children with attention deficit hyperactivity disorder-combined type (P = .01).

Conclusion

The current study results show that gross motor skills are affected negatively and the swing phase is prolonged in children with attention deficit hyperactivity disorder-combined type. Upper limb coordination and balance were also seen to have an effect on the velocity, step, and stride length. It is important to include an objective gait assessment as well as gross motor skills in the comprehensive clinical evaluation of children with attention deficit hyperactivity disorder-combined type.

Structural and diffusion-weighted brain imaging predictors of attention-deficit/hyperactivity disorder and its symptomology in very young (4- to 7-year-old) children

The current study aimed to identify the key neurobiology of attention-deficit/hyperactivity disorder (ADHD), as it relates to ADHD diagnostic category and symptoms of hyperactive/impulsive behaviour and inattention. To do so, we adapted a predictive modelling approach to identify the key structural and diffusion-weighted brain imaging measures and their relative standing with respect to teacher ratings of executive function (EF) (measured by the Metacognition Index of the Behavior Rating Inventory of Executive Function [BRIEF]) and negativity and emotion regulation (ER) (measured by the Emotion Regulation Checklist [ERC]), in a critical young age range (ages 4 to 7, mean age 5.52 years, 82.2% Hispanic/Latino), where initial contact with educators and clinicians typically take place. Teacher ratings of EF and ER were predictive of both ADHD diagnostic category and symptoms of hyperactive/impulsive behaviour and inattention. Among the neural measures evaluated, the current study identified the critical importance of the largely understudied diffusion-weighted imaging measures for the underlying neurobiology of ADHD and its associated symptomology. Specifically, our analyses implicated the inferior frontal gyrus as a critical predictor of ADHD diagnostic category and its associated symptomology, above and beyond teacher ratings of EF and ER. Collectively, the current set of findings have implications for theories of ADHD, the relative utility of neurobiological measures with respect to teacher ratings of EF and ER, and the developmental trajectory of its underlying neurobiology.

Childhood symptoms of attention-deficit/hyperactivity disorder and borderline personality disorder

OBJECTIVE

Childhood attention-deficit /hyperactivity disorder (ADHD) is known to be associated with adult Borderline Personality Disorder (BPD). We investigated if any of the subdimensions of childhood ADHD, that is, impulsivity, inattention, or hyperactivity was more prominent in this association.

METHODS

In a nation-wide cohort (N = 13,330), we utilized parent reported symptoms of childhood ADHD and clinically ascertained adult BPD diagnoses. The summed total scores of ADHD symptoms and its three subdimensions were used and standardized for effect size comparison. Associations were analyzed using Cox regression with sex and birth-year adjustments. Secondary outcomes were BPD-associated traits (i.e., self-harm and substance use) analyzed using logistic- and linear regression respectively.

RESULTS

ADHD symptom severity was positively associated with BPD with a hazard ratio (HR) of 1.47 (95% confidence interval [CI]: 1.22-1.79) per standard deviation increase in total ADHD symptoms. Impulsivity was the most prominent subdimension with the only statistically significant association when analyzed in a model mutually adjusted for all ADHD subdimensions-HR for inattention: 1.15 (95% CI: 0.85-1.55), hyperactivity: 0.94 (95% CI: 0.69-1.26), impulsivity: 1.46 (95% CI: 1.12-1.91). In secondary analyses, weak positive associations were seen between total ADHD symptom score and self-harm and substance use. In analyses by subdimensions of ADHD, associations were weak and most prominent for inattention in the model with self-harm.

CONCLUSION

Childhood ADHD symptoms were associated with subsequent development of BPD diagnosis and appeared to be driven primarily by impulsivity. Our findings are important for understanding the association between childhood symptoms of ADHD and subsequent BPD.

Sex-different interrelationships of rs945270, cerebral gray matter volumes, and attention deficit hyperactivity disorder: a region-wide study across brain

Previous genome-wide association studies (GWAS) reported that the allele C of rs945270 of the kinectin 1 gene (KTN1) most significantly increased the gray matter volume (GMV) of the putamen and modestly regulated the risk for attention deficit hyperactivity disorder (ADHD). On the other hand, ADHD is known to be associated with a reduction in subcortical and cortical GMVs. Here, we examined the interrelationships of the GMVs, rs945270 alleles, and ADHD symptom scores in the same cohort of children. With data of rs945270 genotypes, GMVs of 118 brain regions, and ADHD symptom scores of 3372 boys and 3129 girls of the Adolescent Brain Cognition Development project, we employed linear regression analyses to examine the pairwise correlations adjusted for the third of the three traits and other relevant covariates, and examine their mediation effects. We found that the major allele C of rs945270 modestly increased risk for ADHD in males only when controlling for the confounding effects of the GMV of any one of the 118 cerebral regions (0.026 ≤ p ≤ 0.059: Top two: left and right putamen). This allele also significantly increased putamen GMV in males alone (left p = 2.8 × 10-5, and right p = 9.4 × 10-5; α = 2.1 × 10-4) and modestly increased other subcortical and cortical GMVs in both sexes (α < p < 0.05), whether or not adjusted for ADHD symptom scores. Both subcortical and cortical GMVs were significantly or suggestively reduced in ADHD when adjusted for rs945270 alleles, each more significantly in females (3.6 × 10-7 ≤ p < α; Top two: left pallidum and putamen) and males (3.5 × 10-6 ≤ p < α), respectively. Finally, the left and right putamen GMVs reduced 14.0% and 11.7% of the risk effects of allele C on ADHD, and allele C strengthened 4.5% (left) and 12.2% (right) of the protective effects of putamen GMVs on ADHD risk, respectively. We concluded that the rs945270-GMVs-ADHD relationships were sex-different. In males, the major allele C of rs945270 increased risk for ADHD, which was compromised by putamen GMVs; this allele also but only significantly increased putamen GMVs that then significantly protected against ADHD risk. In females, the top two GMVs significantly decreasing ADHD risk were left pallidum and putamen GMVs. Basal ganglia the left putamen in particular play the most critical role in the pathogenesis of ADHD.

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.

Adverse childhood experiences predict neurite density differences in young children with and without attention deficit hyperactivity disorder

Adverse childhood experiences (ACEs) put millions of children at risk for later health problems. As childhood represents a critical developmental period, it is important to understand how ACEs impact brain development in young children. In addition, children with attention-deficit/hyperactivity disorder (ADHD) are more likely than typically developing (TD) peers to experience ACEs. Therefore, the current study examined the impact of ACEs on early brain development, using a cumulative risk approach, in a large sample of children with and without ADHD. We examined 198 young children (M_age  = 5.45, 82.3% Hispanic/Latino; 52.5% ADHD) across measures of brain volume, cortical thickness, neurite density index (NDI), and orientation dispersion index (ODI). For the NDI measure, there was a significant interaction between group and cumulative risk (ß = .18, p = .048), such that for children with ADHD, but not TD children, greater cumulate risk was associated with increased NDI in corpus callosum. No other interactions were detected. Additionally, when examining across groups, greater cumulative risk was associated with reduced ODI and volume in the cerebellum, although these findings did not survive a correction for multiple comparisons. Our results highlight the role early cumulative ACEs play in brain development across TD and children with ADHD.

Co-Occurrence of Neurodevelopmental Disorders in Pediatric Sickle Cell Disease

OBJECTIVE

The objective of this study is to retrospectively determine the co-occurrence, associated characteristics, and risk factors for neurodevelopmental disorders (NDD) in a pediatric sickle cell disease (SCD) clinic population.

METHOD

We investigated the co-occurrence and features of NDD in pediatric SCD through a retrospective cohort study conducted between July 2017 and January 2019. The participants were patients with SCD younger than 18 years of age identified from our institutions' clinic rosters and medical records databases.

RESULTS

A total of 276 participants were eligible for study inclusion, and 65 participants were found to have various NDD. Children with SCD and NDD were more likely to have a history of multiple SCD-related complications in comparison to children with SCD without NDD. Children with SCD and NDD were more likely to use disease-modifying therapies in comparison to children with SCD without NDD (χ2 27.2, p < 0.001).

CONCLUSION

Children with SCD and NDD have higher odds of having certain disease-related complications and higher use of disease-modifying treatments than children with SCD who do not have NDD. Screening and diagnoses of NDD may be relevant to clinical management of pediatric SCD.

Atypical sulcal pattern in boys with attention-deficit/hyperactivity disorder

Neurodevelopmental disorders, such as attention‐deficit/hyperactivity disorder (ADHD), are often accompanied by disrupted cortical folding. We applied a quantitative sulcal pattern analysis technique using graph structures to study the atypical cortical folding at the lobar level in ADHD brains in this study. A total of 183 ADHD patients and 167 typical developmental controls matched according to age and gender were enrolled. We first constructed sulcal graphs at the brain lobar level and then investigated their similarity to the typical sulcal patterns. The within‐group variability and interhemispheric similarity in sulcal patterns were also compared between the ADHD and TDC groups. The results showed that, compared with controls, the left frontal, right parietal, and temporal lobes displayed altered similarities to the typical sulcal patterns in patients with ADHD. Moreover, the sulcal patterns in ADHD seem to be more heterogeneous than those in controls. The results also identified the disruption of the typical asymmetric sulcal patterns in the frontal lobe between the ADHD and control groups. Taken together, our results revealed the atypical sulcal pattern in boys with ADHD and provide new insights into the neuroanatomical mechanisms of ADHD.

Is there any incremental benefit to conducting neuroimaging and neurocognitive assessments in the diagnosis of ADHD in young children? A machine learning investigation

Given the negative trajectories of early behavior problems associated with ADHD, early diagnosis is considered critical to enable intervention and treatment. To this end, the current investigation employed machine learning to evaluate the relative predictive value of parent/teacher ratings, behavioral and neural measures of executive function (EF) in predicting ADHD in a sample consisting of 162 young children (ages 4–7, mean age 5.55, 82.6 % Hispanic/Latino). Among the target measures, teacher ratings of EF were the most predictive of ADHD. While a more extensive evaluation of neural measures, such as diffusion-weighted imaging, may provide more information as they relate to the underlying cognitive deficits associated with ADHD, the current study indicates that measures of cortical anatomy obtained in research studies, as well cognitive measures of EF often obtained in routine assessments, have little incremental value in differentiating typically developing children from those diagnosed with ADHD. It is important to note that the overlap between some of the EF questions in the BRIEF, and the ADHD symptoms could be enhancing this effect. Thus, future research evaluating the importance of such measures in predicting children’s functional impairment in academic and social areas would provide additional insight into their contributing role in ADHD.

Gray matter networks associated with attention and working memory deficit in ADHD across adolescence and adulthood

Attention-deficit/hyperactivity disorder (ADHD) is a childhood-onset neuropsychiatric disorder and may persist into adulthood. Working memory and attention deficits have been reported to persist from childhood to adulthood. How neuronal underpinnings of deficits differ across adolescence and adulthood is not clear. In this study, we investigated gray matter of two cohorts, 486 adults and 508 adolescents, each including participants from ADHD and healthy controls families. Two cohorts both presented significant attention and working memory deficits in individuals with ADHD. Independent component analysis was applied to the gray matter of each cohort, separately, to extract cohort-inherent networks. Then, we identified gray matter networks associated with inattention or working memory in each cohort, and projected them onto the other cohort for comparison. Two components in the inferior, middle/superior frontal regions identified in adults and one component in the insula and inferior frontal region identified in adolescents were significantly associated with working memory in both cohorts. One component in bilateral cerebellar tonsil and culmen identified in adults and one component in left cerebellar region identified in adolescents were significantly associated with inattention in both cohorts. All these components presented a significant or nominal level of gray matter reduction for ADHD participants in adolescents, but only one showed nominal reduction in adults. Our findings suggest although the gray matter reduction of these regions may not be indicative of persistency of ADHD, their persistent associations with inattention or working memory indicate an important role of these regions in the mechanism of persistence or remission of the disorder.

Digital health interventions (DHI) for the treatment of attention deficit hyperactivity disorder (ADHD) in children - a comparative review of literature among various treatment and DHI

The objective of this study is to compare game-based digital therapeutic device and other DHI like (smartphone apps, wearable technologies) for ADHD with the current pharmacological and behavior therapy. The FDA has approved a game-based digital therapeutic device - EndeavorRx, for the treatment of ADHD in pediatric patients belonging to the age group of 8-12 years old. This has been primarily recommended for the treatment of inattentive or combined-type ADHD who have demonstrated an attention issue. This is the first game-based therapeutic device to be approved by the FDA for any type of condition. According to the FDA, this has been shown to improve attention which is measured by computer-based testing. Objective: The objective of this study is to compare a game-based digital therapeutic device and other DHI (smartphone apps, wearable technologies) with the current pharmacological and behavior therapy used in the treatment of ADHD.

Rates of Performance Validity Test Failure for ADHD Evaluations in a Military Population: An Exploratory Study

Objective: Investigate rates of Performance Validity Test (PVT) failures in a group of active duty (AD) military participants referred for ADHD evaluations and other characteristics of those referred for evaluation. Method: AD service members referred for ADHD evaluations were given PVTs as part of assessment. PVT pass/fail groups were compared on age, estimated premorbid intelligence, history of ADHD, other mental health problems, and functional impairment. Results: PVT failure rate was consistent with other studies. Fail group was younger and lower estimated premorbid intelligence than those that passed. Groups based on other variables did not significantly differ. Failure group also performed worse on a measure of attention. Many individuals were referred with no childhood history of ADHD or objective evidence of impaired function. Conclusion: Rates of PVT failures were similar to those found in civilian university and veteran military settings. Screening candidates for specific Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria for ADHD was only minimally followed.

Does ADHD worsen inhibitory control in preschool children born very premature and/or with very low birth weight?

INTRODUCTION

Deficits in executive functioning, especially in inhibitory control, are present in children born very premature and/or with very low birth weight (VP/VLBW) and in children with attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To evaluate whether ADHD imposes additional inhibitory control (IC) deficits in preschoolers born VP/VLBW.

METHODS

79 VP/VLBW (4 to 7 years) children were assessed for ADHD using the Schedule for Affective Disorders and Schizophrenia for School Aged Children - Present and Lifetime Version (K-SADS-PL). IC was measured with Conners' Kiddie Continuous Performance Test (K-CPT 2) and the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P).Results: No significant differences were found between ADHD (n = 24) and non-ADHD children (n = 55) for any of the measures (p = 0.062 to p = 0.903). Both groups had deficits in most K-CPT 2 scores compared to normative samples, indicating poor IC and inconsistent reaction times.

CONCLUSIONS

ADHD does not aggravate IC deficits in VP/VLBW children. Either neuropsychological tasks and parent reports of executive functions (EFs) may not be sensitive enough to differentiate VP/VLBW preschoolers with and without ADHD, or these children's EFs are already so impaired that there is not much room for additional impairments imposed by ADHD.

Design Fluency in Children with ADHD and Comorbid Disorders

BACKGROUND

Attention deficit/hyperactivity disorder (ADHD) is often associated with frontal executive impairment in children. Oppositional defiant disorder (ODD) and anxiety disorders (AD) frequently accompany ADHD, but the impact of these comorbid disorders on cognition remains elusive. The five-point test (FPT), a design fluency task, has been shown to be sensitive to neurological damage, specifically to frontal lobe lesions in patients with brain injuries. The purpose of this study was to compare the performances of neurotypical children with that of children with ADHD, ADHD-ODD, and ADHD-AD on the FPT in order to examine whether these groups could be distinguished from one another based on their cognitive profile.

METHODS

A total of 111 children aged 8 to 11 years old participated in the study. Six measures from the FPT were used to characterize their performance.

RESULTS

Statistically significant differences between groups were observed for five of the six FPT measures. Essentially, children with ADHD-ODD made more repeated designs than the three other groups (control p > 0.001, ADHD p = 0.008, ADHD-AD p = 0.008), while children with ADHD-AD produced fewer total and correct designs than the control and ADHD groups (p = 0.009).

CONCLUSIONS

This suggests that comorbidities have an additive impact on the cognitive profile of children with ADHD. Design fluency may be a sensitive measure for capturing the subtle cognitive deficits that are likely to be involved in these disorders.

Diagnosis and Treatment Options for Preschoolers with Attention-Deficit/Hyperactivity Disorder

Objective: The Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), classifies attention-deficit/hyperactivity disorder (ADHD) as a neurodevelopmental disorder, with symptoms becoming apparent as early as the preschool years. Early recognition can lead to interventions such as parent/teacher-administered behavior therapy, the recommended first-line treatment for preschool patients. There are few data, however, to inform the use of second-line, pharmacotherapy options in this population. In this review, we identified recent literature on the diagnosis and treatment of ADHD in preschool children. Methods: A PubMed and clinicaltrials.gov search was conducted for trials assessing efficacy or safety of ADHD medications in children aged <6 years. Diagnostic methods and criteria focusing on recognition of ADHD in preschool children were also surveyed. Results: The DSM-5 describes different manifestations of ADHD in preschool versus school-aged children, but does not list separate criteria by age group. Importantly, behaviors indicative of ADHD in older children may be developmentally appropriate in preschool children. Several behavioral rating scales have been validated in children younger than 6 years of age for assessing ADHD. The Preschool ADHD Treatment Study (PATS) has provided the most extensive efficacy and safety data on methylphenidate (MPH) for ADHD in preschoolers to date, with significant improvement in ADHD symptoms observed with MPH compared with placebo, although adverse event-related discontinuation was higher in PATS compared with studies of MPH for ADHD in school-aged children. Since PATS was conducted, few studies designed to assess ADHD medication effectiveness in preschool children have been published. One article reported significant improvement in ADHD symptoms with MPH (immediate release) versus placebo, two studies showed no difference between MPH and risperidone or MPH plus risperidone in relief of ADHD symptoms, and one study demonstrated the efficacy of atomoxetine versus placebo for ADHD symptoms in preschoolers. Conclusions: Further research is needed on pharmacotherapy for preschool children with ADHD.

Gait control in children with attention-deficit/hyperactivity disorder

The current profile of gait control in children with ADHD is incomplete and predominately based on children walking forward at a self-selected pace. There are no studies of potential gait deficits in this clinical population when walking in different directions in combination with varying rates of stepping that are freely selected and entrained to an external stimulus. The purpose of the current study was to address this lack of information by assessing gait of children aged 7-17 years with (n = 17) and without (n = 26) ADHD. Participants walked forward and backward along an electronically instrumented carpet at a self-selected stepping rate and in synchrony to a metronome that dictated an increased and decreased stepping rate. Using repeated measures analysis of covariance (ANCOVA) to assess spatiotemporal gait parameters, results showed that children with ADHD exhibited a significantly exaggerated, toes 'turned out,' foot position for all walking conditions compared to typically developing children. When walking backward, children with ADHD produced an increased step width, higher stepping cadence, and increased velocity. Additionally, coefficient of variation ratios indicated that children with ADHD produced greater variability of velocity, cadence, and step time for all walking conditions, and greater variability for stride length when walking at an increased stepping rate. Results were interpreted in terms of clinical significance and practical ramifications that inform rehabilitation specialists in designing therapies that ameliorate the reported gait deficits.

Synaptic development of layer V pyramidal neurons in the prenatal human prefrontal neocortex: a Neurolucida-aided Golgi study

The prefrontal neocortex is involved in many high cognitive functions in humans. Deficits in neuronal and neurocircuitry development in this part of the cerebrum have been associated with various neuropsychiatric disorders in adolescents and adults. There are currently little available data regarding prenatal dendrite and spine formation on projecting neurons in the human prefrontal neocortex. Previous studies have demonstrated that Golgi silver staining can identify neurons in the frontal lobe and visual cortex in human embryos. In the present study, five fetal brains, at 19, 20, 26, 35, and 38 gestational weeks, were obtained via the body donation program at Xiangya School of Medicine, Central South University, China. Golgi-stained pyramidal neurons in layer V of Brodmann area 46 in fetuses were quantitatively analyzed using the Neurolucida morphometry system. Results revealed that somal size, total dendritic length, and branching points of these neurons increased from 26 to 38 gestational weeks. There was also a large increase in dendritic spines from 35 to 38 gestational weeks. These findings indicate that, in the human prefrontal neocortex, dendritic growth in layer V pyramidal neurons occurs rapidly during the third trimester of gestation. The use of human fetal brain tissue was approved by the Animal Ethics Committee of Xiangya School of Medicine, Central South University, China (approval No. 2011-045) on April 5, 2011.