Jesse Bledsoe

A Magnetic Resonance Imaging Study of the Cerebellar Vermis in Chronically Treated and Treatment-Naïve Children with Attention-Deficit/Hyperactivity Disorder Combined Type

BACKGROUND Because of its dense connections to the prefrontal cortex and basal ganglia, the cerebellum is thought to play an important role in cognition. Numerous magnetic resonance imaging (MRI) studies have found abnormalities in the cerebellum in children with attention-deficit/hyperactivity disorder (ADHD). While some studies in animal and human models suggest that certain brain structures are affected by chronic stimulant medication, it is unclear whether the cerebellum is also affected. The purpose of the current study was to determine if cerebellar morphology was different in treatment-naïve versus chronically treated children with ADHD. METHODS There were 32 boys and 15 girls total (N = 47) that comprised three groups: ADHD-combined type (ADHD-C) children with no history of stimulant medication treatment (n = 14), ADHD-C children chronically treated with stimulant medication (n = 18), and typically developing control children (n = 15). RESULTS Treatment-naïve children with ADHD had significantly smaller area in the posterior inferior vermis (lobules VIII-X) than both chronically treated children with ADHD (p = .004) and typically developing control children (p = .001). No differences were observed between chronically treated children with ADHD and control children. CONCLUSIONS The results from this study suggest that chronic stimulant treatment may normalize the development of important areas of the cerebellar vermis in children with ADHD.

Neuroanatomical and Neuropsychological Correlates of the Cerebellum in Children With Attention-Deficit/Hyperactivity Disorder-Combined Type

OBJECTIVE Studies of healthy individuals and those with cerebellar damage have implicated the cerebellum in a variety of cognitive and behavioral processes. Decreased cerebellar volume has been found in children with attention-deficit/hyperactivity disorder (ADHD) and differentially related to behavioral outcomes. The present study investigated whether smaller cerebellar vermis volume was present in children with ADHD-combined type (ADHD-C) compared with controls and whether volume related to parent- and teacher-reported levels of ADHD symptomatology. METHOD T1-weighted magnetic resonance images and parent- and teacher-reported ADHD symptoms were acquired for 32 children diagnosed with ADHD-C and 15 typically developing controls. Participants were right-handed, had no comorbid diagnoses of learning disabilities, conduct disorder, or affective/mood disorder, and were 9 to 15 years of age. RESULTS Participants with ADHD-C showed significantly smaller volume in the posterior inferior vermis compared with controls. No statistically significant differences were observed for cerebral volume, anterior vermis volume, posterior superior volume, or total cerebellar volume. Regression analyses indicated that a significant amount of the variance in parent-reported Behavior Assessment System for Children, Second Edition, Hyperactivity and Attention and Conners Restless/Impulsive ratings was explained by volume of the posterior inferior vermis. CONCLUSIONS Consistent with previous studies, children with ADHD had smaller volume in the posterior inferior vermis. New findings emerged with smaller volume of the posterior inferior vermis predicting a significant amount of the variance in parent-reported hyperactivity, attention, and restlessness/impulsivity. Thus, symptoms of hyperactivity and inattention in ADHD may be partly explained by smaller volume of the cerebellar vermis and its connections within the cerebrum.

Anterior cingulate cortex and symptom severity in attention-deficit/hyperactivity disorder.

The cause of attention-deficit/hyperactivity disorder (ADHD) has been linked to abnormalities in prefrontal-striatal-cerebellar networks, but the brain-behavioral correlates are relatively equivocal. Children with ADHD and healthy controls underwent MRI and neuropsychological testing. Brain cortical thickness was analyzed for the bilateral rostral and caudal anterior cingulate cortex (ACC). Inhibitory control was assessed with the Stroop Inhibition test, and ADHD symptom severity was assessed with parent and teacher behavioral questionnaires. Brain-behavior relationships were calculated between cortical thickness and behavioral measures with regression models. Children with ADHD had significant cortical thinning in the right rostral ACC but nonsignificant thinning in right caudal, left caudal, or left rostral ACC compared with healthy control children after statistical correction for multiple comparisons. Further, right rostral ACC thickness predicted a significant amount of the variance in parent- and teacher-reported symptoms of ADHD. Exploratory analysis showed that cortical thickness was not related to psychostimulant medication history. Symptoms of ADHD may be related to reductions in cortical thickness in the right anterior attention network, a region implicated in behavioral error detection, impulsivity, and inhibitory control.

A critical review of the literature on NLD as a developmental disorder

The extant research on nonverbal learning disability (NLD) was analyzed in this review. Studies were defined for use in the review as those that appeared in a peer-reviewed journal and included participants characterized as having NLD. Each study also needed to provide a statistical analysis of dependent variables. An a priori system was used to evaluate the quality of the research. Of the 88 publications found, 32 met criteria for inclusion in the review, with 6 meeting full criteria as strong studies. The diagnostic criteria used and the research findings are briefly discussed, as are proposed guidelines for future research.

Volumetric MRI Differences in Treatment Naïve and Chronically Treated Adolescents With ADHD-Combined Type

Objective: The purpose of this study was to determine whether there are differences in the volume of specific brain regions using magnetic resonance imaging (MRI) between children and adolescents with ADHD and controls and whether such differences are related to the participants’ history of stimulant treatment. Method: A total of 16 healthy controls, 16 children, and adolescents with ADHD-combined (ADHD-C) type with a history of stimulant treatment, and 13 children and adolescents with ADHD-C type treatment naïve participated. Results: Total frontal, prefrontal, and caudate volumes were larger for children and adolescents with ADHD compared with controls with no differences based on medication history with larger right gray and white matter prefrontal volumes in the ADHD groups. A medication difference was found with the right anterior cingulate cortex smaller in children and adolescents without a treatment history. Conclusion: These findings suggest that aberrant prefrontal and caudate volumes in ADHD-C may compromise functioning of the frontostriatal circuitry.

Gender differences in brain activation on a mental rotation task.

ABSTRACT Few neuroimaging studies have explored gender differences on mental rotation tasks. Most studies have utilized samples with both genders, samples mainly consisting of men, or samples with six or fewer females. Graduate students in science fields or liberal arts programs (20 males, 20 females) completed a mental rotation task during functional magnetic resonance imaging (fMRI). When a pair of cube figures was shown, the participant made a keypad response based on whether the pair is the same/similar or different. Regardless of gender, the bilateral middle frontal gyrus, bilateral intraparietal sulcus (IPS), and the left precuneus were activated when a subject tried to solve the mental rotation task. Increased activation in the right inferior frontal gyrus/middle frontal gyrus, the left precuneus/posterior cingulate cortex/cuneus region, and the left middle occipital gyrus was found for men as compared to women. Better accuracy and shorter response times were correlated with an increased activation in the bilateral intraparietal sulcus. No significant brain activity differences related to mental rotation were found between academic majors. These findings suggest that networks involved in visual attention appear to be more strongly activated in the mental rotation tasks in men as compared to women. It also suggests that men use a more automatic process when analyzing complex visual reasoning tasks while women use a more top-down process.

Response Inhibition and Academic Abilities in Typically Developing Children with Attention-Deficit-Hyperactivity Disorder-Combined Subtype

Research in Attention-Deficit/Hyperactivity Disorder (ADHD) generally utilizes clinical samples or children with comorbid psychiatric diagnoses. Findings indicated that children with ADHD experience academic underachievement and poor performance on measures of response inhibition (RI). Less is known, about the neuropsychological profile of typically developing children with ADHD. The aim of the current study was twofold: (1) determine if academic skills and RI were impaired in typically developing children with ADHD-combined subtype (ADHD-C) and (2) determine to what extent RI may predict academic abilities. Children with ADHD-C did not differ on any academic domain from controls. Children with ADHD-C performed more poorly than controls on RI measures. Regression analyses suggest that Written Expression ability was significantly influenced by RI. No other academic domain was related to RI. Results suggest that children with ADHD-C may experience impairments in RI despite adequate academic functioning. Impaired RI is not solely responsible for difficulties found in academic skills in ADHD-C.

Updates on Attention-Deficit/Hyperactivity Disorder and Learning Disorders

The relationship of attention-deficit/hyperactivity disorder (ADHD) to learning disorders was reviewed and included reading disability, mathematics learning disability, and nonverbal learning disability. Genetic, neuroimaging, and neuropsychological functioning were examined for each disorder, along with a discussion of any existing literature when ADHD co-occurred with the disorder. All the disorders were found to frequently co-occur with ADHD. A review of the underlying neuroanatomic and neurofunctional data found specific structures that frequently co-occur in these disorders with others that are specific to the individual diagnosis. Aberrations in structure and/or function were found for the caudate, corpus callosum, and cerebellum, making these structures sensitive for the disorder but not specific. Suggestions for future research, particularly in relation to intervention, are provided.

Unique white matter microstructural patterns in ADHD presentations—a diffusion tensor imaging study

Attention‐deficit/hyperactivity disorder predominantly inattentive (ADHD‐PI) and combined (ADHD‐C) presentations are likely distinct disorders that differ neuroanatomically, neurochemically, and neuropsychologically. However, to date, little is known about specific white matter (WM) regions differentiating ADHD presentations. This study examined differences in WM microstructure using diffusion tensor imaging (DTI) data from 20 ADHD‐PI, 18 ADHD‐C, and 27 typically developed children. Voxel‐wise analysis of DTI measurements in major fiber bundles was carried out using tract‐based spatial statistics (TBSS). Clusters showing diffusivity abnormalities were used as regions of interest for regression analysis between fractional anisotropy (FA) and neuropsychological outcomes. Compared to neurotypicals, ADHD‐PI children showed higher FA in the anterior thalamic radiations (ATR), bilateral inferior longitudinal fasciculus (ILF), and in the left corticospinal tract (CST). In contrast, the ADHD‐C group exhibited higher FA in the bilateral cingulum bundle (CB). In the ADHD‐PI group, differences in FA in the left ILF and ATR were accompanied by axial diffusivity (AD) abnormalities. In addition, the ADHD‐PI group exhibited atypical mean diffusivity in the forceps minor (FMi) and left ATR and AD differences in right CB compared to healthy subjects. Direct comparison between ADHD presentations demonstrated radial diffusivity differences in FMi. WM clusters with FA irregularities in ADHD were associated with neurobehavioral performance across groups. In conclusion, differences in WM microstructure in ADHD presentations strengthen the theory that ADHD‐PI and ADHD‐C are two distinct disorders. Regions with WM irregularity seen in both ADHD presentations might serve as predictors of executive and behavioral functioning across groups. Hum Brain Mapp 37:3323–3336, 2016.

Regional Volumetric Differences Based on Structural MRI in Children With Two Subtypes of ADHD and Controls

Objective: The purpose of this study was to compare groups of children with two subtypes of ADHD and controls on selected regions using volumetric magnetic resonance imaging (MRI) measures. Children with ADHD were expected to have smaller volumes of the anterior cingulate cortex (ACC) and caudate. Parent behavioral rating measures of hyperactivity were predicted to relate to the volume of the caudate and attention with the ACC. Method: There were a total of 74 children in the final sample (27 controls, 25 ADHD:Combined type [ADHD:C], 22 ADHD:Inattentive type [ADHD:I]). Results: Findings indicated that the ADHD:C group had bilaterally smaller volumes of the caudate and ACC compared with the other two groups. In addition, parent ratings of attention and hyperactivity significantly predicted the right volume of the ACC, whereas hyperactivity ratings predicted the volume of the right caudate. Analysis of the ADHD groups without the control confirmed these findings. Conclusion: These findings indicate that different structures are related to the ADHD subtypes and suggest that they may be different phenotypes.