Abstract
BackgroundThe authors sought to map gray matter changes in Attention Deficit Hyperactivity Disorder (ADHD) using a novel technique incorporating neuro-imaging and genetic meta-analysis methods.MethodsA systematic search was conducted for voxel-based structural magnetic resonance imaging studies of patients with ADHD (or with related disorders) in relation to comparison groups. The authors carried out meta-analyses of the co-ordinates of gray matter differences. For the meta-analyses they hybridised the standard method of Activation Likelihood Estimation (ALE) with the rank approach used in Genome Scan Meta-Analysis (GSMA). This system detects three-dimensional conjunctions of co-ordinates from multiple studies and permits the weighting of studies in relation to sample size.ResultsFor gray matter decreases, there were 7 studies including a total of 114 patients with ADHD (or related disorders) and 143 comparison subjects. Meta-analysis of these studies identified a significant regional gray matter reduction in ADHD in the right putamen/globus pallidus region. Four studies reported gray matter increases in ADHD but no regional increase was identified by meta-analysis.ConclusionIn ADHD there is gray matter reduction in the right putamen/globus pallidus region. This may be an anatomical marker for dysfunction in frontostriatal circuits mediating cognitive control. Right putamen lesions have been specifically associated with ADHD symptoms after closed head injuries in children.
Highlights
The authors sought to map gray matter changes in Attention Deficit Hyperactivity Disorder (ADHD) using a novel technique incorporating neuro-imaging and genetic meta-analysis methods
Study Ascertainment Studies were considered for inclusion if they were published before February 2008 as an article, if they compared a group of subjects with ADHD and a comparison group, if they utilized voxel-based morphometry analysis of Magnetic Resonance Images (MRI) datasets to investigate differences in whole-brain structure, and if they reported the three-dimensional co-ordinates of brain changes in stereotactic space
This study demonstrates the application of a novel meta-analysis technique incorporating elements of Activation Likelihood Estimation and Genome Scan Meta-Analysis
Summary
The authors sought to map gray matter changes in Attention Deficit Hyperactivity Disorder (ADHD) using a novel technique incorporating neuro-imaging and genetic meta-analysis methods. The core symptoms of Attention Deficit Hyperactivity Disorder (ADHD) are inattention, impulsivity and hyperactivity [1]. Low striatal dopamine levels contribute to impairments in reinforcement learning and working memory, while cortical noradrenergic deficits may contribute to other cognitive deficits [4]. In support of this model, a meta-analysis of functional imaging studies of ADHD (fMRI and PET) found that the most consistent abnormalities in patients included deficits in neural activity in frontostriatal circuits [3]
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