A Parietal Biomarker for ADHD Liability: As Predicted by the Distributed Effects Perspective Model of ADHD

Abstract

BackgroundWe previously hypothesized that poor task-directed sensory information processing should be indexed by increased weighting of right hemisphere (RH) biased attention and visuo-perceptual brain functions during task operations and have demonstrated this phenotype in ADHD across multiple studies, using multiple methodologies. However, in our recent distributed effects model of ADHD, we surmised that this phenotype is not ADHD specific, but rather more broadly reflective of any circumstance that disrupts the induction and maintenance of an emergent task-directed neural architecture. Under this view, increased weighting of RH-biased attention and visuo-perceptual brain functions is expected to generally index neurocognitive sets that are not optimized for task-directed thought and action, and when durable expressed, liability for ADHD.MethodThe current study tested this view by examining whether previously identified rightward parietal EEG asymmetry in ADHD was associated with common ADHD characteristics and comorbidities [i.e., ADHD risk factors (RFs)].ResultsBarring one exception (non-right handedness), we found that it was. Rightward parietal asymmetry (RPA) was associated with carrying the DRD4-7R risk allele, being male, having mood disorder, and having anxiety disorder. However, differences in the specific expression of RPA were observed, which are discussed in relation to possible unique mechanisms underlying ADHD liability in different ADHD RFs.ConclusionRightward parietal asymmetry appears to be a durable feature of ADHD liability, as predicted by the Distributed Effects Perspective Model of ADHD. Moreover, variability in the expression of this phenotype may shed light on different sources of ADHD liability.

Inter-hemispherical asymmetry in default-mode functional connectivity and BAIAP2 gene are associated with anger expression in ADHD adults

“…Moreover, an abnormal hemispheric asymmetry of brain structure and function was also consistently reported in ADHD (Dennis and Thompson, 2013;Shang et al, 2013;Cao et al, 2014;Hale et al, 2014Hale et al, , 2015Keune et al, 2015;Silk et al, 2015), suggesting a possible neurodevelopmental scenario for this disorder.…”

“…Based on previous reports of abnormal laterality of the ADHD brain (Dennis and Thompson, 2013;Shang et al, 2013;Cao et al, 2014;Hale et al, 2014Hale et al, , 2015Keune et al, 2015;Silk et al, 2015), we could postulate that the asymmetric expression of neurodevelopmental genes might be at the origin of structural and functional changes in this disorder. However, these changes are not clear yet, as both a dysfunctional activity of the right hemisphere (Vance et al, 2007;Smith et al, 2008;Chamberlain et al, 2009;Bush, 2011) and the opposite (Cao et al, 2014;Hale et al, 2014Hale et al, , 2015 have been reported in literature. Moreover, the reflections of these unilateral activation deficits on functional connectivity are not trivial and require dedicated analyses focused on network properties (Dennis and Thompson, 2013;Cao et al, 2014).…”

Hemispheric brain asymmetry differences in youths with attention-deficit/hyperactivity disorder

“…In ADHD, early lesion studies suggested a role for unilateral right hemisphere dysfunction ( Heilman and Van Den Abell, 1980 ; Stefanatos and Wasserstein, 2001 ). Previous studies have investigated aspects of structural brain symmetry in ADHD ( Rubia et al, 2000 ; Hale et al, 2015 ; Shaw et al, 2009a ). One of these studies reported increased asymmetry in the TD group, using homologous points on the cortex for comparison ( Shaw et al, 2009a ).…”

Electroencephalographic and Neuroimaging Asymmetry Correlation in Patients with Attention-Deficit Hyperactivity Disorder

“…Other authors have suggested that the DMN is not altered at rest but in the transition from rest to task [ 15 ]. Abnormalities in the DMN are also evident in structural-functional right-based DMN asymmetry [ 10 , 16 ]. Increased or atypical functional asymmetry and abnormal interhemispheric processing in ADHD have also been reported by Fassbender and Schweitzer [ 17 ].…”