Structural and functional connectivity in children and adolescents with and without attention deficit/hyperactivity disorder

Abstract

Background: Attention deficit/hyperactivity disorder (ADHD) has frequently been associated with changes in resting-state functional connectivity, and decreased white matter (WM) integrity. In the current study, we investigated functional connectivity within Default Mode and frontal control resting-state networks (RSNs) in children with and without ADHD. We hypothesized the RSNs of interest would show a pattern of impaired functional integration and segregation and corresponding changes in WM structure. Methods: Resting-state fMRI and diffusion-weighted imaging data were acquired from 35 participants with ADHD and 36 matched typically developing peers, aged 6 through 18 years. Functional connectivity was assessed using independent component analysis. Network topology and WM connectivity were further investigated using graph theoretical measures and tract-based spatial statistics (TBSS). Results: Resting-state fMRI analyses showed increased functional connectivity in right inferior frontal gyrus (IFG), and bilateral medial prefrontal cortex (mPFC) within the Default Mode and frontal control networks. Furthermore, a more diffuse spatial pattern of functional connectivity was found in children with ADHD. We found no group differences in structural connectivity as assessed with TBSS or graph theoretical measures. Conclusions: Resting-state networks show a more diffuse pattern of connectivity in children with ADHD. The increases in functional connectivity in right IFG and bilateral mPFC in children with ADHD may reflect reduced or delayed functional segregation of prefrontal brain regions. As these functional changes were not accompanied by changes in WM, they may precede the development of the frequently reported changes in WM structure.

Topological Data Analysis reveals robust alterations in the whole-brain and frontal lobe functional connectomes in Attention-Deficit/Hyperactivity Disorder

“…In addition, our results showed a similarly widespread pattern in several functional sub-networks, mainly the default mode, but also attention, salience, fronto-parietal and auditory nodes, among others ( Figure 5). Although the latter results did not survive FDR correction, they provide the basis to infer the potential functional systems being affected in ADHD, being consistent with the current theories involving such networks (Castellanos and Aoki, 2016), particularly with the DMN interference hypothesis, which is based on the findings of altered interactions between the DMN and networks involved in top-down executive control (Fox et al, 2005(Fox et al, , 2007Kelly et al, 2008;Castellanos and Aoki, 2016;Elton et al, 2014;Hoekzema et al, 2014;Bos et al, 2017;Qian et al, 2019).…”

Shared and distinct resting functional connectivity in children and adults with attention-deficit/hyperactivity disorder

“…Extant imaging studies have reported brain structural and functional differences between patients with ADHD and HCs, both in childhood and adulthood. Many functional magnetic resonance imaging (fMRI) findings heavily support that ADHD involves a distributed pattern of brain alterations 3,4 . According to Rubia et al, functional abnormalities in fronto-cortical and fronto-subcortical networks are core deficits in both children and adults with ADHD 5 .…”

Differences in brain networks of children with ADHD: Whole‐brain analysis of resting‐state fMRI

“…Increased FC was reported in the right inferior frontal gyrus and bilateral prefrontal cortex within the default mode and frontal control networks in participants with ADHD . It was reported that 8.3% smaller total cerebellar volume was observed in boys with ADHD, furthermore a significant decrease was noted only in the frontal lobes in terms of lobar volume .…”

“…Increased FC was reported in the right inferior frontal gyrus and bilateral prefrontal cortex within the default mode and frontal control networks in participants with ADHD. 41 It was reported that 8.3% smaller total cerebellar volume was observed in boys with ADHD, furthermore a significant decrease was noted only in the frontal lobes in terms of lobar volume. 42 In our study, compared with the control group according to IC26 which was identified frontal network, FC in ADHD have not changed in the left areas and decreased in the right areas in the frontal network when considering volume in total.…”