Resting state dynamic functional connectivity in children with attention deficit/hyperactivity disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity.
• Understanding the neural underpinnings of ADHD is crucial for developing effective interventions.
• Previous research has explored static functional connectivity, but dynamic changes remain less understood.

Purpose of the Study:

• To investigate group differences in dynamic functional connectivity (dFC) using resting-state fMRI data in children with inattentive (ADHD_I) and combined (ADHD_C) ADHD compared to typically developing (TD) children.
• To identify distinct functional connectivity states and analyze transition probabilities between them in ADHD subtypes and TD controls.
• To explore state-dependent alterations in intra- and inter-network connectivity within and between large-scale resting-state networks (RSNs).

Main Methods:

• Utilized resting-state functional MRI data from 113 children with ADHD (46 ADHD_I, 67 ADHD_C) and 76 TD children.
• Applied independent component analysis (ICA) to decompose data into RSNs, followed by k-means clustering to identify three discrete functional connectivity (FC) states.
• Employed a hidden Markov model to estimate transition probabilities between states and analyzed state-dependent connectivity alterations.

Main Results:

• Both ADHD_I and ADHD_C groups exhibited state-dependent alterations in intra- and inter-network connectivity compared to TD controls.
• Children with ADHD spent less time in state 1, showing weaker intra-hemispheric connectivity, with ADHD_I also displaying weaker inter-hemispheric connectivity.
• ADHD groups spent more time in state 2, characterized by abnormal corticosubcortical and corticocerebellar connectivity; ADHD_C showed distinct temporal region connectivity in state 3.

Conclusions:

• Distributed abnormalities in static (sFC) and dynamic functional connectivity (dFC) were observed across cortical and subcortical regions in both ADHD subtypes.
• Dynamic changes in brain functional connectivity offer a more comprehensive explanation for ADHD pathophysiology, including deficits in visual cognition, attention, memory, emotion processing, and motor control.
• Findings highlight the importance of considering dynamic brain connectivity patterns for a deeper understanding of ADHD.