Altered structural connectivity is related to attention deficit/hyperactivity subtypes: A DTI study

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Neuroimaging

Background:

• Attention Deficit/Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental disorder.
• Understanding ADHD subtypes is crucial for targeted interventions.
• White matter (WM) microstructural alterations are implicated in ADHD.

Purpose of the Study:

• To investigate novel insights into white matter (WM) microstructural properties of ADHD subtypes.
• To compare WM differences between ADHD-Combined (ADHD-C) and ADHD-Predominantly Inattentive (ADHD-I) subtypes.
• To explore differences between ADHD-C and ADHD-Restricted Inattentive (ADHD-RI) subtypes.

Main Methods:

• Tract-based spatial statistics (TBSS) applied to Diffusion Tensor Imaging (DTI) data.
• Analysis of fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) measures.
• Inclusion of stimulant-naïve children and adolescents (aged 8-15) with homogenous DAT1 gene polymorphism and minimal comorbidity.

Main Results:

• Increased radial diffusivity (RD) in bilateral brain areas and axial diffusivity (AD) in left-sided regions were observed when comparing ADHD-C with ADHD-I.
• Specific affected areas include the corpus callosum, internal capsule, corona radiata, thalamic radiation, and superior longitudinal fasciculus.
• ADHD-C group showed increased AD values compared to the ADHD-RI group in overlapping brain areas.
• No significant diffusivity differences were found between controls and any ADHD group (overall or subgroups).

Conclusions:

• Significant microstructural differences exist among ADHD subtypes, suggesting distinct underlying neuropathology.
• These findings provide preliminary evidence for distinct WM properties in ADHD subtypes.
• Further research is warranted to elucidate the specific neurobiological mechanisms differentiating ADHD subtypes.