SNUH's sudy reveals age-related changes in brain function of children with ADHD

A recent study conducted by a research team at Seoul National University Hospital (SNUH) has revealed that cerebral blood flow (CBF) in children with attention deficit hyperactivity disorder (ADHD) varies significantly with age. 

The findings indicate that changes in brain function in children with ADHD are most pronounced between the ages of seven and eight, suggesting that the onset or intensification of ADHD symptoms may be particularly noticeable during this period. This research is expected to provide crucial data for understanding the developmental characteristics of ADHD and for developing age-specific treatment and intervention strategies.

The study was conducted by Professor Kim Bung-nyun's team from the Department of Child and Adolescent Psychiatry, with clinical fellow Lim You-bin, as well as Professor Sohn Chul-ho’s team from the Department of Radiology, with Research Professor Song Hui-jin from the Biomedical Research Institute at SNUH.

They announced their findings on Wednesday, utilizing arterial spin labeling-magnetic resonance imaging (ASL-MRI) to explore the developmental trajectories of brain activity in children with ADHD and those without.

“This study demonstrates the potential of ASL-MRI to non-invasively diagnose and evaluate changes in brain function in children with ADHD across different ages,” said Professor Sohn. “This is particularly important when researching younger children to observe brain functional changes as they age. We plan to conduct further multidisciplinary research on both structural and functional changes in the brain."

ADHD is one of the most common neurodevelopmental disorders, affecting 5 to 10 percent of preschool and school-age children. It is characterized by symptoms such as distractibility, hyperactivity, impulsiveness, and difficulties with tasks requiring sustained attention.

Although the exact cause of ADHD is not fully understood, it is known to result from a complex interplay of genetic and environmental factors that lead to neurobiological changes. Understanding the changes related to brain development is, therefore, crucial for alleviating ADHD symptoms. 

While previous studies have identified differences in brain volume and structure in children with ADHD, there has been a lack of research into the dynamic changes in brain function associated with age.

Therefore, there is a pressing need for additional research utilizing advanced technologies to delve into how brain function evolves with age, especially given the challenges of brain imaging in younger children. 

The SNUH research team conducted a study involving 157 children with ADHD and 109 children in a control group. For age-matched analyses, the children were categorized into three subgroups by age range: six to seven years, eight to nine years, and 10 to 12 years. 

All participants underwent ASL-MRI, a noninvasive technique for measuring CBF that labels water molecules in the blood to measure regional cerebral blood flow (rCBF) without radiation exposure. This technique is particularly suitable for sensitive groups like children.

Comparative analysis revealed that children with ADHD had significantly lower CBF in the left superior temporal lobe and right middle frontal gyrus—areas associated with attention and executive functions—compared to their typically developing peers. This reduction in blood flow suggests that children with ADHD may experience deficiencies in attention and executive functioning.

Age-specific comparisons showed no significant differences in cerebral blood flow between ADHD and typically developing children aged six to seven. However, children with ADHD in the eight to nine and 10 to 12 age groups exhibited significantly lower blood flow in certain brain regions compared to their peers. 

This indicates that the developmental trajectory of brain function in children with ADHD diverges from that of typically developing children, with critical changes occurring between ages seven and eight. This period may mark a significant point for the emergence or intensification of ADHD symptoms, highlighting its importance in the development of executive function.

For eight to nine-year-old children with ADHD, lower blood flow was notably observed in the left postcentral gyrus, which is associated with motor functions, and the left middle frontal gyrus, which is related to executive functions. This suggests that children with ADHD in this age group may struggle more with concentration and executive tasks.

In children aged 10 to 12 with ADHD, significantly lower blood flow was detected in the left superior occipital gyrus, which is involved in visual processing and spatial cognition. This implies that children with ADHD in this age group may have impaired visual information processing and spatial cognitive abilities compared to their typically developing peers.

Professor Kim said this study is significant as it provides evidence of distinct inflection points in the functional brain development of children with ADHD compared to typically developing children. “The differences in cerebral blood flow by age offer foundational data for understanding the developmental characteristics of ADHD and developing age-specific treatment strategies,” he said.

This research was supported by the National Research Foundation (NRF), funded by the Korean Government, and by a grant of the R&D project, funded by the National Center for Mental Health.

The findings were published in the latest issue of Scientific Reports, a sister journal of Nature.