Cerebral Blood Flow Characteristics and Executive Function in Different Subtypes of Attention Deficit Hyperactivity Disorder

Objective: This study aims to explore the differences in cerebral blood flow (CBF) among different subtypes of Attention Deficit and Hyperactivity Disorder (ADHD) predominantly inattentive type (ADHD-I) and combined type (ADHD-C) in children using Arterial Spin Labeling (ASL). Furthermore, it investigates the relationship between these differences and executive functions to gain a deeper understanding of the neurobiological basis of ADHD. Methods: The study included 159 male participants who completed pseudo-continuous ASL (pcASL) scans, comprising 83 children with ADHD-I, 51 children with ADHD-C, and 25 healthy controls (HC). The ecological executive function of the patients was assessed using the Behavior Rating Inventory of Executive Function-Parent Form (BRIEF). Analysis of covariance (ANCOVA) was used to explore differences in CBF among the three groups, with post hoc tests conducted using Dunn’s test. For brain regions showing intergroup differences, the corresponding CBF values were extracted and regression models were constructed with the BRIEF scores to further clarify the relationship between regional CBF differences and executive function. Results: Significant differences in CBF were observed in the left middle temporal gyrus among the ADHD-I, ADHD-C, and HC groups (Gaussian Random Field， GRF correction: voxel-level P <0.001, cluster-level P <0.05, bilateral test). Dunn’s post hoc test (Bonferroni correction P <0.05) showed significant differences between the ADHD-C and HC groups (P = 0.000) and between the ADHD-C and ADHD-I groups (P = 0.01), with the ADHD-I group showing lower local CBF compared to the other two groups. However, no significant differences were found between the ADHD-I and HC groups. Regression analysis with the BRIEF scores revealed a significant correlation between CBF in the ADHD-C group and planning/organization scores (b = -0.062, P = 0.03).Conclusion: There are significant differences in local cerebral blood flow between the ADHD-I and ADHD-C subtypes. The CBF in the left middle temporal gyrus is significantly lower in the ADHD-C group compared to the ADHD-I and HC groups. The reduced local CBF may be related to the executive function deficits in the ADHD-C subtype, particularly in organizational and planning abilities. No significant differences in local CBF were found between the ADHD-I and HC groups. These findings provide new insights into the neurobiological mechanisms of ADHD subtypes.