A case-control study was conducted, including children diagnosed with ADHD at the outpatient clinic of Peking University Sixth Hospital from July 2015 to December 2019 as the ADHD group, and typically developing schoolchildren from January to December 2021 as the healthy control group. Both groups underwent pseudo-continuous ASL (pCASL) scanning to measure CBF, and executive function was assessed using the parent version of the Behavior Rating Inventory of Executive Function (BRIEF). Differences in CBF between ADHD children and healthy controls were compared. For brain regions showing significant group differences, CBF values were extracted and linear regression models were constructed with BRIEF scores to further explore the relationship between regional CBF and executive function.

A total of 134 boys with ADHD were included[83 with ADHD predominantly inattentive subtype (ADHD-I) and 51 with ADHD combined subtype (ADHD-C)], along with 25 healthy control boys. Intergroup comparisons revealed that the CBF in the left middle temporal gyrus was significantly lower in ADHD-C children compared to both ADHD-I children (P=0.010) and healthy controls (P < 0.001), while no significant difference was observed between ADHD-I children and healthy controls (P=0.280). After adjusting for age and total IQ scores, the linear regression model showed that the CBF in the left middle temporal gyrus of ADHD-C children was negatively correlated with the planning/organization score on the BRIEF (β=-0.062, P=0.030).

The CBF in the left middle temporal gyrus of boys with ADHD-C is significantly lower than that of boys with ADHD-I and healthy controls. This reduced regional CBF may be associated with executive function deficits in organization and planning abilities in ADHD-C, providing new insights into the neurobiological mechanisms underlying ADHD subtypes.