Imaging data from the IMAGEN study, attracted researchers at the University of Vermont to explore the elusive cause of attention-deficit/hyperactivity disorder (ADHD). Clinicians still don’t fully understand the underlying causes of this common condition. Now a brain marker may be on the horizon. The researchers reviewed psychopathology and imaging data from 1538 adolescents. The data included parent ratings of ADHD symptoms collected through the Strengths and Difficulties Questionnaire (SDQ), and self-reports from the adolescents in the study through the youth version of the SDQ. The team also derived ADHD symptom counts from parent interviews – and then related ADHD symptom counts to brain structure. When they overlaid the imaging results from all of their analyses, they found that reported ADHD symptoms were related to reduced gray matter volume in an area of the prefrontal cortex, the ventromedial prefrontal cortex (vmPFC). This relationship was particularly true for symptoms of inattention. This area also related to reaction time variability, an objective behavioral measure of attention that has been previously associated with ADHD. The findings could affect future ADHD interventions to strengthen this region of the brain.