What Structures Are Smaller in ADHD Brains? 

Research using neuroimaging consistently shows that certain ADHD brain structures are smaller in volume compared to those in neurotypical individuals. These structural abnormalities are most often seen in regions responsible for attention, impulse control, and emotional regulation, helping to explain many of the core symptoms of ADHD. 

Studies have highlighted reduced volume in the prefrontal cortex, basal ganglia, amygdala, and cerebellum, all crucial for managing behaviour, emotion, and focus. While these changes are typically subtle, large-scale scans and MRI-based studies have confirmed that these differences are consistent across age groups. Although brain size alone cannot be used for diagnosis, it adds to the evidence that ADHD is a neurodevelopmental condition rooted in biology. 

Key Brain Structures Affected in ADHD 

Understanding which parts of the brain are consistently smaller in people with ADHD helps explain both symptoms and possible treatment approaches. 

Prefrontal Cortex; Focus and Planning 

This region is often smaller in individuals with ADHD and is involved in decision-making, attention, and organising thoughts. When underactive, it may cause poor concentration or impulsivity. Stimulant medication can enhance activity, while CBT provides structure and strategies for managing tasks. 

Basal Ganglia; Movement and Control 

The basal ganglia help regulate movement and emotional responses. Structural changes here are linked to restlessness or poor self-control. Medication can improve balance in this system, while behavioural therapy supports coping skills. 

Visit providers like ADHD Certify for personal consultations to better understand how brain imaging can inform ADHD treatment.  

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to ADHD brain imaging findings .