What Neurochemical Differences Are Seen in ADHD Brain Scans? 

Neuroimaging studies show that ADHD neurochemical differences involve altered levels and functioning of neurotransmitters such as dopamine (DA), and in some cases noradrenaline and serotonin. These changes in brain chemistry, observed via imaging techniques like PET and SPECT, help explain many symptoms of ADHD, from inattention to impulsivity.  

One of the clearest findings involves dopamine regulation: ADHD brains often show increased dopamine transporter (DAT) activity, which may lead to faster removal of dopamine from the synapse. PET studies report reduced dopamine receptor binding in specific brain regions (e.g. in the basal ganglia, prefrontal cortex) in untreated ADHD subjects. Some imaging work also points to lower glucose metabolism in prefrontal regions and the anterior cingulate cortex, which suggests reduced neuronal activity in those areas. Beyond dopamine, there is emerging but less consistent evidence for involvement of noradrenergic and serotonergic systems in emotion regulation and impulsivity.  

Common Symptoms & Imaging Correlates 

Below are symptoms commonly linked to these neurochemical findings, and how understanding them can guide treatment: 

Inattention, Motivational Deficits & Difficulty Sustaining Reward 

When DAT activity is elevated, or dopamine receptor binding is reduced, individuals may find tasks that are unrewarding harder to stay focused on. Medication (especially stimulants) works by increasing dopamine in synapses and modulating transporter activity. Behavioural therapy or coaching can help by building motivation, structuring reward systems, and helping with sustained engagement. 

Impulsivity & Emotional Reactivity 

Altered dopamine and possibly serotonin levels in brain chemistry may reduce impulse control and raise emotional responses. Imaging reveals lower receptor binding or dysregulated neurotransmitter turnover in these circuits. Medication can correct or compensate for these imbalances. CBT offers tools for recognising triggers, improving emotional regulation, and developing self‑control strategies. 

These imaging findings don’t function as standalone diagnostic tools, but they deepen our understanding of the biological basis of ADHD.  

Visit providers like ADHD Certify for personal consultations informed by the latest in imaging and neurochemical research. 

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