The ADHD Brain vs. the Non-ADHD Brain

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects a person's ability to regulate attention and emotions. This can lead to hyperactivity, impulsivity, and organizational challenges.

Brain Structure

Individuals with ADHD have smaller brain volume in several subcortical areas, as well as a smaller overall brain size. These differences are more pronounced in children and less significant in adults. Additionally, the amygdala and hippocampus, regions responsible for emotional processing and impulsivity, are smaller in the brains of individuals with ADHD.

Brain Function

Functional imaging techniques have shown alterations in blood flow to various brain regions in individuals with ADHD. They have decreased blood flow in certain prefrontal areas, which are responsible for executive functions such as planning, organizing, paying attention, remembering, and emotional reactions.

Research also suggests that ADHD may be related to dysfunctional brain connectivity. Individuals with ADHD may exhibit increased functional connectivity in certain brain regions, suggesting that information is processed differently compared to individuals without ADHD.

Brain Chemistry

The primary neurotransmitters involved in ADHD are dopamine and noradrenaline. Individuals with ADHD often have dysregulation of the dopamine system, with either insufficient dopamine, a lack of dopamine receptors, or inefficient utilization of dopamine. Stimulant medications used to treat ADHD work by increasing dopamine production or prolonging its presence in the synapses.

Diagnosis of ADHD

Brain scans cannot be used to diagnose ADHD. Diagnosis requires a comprehensive evaluation by a qualified healthcare professional, such as a doctor, psychiatrist, or psychologist. The evaluation includes an in-depth interview with the patient, a review of school reports and medical history, and tests to assess attention, distractibility, and memory. The clinician will determine if the diagnostic criteria for ADHD, as outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), are met.

While PET and MRI scans can be valuable for research purposes, they provide limited insight into brain functioning in specific situations. Clinical interviews and assessments offer a more comprehensive understanding of an individual's presentation and symptoms. Additionally, scan data is often based on group averages and may not accurately reflect the brain functioning of a particular individual. Norms, established through the collection and comparison of large amounts of data, are not yet available for ADHD brain scans.