The Science Behind ADHD: What’s Really Happening in the Brain

Understanding how ADHD (Attention-Deficit/Hyperactivity Disorder) affects the brain helps us see not only why its symptoms occur, but also how to manage them and harness its strengths.

““It’s not that you can’t focus, your brain just plays by its own rules”. ”

Why does ADHD exist?

First, let’s ask ourselves, why does neurodiversity, such as ADHD occur in the first place?

Researchers theorise that the answer likely lies in our evolutionary past. Humans naturally develop in a diverse manner, this gives us collective survival advantages as a species. Imagine a tribe where each member has a unique strength: one skilled at hunting, one at gathering, another at sewing or cooking. Such a group likely thrives more than one where everyone is merely average at everything.

Now picture a few individuals who are especially alert to change and are quick to notice a rival tribe on the horizon or movement in the grass that signals danger. In an ancient environment, being attuned to novelty and threat could have been lifesaving.

ADHD in modern society

Fast forward to today, we live in a society where we are expected to sit through classes or in front of computers with spreadsheets open for 6+ hours a day. A brain that is wired to interact with novel stimuli, be highly curious and active may feel out of place.

ADHD traits in this situation which may have once been adaptive may now be a disadvantage. The heightened awareness may now be seen as greater distractibility.  Those who are novelty seeking may be seen as having a short-attention span. These traits that were once adaptive may now lead to issues in a society with different demands.

Unfortunately, this mismatch often leads to misunderstandings. People with ADHD are sometimes labelled “lazy” or “undisciplined,” despite expending far more effort to focus than others. Over time, these experiences can contribute to anxiety, low self-esteem, and depression.

Some individuals turn to self-medicating with caffeine, nicotine, or marijuana to manage symptoms. However, these can interfere with sleep and mood, ultimately worsening ADHD-related difficulties.

Brain Differences between ADHD brains and Non-ADHD Brains

There are varying differences found by researchers in the brain which may be responsible for ADHD symptoms:

Lower levels of norepinephrine and dopamine.

ADHD is associated with lower activity in neurotransmitters such as dopamine and norepinephrine, both crucial for motivation, attention, and impulse control. Dopamine also regulates our reward system, meaning tasks that feel mundane to others may feel unbearably unstimulating to someone with ADHD.

A classic animal study found that mice with reduced dopamine showed far less motivation to eat, even when food was available. This highlights how difficult it can be for individuals with ADHD to engage in low-stimulation tasks for extended periods.

Less active prefrontal cortex (PFC)

The Prefrontal cortex (PFC) is the front part of the brain, right behind your forehead which is responsible for planning, impulse control and working memory. In individuals with ADHD, the PFC is found to be either less active or matures later (typically 2-3 years on average for children) compared to neurotypical individuals.

This helps explain why people with ADHD may need external supports like planners, reminders, or structured routines to stay organised, and why impulses (like blurting out thoughts or jumping between tasks) can be harder to suppress.

Stronger local connectivity, weaker long-range connectivity

Brain scans reveal that people with ADHD often have stronger local connectivity (fast, short-distance communication between nearby brain areas) and weaker long-range connectivity (communication between distant regions like the prefrontal cortex and the basal ganglia) .

This different wiring of the brain can lead to quicker intuitive associations and may appear as being creative and quick-thinking and even humour. However, this may come at a cost of greater forgetfulness and difficulty maintain consistent routines.

Amygdala and Limbic System

The Amygdala and limbic system are responsible for emotional regulation and activation of your ‘fight or flight’ response. In individuals with ADHD, these systems are more reactive, which can result in greater and quicker shifts in emotional state.

Children with ADHD are often described as “sensitive,” which, without understanding, can invite more negative feedback and fewer positive reinforcements. Over time, this emotional reactivity may contribute to the development of anxiety or depression.

Professional Support

Given these neurobiological differences and the challenges of living in a society not designed for ADHD brains, professional support can be invaluable.

Therapists can help individuals:

• Understand how ADHD manifests for them personally and any comorbid issues

• Develop self-compassion and adaptive coping strategies

• Build skills for planning, focus, and emotional regulation

 At Luminosity, our aim is to help you understand your ADHD, recognise your symptoms and work on skills and strategies to help you manage these and live a more fulfilled life. Our therapists work from a neuro-affirming approach.

**The content provided is general advice and should not replace individualised treatment. If you require immediate support, contact your local emergency department or a mental health crisis hotline (1800 011 511).

References

Arnsten, A. F. T. (2009). The emerging neurobiology of attention deficit hyperactivity disorder: The key role of the prefrontal association cortex. The Journal of Pediatrics, 154(5), S43–S50. https://doi.org/10.1016/j.jpeds.2009.01.018

Columbia University Department of Psychiatry. (n.d.). Evolution and ADHD. https://www.columbiapsychiatry.org/research/research-areas/child-and-adolescent-psychiatry/sultan-lab-mental-health-informatics/research-areas/evolutionary-psychiatry/evolution-and-adhd

Cortese, S. (2010). Dopamine reward pathway in adult ADHD. JAMA, 303(3), 232. https://doi.org/10.1001/jama.2009.1999

del Campo, N., Fryer, T. D., Hong, Y. T., Smith, R., Brichard, L., Acosta-Cabronero, J., Chamberlain, S. R., Rogers, R. D., Williams, S. C. R., & Rubia, K. (2011). The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder. Biological Psychiatry, 69(12), e145–e157. https://doi.org/10.1016/j.biopsych.2011.02.036

Szczypka, M. S., Rainey, M. A., Kim, D. S., Alaynick, W. A., Marck, B. T., Matsumoto, A. M., & Palmiter, R. D. (1999). Feeding behavior in dopamine-deficient mice. Proceedings of the National Academy of Sciences, 96(21), 12138–12143. https://doi.org/10.1073/pnas.96.21.12138

Tajima-Pozo, K., Yus, M., Ruiz-Manrique, G., Lewczuk, A., Arrazola, J., & Montañes-Rada, F. (2018). Amygdala abnormalities in adults with ADHD. Journal of Attention Disorders, 22(7), 671–678. https://doi.org/10.1177/1087054716629213