The ADHD vs. Non-ADHD Brain

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder. This means there are differences in the ADHD brain that affect a child’s development. ADHD does not influence intelligence. It does, however, affect a person's ability to regulate attention and emotions, and it results in hyperactivity and impulsivity as well as organization problems.

While it is classified as a condition, more recent thinking views it as a form of neurodiversity. People with ADHD brain's process information differently, but that represents a normal variation rather than a disorder that needs to be 'cured.' This neurodiversity perspective emphasizes recognizing these differences and valuing strengths instead of focusing solely on challenges or deficits. 

Rather than trying to change ADHD traits to fit into a neurotypical world, this perspective stresses the importance of accommodations and support to help people thrive.

Differences in the ADHD Brain

ADHD has come under a lot of scrutiny over the past few decades, contributing to public misperceptions and stigma. In the past, some naysayers questioned if it was real or said a lack of motivation, willpower, or bad parenting caused it. Then, there was the explosion of stories suggesting that ADHD was overdiagnosed and overmedicated.

None of which is true, of course, but if you or your child has ADHD, you can feel vulnerable to these types of comments.

The differences can be divided into three areas: structure, function, and chemistry.

ADHD vs. Non-ADHD Brain Structure

For many years, research showed there were clear structural differences in the ADHD brain. The largest review ever of ADHD patient brain scans was carried out at Radboud University Nijmegen Medical Centre and published in 2018.

Researchers reported that people with ADHD had smaller brain volume in five subcortical areas, and their total brain size was smaller, too. These differences were greater in children and less in adults.

Another interesting finding was that the amygdala and hippocampus are smaller in the brains of people with ADHD. These areas are responsible for emotional processing and impulsivity and had previously not been definitively connected to ADHD.

ADHD vs. Non-ADHD Brain Function

There are several types of brain imaging techniques that allow researchers to study how the ADHD brain operates and functions. These include:

• Functional magnetic resonance imaging (fMRI)
• Positron emission tomography (PET)
• Single-photon emission computer tomography (SPECT)

There are alterations in blood flow to various areas of the brains in people with ADHD compared to people who do not have ADHD, including decreased blood flow to certain prefrontal areas. Decreased blood flow indicates decreased brain activity.

The prefrontal area of the brain houses the executive functions, which are responsible for many tasks, including planning, organizing, paying attention, remembering, and emotional reactions.

Evidence also suggests that ADHD may be related to dysfunctional brain connectivity. Research using resting-state MRIs suggests that individuals with ADHD may have increased functional connectivity in certain regions of the brain.

ADHD vs. Non-ADHD Brain Chemistry

The brain is a busy communication network where messages are relayed from one neuron (brain cell) to the next. There is a gap between neurons, which is called a synapse. In order for the message to be passed along, the synapse needs to be filled with a neurotransmitter. Neurotransmitters are chemical messengers, and each one is responsible for different functions.

The key neurotransmitters for ADHD are dopamine and noradrenaline. In the ADHD brain, there is dysregulation of the dopamine system. For example, there is either too little dopamine, not enough receptors for it, or the dopamine is not being used efficiently.

How Is ADHD Diagnosed?

Brain scans cannot be used to diagnose ADHD. There is no objective test to diagnose ADHD. The diagnosis of ADHD requires a full evaluation by a qualified doctor, psychologist, or psychiatrist. Diagnosis includes:

• An in-depth interview with the patient
• A review of school reports and medical history
• Tests to measure attention, distractibility, and memory

While PET and fMRI scans can be useful for research, they really only give an insight into how the brain is functioning at the moment the test was performed. Brain scans do not take into account how the brain operates in different situations, unlike a clinical test during a detailed interview.

In addition, the scan data that has been studied is generally based on group averages and may not apply to any particular individual. The results have not been normed, which is when large quantities of data are gathered and compared.

Takeaways

ADHD is diagnosed as a neurodevelopmental condition, but it is important to remember that it represents a normal variation in brain structure, function, and chemistry. These differences can create challenges in your life, but that doesn't mean that they are something that needs to be "cured." ADHD also comes with strengths.

Understanding the underlying causes of your ADHD traits can be validating--and give you a place to start when it comes to managing some of the challenges you'll experience living in a society designed for neurotypical brains. Getting an accurate diagnosis is a great place to start. Depending on your unique experience, you may find that medications, therapy, ADHD coaching, accommodations, and social support can help.