An illustrated brain depicting ADHD and the struggles.

The Neuroscience of ADHD 

Liadan Gunter
February 2, 2024
December 11, 2023

The world is fast-paced. There’s no doubt about it. Meetings, project deadlines, kid drop-offs, social gatherings…the list goes on and on. Life can be chaotic and require us to juggle a variety of tasks on an everyday basis. In order for us to succeed, we need to have the ability to direct our attention and focus on our tasks at hand. In the midst of all these commitments, this ability can be really challenging! However, for some of us, it may be more difficult than for others. 

We all can struggle with focusing our attention from time to time, but not all cases of inattention are cause for concern. Perhaps you forgot to put the laundry away and left a task uncompleted midway through. You may joke to others, “I have ADHD.” Despite the fact that culturally, we shouldn’t joke about these conditions, which is a conversation for another time, many people use the term to describe normal instances of forgetfulness or distractibility. This can leave many confused about what ADHD actually is. Some may ponder: “Do I actually have ADHD, or do I merely struggle to limit distractions?” Where is this line between normal levels of inattention, and when is it truly a cause for concern? 

The Difference Between Being Distracted and ADHD

Attention-Deficit/Hyperactivity Disorder (ADHD) is a psychiatric condition that affects important areas of life, such as one’s social relationships and academic/professional performance, due to an inability to focus, impulsivity, and hyperactivity. It is a developmental disorder, meaning that its onset occurs in childhood but persists over a lifetime. Not everyone is diagnosed in childhood or adolescence, though. 

To a certain extent, we can all struggle with moments of inattention, but what makes this clinical is when one’s difficulties with concentration happen alongside impulsivity, hyperactivity, difficulty managing emotions, forgetfulness, and disorganization. Additionally, ADHD is characterized by a general feeling of being overwhelmed almost all of the time by one’s own thoughts and environment. 

In general, it’s easier to focus on tasks that we enjoy doing and more challenging to focus on tasks that we find unpleasant, or that are difficult. When one doesn’t have ADHD, they may still be easily distracted but can get back on track once they’ve either realized they’re distracted or removed the distraction from their environment. People with ADHD will still struggle to focus even if the distraction is removed. 

Being distracted may make work go slower or feed into procrastination, but being easily distracted doesn’t tend to prohibit neurotypical people from accomplishing tasks or fulfilling commitments, whereas ADHD severely impairs one’s functioning, making completing tasks and meeting commitments difficult to the point that their performance at work or school, or ability to maintain relationships becomes affected.  

How Is ADHD Diagnosed?

No physical or genetic test can be done to solely diagnose ADHD. Instead, ADHD is diagnosed by a mental health professional such as a physician, psychiatrist, or psychologist who conducts a clinical assessment. The assessment is based primarily on symptom evaluation. A detailed history of past and current functioning, standardized behavior rating scales, and information from family members or significant others who know the person well may also be considered. 

The clinical assessment performed is based upon symptom evaluation outlined by the Diagnostic and Statistical Manual of Mental Disorders, DSM-5. 

According to the DSM-5, for one to fulfill the diagnosis criteria, patients should:

  1. Have at least 6 (for children and adolescents), or 5 (for adults) out of 9 symptoms for a minimum of 6 months
  2. Symptoms appeared before the age of 12 
  3. Symptoms have caused impairments in living
  4. Symptoms affect different life contexts 

One key here is that ADHD symptoms must have been present in the individual before the age of 12 to be able to diagnose someone with this condition. This can, of course, make it tricky to diagnose, particularly if these behaviors went unnoticed in childhood initially. 

Genetics or Environment?

Genetics is considered the most important factor for developing ADHD. In fact, ADHD has a high heritability rate of 74%

That being said, the environment may also play a role. In fact, certain prenatal influences (such as exposure to certain chemicals during pregnancy), premature birth or low birth rate, environmental toxins, and even parenting can contribute to the development and severity of symptoms of ADHD. 

The Neuroscience Behind ADHD

Much of the research that has looked into ADHD has focused on which brain networks may be involved, and studies have implicated 3 primary brain networks.  

People with ADHD have been found to have atypical activity or connectivity in a variety of networks: 

  1. The Default Mode Network: a collection of brain regions that is primarily active during mind wandering, and less active when one is trying to complete a task, for example. Studies have found that people with ADHD have an atypical connectivity in this network, which is thought to be associated with distractibility. 
  1. Attention and Cognitive Control Network: involved in one’s ability to attend to stimuli and exert cognitive control. People with ADHD have been found to have less activity in these regions. Generally, when a healthy individual is completing a task, activity in the attention and cognitive control network increases while activity in the default mode network decreases. This helps someone decrease their mind wandering, and increase their attention. One hypothesis is that activity in the default mode network is dysregulated, which interferes with the function of networks involved in attention and cognitive control, making it much more difficult for one with ADHD to dampen their daydreaming so they can pay attention or exert cognitive control. 
  1. The Reward System has also been found to show atypical activity.  The consensus is that this activity may contribute to those with ADHD placing more value on short-term rewards versus long-term ones, ultimately affecting their ability to plan and make decisions. 

Neurotransmitters Are Also Implicated In ADHD

In general, no main cause of ADHD has been determined. However, varying levels of dopamine, norepinephrine, and serotonin have been implicated in ADHD and are thought to contribute to the severity of symptoms. 

It’s important to note the reward system includes some of the major dopamine pathways in the brain. In fact, as a neurotransmitter, dopamine is one of the main neurotransmitters often implicated in ADHD.

Treatment Methods

Many medications that are used to treat ADHD increase the transmission of dopamine and norepinephrine, and are stimulants. There are other non-stimulant medications that can be good options for those who can’t or don’t want to take stimulants. 

Other treatment methods include education, skills training, and counseling to help manage symptoms and learn to implement new behaviors. 

ADHD is a complex neurodevelopmental disorder that people may deal with throughout their life. I hope this post helps shed some light on the neuroscience behind ADHD and clarifies the difference between normal distractibility and ADHD. 

Ultimately, ADHD can be traced back to altered brain function. Although ADHD is multifaceted, it’s underscored by the interplay of genetic, environmental, and neurobiological factors that make diagnosing and understanding it that much more challenging. I hope that understanding a little more about the neuroscience behind ADHD and how difficult it is to diagnose can help destigmatize the condition and foster empathy for those who deal with its daily challenges.

Liadan Gunter
Liadan Gunter
Liadan Maire Gunter is a Coach, Behavioral Scientist, and Founder of The Rewiring Lens. She is trained in neuroscience, psychology, and anthropology, before creating her own path in the field of self-development. At Nivati, she works as a life coach and content writer where she bridges the gap between science and self-development. She also runs a company, The Rewiring Lens, aimed at bringing science-backed tools designed to rewire people’s brains so that they can create their best selves. There she co-hosts a podcast on the same subject.