Written by Dr. Tara Boustany, Pharm.D on
September 10, 2021
Written by Dr. Tara Boustany, Pharm.D on:

Medically Reviewed by our Medical Affairs Team

You may have been wondering to yourself, what parts of the brain does ADHD affect? What are the symptoms? What is it like to live with ADHD?

What should you do if you think your child might be diagnosed with ADHD or has a high chance of being diagnosed with ADHD?

We will answer all these questions and more in this blog post. So, let’s get started.

What is ADHD?

Attention Deficit Hyperactivity Disorder (ADHD) involves a number of problems that include inattentiveness, impulsivity, and hyperactivity. These three main issues can be seen throughout various parts of a person’s life, such as school or work.

Three Subtypes of ADHD

ADHD has three main subtypes, namely:

Predominantly Hyperactive/Impulsive Type

The predominantly hyperactive or impulsive type of ADHD is the most common.

Many people with ADHD (about 60-75%) exhibit hyperactivity and impulsiveness as their primary symptoms—meaning that these two issues stand out the most compared to inattentiveness.

Predominantly Inattentive Type

This type of ADHD primarily contains symptoms of inattention but not hyperactivity or impulsivity.

People with the predominantly inattentive type often show symptoms such as being easily distracted and forgetful.

Combined Type ADHD

The combined type of ADHD is a combination of the other two types—in which case, someone might have both hyperactivity/impulsivity and inattentiveness as their primary symptoms.

What parts of the brain does ADHD affect?

At this time, it is not known for sure what parts of the brain are most affected when someone has ADHD.

What we do know is that there are various connections in different areas of the brain that may be altered or underdeveloped due to factors such as genetics and environmental influences. 

We also know that there is a difference in brain activity levels between those with ADHD and those without.

Further, there are slight differences in the brain structures of those with ADHD compared to those without.  

Even with these differences, there is no one area of the brain that is 100% responsible for causing ADHD symptoms.  

However, research shows links between ADHD and various parts of the bain, such as the following:

Frontal Lobe

The frontal lobe is the most recently evolved part of the brain. The left and right lobes make up a significant portion of what we know as our “thinking” brain, where logical reasoning skills are located, among other things.

This area plays a role in executive functions such as planning, organizing, strategizing, paying attention to, and remembering details, among other things.

Prefrontal Cortex

The prefrontal cortex represents about 30% of the brain’s total mass. It is located just behind our forehead on both sides of the head.

What sets this area apart from most others in terms of ADHD research is that it has been shown to be relatively smaller in those with ADHD compared to people without the disorder.

Norepinephrine Transporter

One of the main neurotransmitters associated with a person’s ability to stay focused and control their behavior is called dopamine.

What affects this neurotransmitter? The answer may be something you have heard about before, norepinephrine—a neurotransmitter that can be seen as the brain’s “adrenaline.”

The reuptake of dopamine (or norepinephrine) and serotonin in the brain is also influenced by something called a transporter. What does this mean? It means there are proteins on our cells’ surfaces that help move things inside those same cells.

This transporter is called the norepinephrine transporter, and it helps move excess dopamine back into brain cells after they have been released.

What you should know about this process is that if there are issues with the norepinephrine transport protein or its genes, then ADHD symptoms may occur even more so than usual.

Cerebellum

The cerebellum is the section of our brain located roughly behind and below your ear.

What makes this area so unique from other areas in terms of ADHD? The answer may be its role as a regulator or “governor” for better control over motor movements, balance, coordination, and a host of other things that involve balance and coordination.

As you can see, there are various parts of the brain that ADHD may affect—although no one area is 100% associated with causing this disorder.

What we do know is that it appears to be related to neurotransmitter levels in areas such as the prefrontal cortex being underdeveloped or altered compared to those without ADHD.

What in the brain causes ADHD?

The causes of ADHD are still not certain, but there is strong evidence that both genetics and environmental stimuli play a role.

For instance, if an expectant mother has untreated anxiety or depression during pregnancy, it can affect the fetus’ brain development which could lead to symptoms of ADHD in children.

Further research also shows that low birth weight, exposure to lead at a young age, and premature birth can all contribute as well. 

When it comes to genetics, we know that ADHD does run in families, and research has shown nearly 70% of people with ADHD have a parent or sibling who also has the disorder. 

ADHD Symptoms

ADHD symptoms vary from person to person and may also change over time.

For instance, someone who is hyperactive when they are younger will likely become more inattentive as a teenager or young adult.

What causes these changes? It appears that certain parts of the brain do not fully develop until later years which could be why ADHD symptoms change over time.

In the end, it’s important to remember that ADHD is a disorder and not something someone can simply “grow out of” or ignore with good intentions. 

Now, here are the most common ADHD symptoms: 

Inattention

  • Often fails to pay close attention to details or makes careless mistakes in schoolwork, work, or other activities.
  • Has difficulty sustaining focus on tasks or play activities.
  • Does not seem to listen when spoken to directly.
  • Fails to follow through on instructions from others and fails to finish chores or tasks in the workplace (not due to oppositional behavior or failure to understand instructions).
  • Has difficulty organizing tasks and activities.
  • Avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework).
  • Loses things necessary for tasks or activities (e.g., toys, school assignments, pencils, books).
  • Easily distracted by extraneous stimuli.
  • Forgetful in daily activities.

Hyperactivity and Impulsivity

  • Fidgets with hands or feet or squirms in their seat (in adolescents or adults may be limited to subjective feelings of restlessness).
  • Has difficulty remaining seated when required to do so.
  • Runs about or climbs excessively in children; extreme restlessness in adults.
  • Difficulty engaging in leisure activities quietly.
  • Acts as if driven by a motor; is unable to be or uncomfortable being still for an extended time, as seen in movies, historical paintings, or photographs.
  • Talks excessively.
  • Blurts out answers before questions have been completed.
  • Difficulty waiting or taking turns (e.g., while playing games).

Recent studies also suggest that ADHD may affect the cerebellum in addition to areas of the brain linked with impulsivity and hyperactivity.

ADHD Brain vs. Regular Brain

There are some interesting differences between the brain of those with ADHD and those without, such as:

  • The frontal lobe is smaller in people with ADHD compared to those who do not have the disorder.
  • Structural changes appear on a neurological level (i.e., an MRI) that show less connectivity among various areas of the brain in children with ADHD.   
  • The overall density, weight, and volume of gray matter in the brain are lower in those with ADHD.  
  • Scientists also know that those with ADHD tend to have a smaller amygdala and nucleus accumbens (two areas of the brain involved in emotional processing). 

The most important thing to remember about the brain is that it can adapt and change, even up until old age.

What this means for those with ADHD is that treatment may have a greater chance of being effective because the brain’s neural pathways are still forming—and not hardwired as in someone without the disorder.

How does ADHD affect learning?

The most common learning disability associated with ADHD is reading. 

However, many people who have ADHD and a high IQ score still struggle to perform well at school or work due to the disorder’s impact on executive functioning—or impairment of cognitive skills, such as:

  • planning
  • organizing
  • prioritizing tasks and activities
  • managing time effectively
  • staying motivated
  • utilizing working memory (i.e., the ability to remember instructions while completing a task).

Also, people with ADHD often have trouble with the following:

  • Understanding information as it is presented.
  • Processing auditory information quickly enough to grasp concepts.
  • Staying focused during lectures or lengthy reading assignments.
  • Organizing materials such that they are where they need them when they need them.
  • Keeping track of assignments and due dates.
  • Utilizing organizational tools such as planners or calendars.

It is important to be aware of the potential effects ADHD may have on learning; however, it is equally (if not more) important for adults who think they might have ADHD to seek medical attention regardless of how well they did in school.

Though some people who have ADHD may not have a learning disability, this does not mean that they are unintelligent.

In fact, many people with ADHD go on to earn college degrees and often achieve success in their chosen fields!

What is important for those with the disorder is getting proper treatment to overcome any potential obstacles associated with executive functioning deficits.

How does ADHD affect the brain in adults?

Some adults with ADHD do not develop the disorder until they are in their 30s, 40s, or even older.

This makes sense, given that the brain is still developing into early adulthood. What this also means for you—if you think you might have ADHD or know someone who does—is that there may be more than one type of ADHD.

Inattentive ADHD Types vs. Hyperactive-Impulsive ADHD Type

One study found that adults with the inattentive type of ADHD generally have smaller brain volumes than those who were hyperactive and impulsive.

What this also tells us is that different types (or not so visible symptoms) of a disorder can cause genuine physical changes in the brain.

The good news is that these physical differences are not necessarily permanent if you receive proper treatment for your symptoms.  

The Bottom Line

What all of these findings on ADHD and the brain tell us is that there are real physical changes in the brains of those with ADHD.

This does not mean, however, that people who have been diagnosed with this disorder cannot function normally or go on to live fulfilling lives!

Remember that it’s important to understand how your brain works so that you can overcome the potential obstacles that you may face in your life as someone who has ADHD.

If you are interested in learning more about the brain and the ADHD condition, especially about effective treatment options that suit you or someone you love who has ADHD, take this ADHD quiz today.

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