Written by Dr. Tara Boustany, Pharm.D on
September 4, 2021
Written by Dr. Tara Boustany, Pharm.D on:

Medically Reviewed by our Medical Affairs Team

Have you lately noticed that you’ve had difficult thought processes and behaviors that are not generally normal with people around you? Do you suspect it could be ADHD?

This article will answer the most commonly asked questions, such as: how does ADHD affect the brain, what causes ADHD, how you can control it, and how to live with it—based on reliable research studies.

So, let’s get started.

What is ADHD Exactly?

ADHD stands for attention-deficit hyperactivity disorder. It is a neurological and psychiatric disorder that impacts how your brain processes information. ADHD often makes it difficult to regulate behavior, sustain focus, manage frustration, control impulses, and avoid distraction [1].

Three Subtypes of ADHD

There are three subtypes of ADHD: predominantly inattentive, predominantly hyperactive-impulsive, and a combination of the two.

Predominantly Inattentive Subtype (PINS) is typically easier to overlook than other forms of ADHD because people who have it often appear shy, day-dreamy, or spacey instead of disruptive.

They may sit quietly, but they are distracted by their own thoughts and have a hard time staying focused on any one thing.

Predominantly Hyperactive-Impulsive Subtype (PHINS) is the most common type of ADHD in children and adults [2].

People with this subtype tend to fidget or talk excessively. They are impulsive, which can mean they have trouble waiting for things they want or interrupt conversations.

Combination Subtype (COMB) has features of both the combined hyperactive/impulsive and inattentive subtypes of ADHD [2].

This type is often how ADHD presents itself clinically. People with this subtype generally experience both of the main features of ADHD—inattention and hyperactivity/impulsivity.

What does ADHD do to the brain?

How does ADHD affect the brain? Research shows how it affects the three regions of your brain: the prefrontal cortex, striatum, and cerebellum.

The Prefrontal Cortex is the front part of your brain that regulates behavior, personality expression, judgment, motivation—basically everything you do with emotions [3].

On the other hand, the striatum controls how you plan, how you act on those plans, and how you adapt to changing situations.

And the cerebellum is the part of your brain that helps control how quickly or slowly things happen [4].

People with ADHD have trouble filtering out unnecessary or irrelevant stimuli, which can make it harder to focus on what they want to focus on. 

They also tend to be more impulsive and impatient, making them less able to inhibit responses [5].

What causes ADHD?

Researchers are still learning how it is brought about, but they know that genetics plays a role.

Twin studies have shown that if one twin has ADHD, there’s an 80% chance the other will, too [6]. If you think of ADHD as caused by faulty wiring in your brain, this makes sense because identical twins have the same DNA code.

However, it is important to note that ADHD does not primarily arise from how you were raised (if your parents did something wrong with their parenting). 

Rather, how you are raised likely shapes how ADHD affects your life and how you express the symptoms, such as if a child becomes hyperactive or inattentive or both.

What part of the brain does ADHD affect?

People with ADHD have structural and functional differences in how their brains are wired. These brain changes are seen on fMRI, which means that scientists can see how the areas of your brain light up when you’re completing tasks or playing games versus how they look at rest [7].

The difference is most present—and evident to researchers—in three brain regions: the prefrontal cortex, striatum, and cerebellum [7].

The Prefrontal Cortex is responsible for how you feel about yourself. It helps you solve problems, control your emotions and impulses, plan ahead—essentially how you interact with others.

People with ADHD have a smaller prefrontal cortex than people without ADHD, which means it can’t filter out things like background noise or other distractions [8].

The Striatum is the part of your brain that helps you plan how to do something and how long it will take, make predictions about how well you’ll do on a task, and respond if something unexpected happens.

People with ADHD have trouble seeing how the different parts of a task fit together and how long it will take to complete [5].

The Cerebellum is responsible for how you process information, such as how quickly or slowly things happen. 

People with ADHD have trouble processing auditory information, leading them to get distracted by irrelevant stimuli like background noise [4].

Does ADHD affect brain size?

People with ADHD typically have a smaller brain volume in their frontal lobes. This is known as “cortical thinning” [8].

However, new research suggests that ADHD doesn’t affect how your brain cells grow and how they communicate—it’s the connections between them where things go wrong [9].

The prevailing theory of how ADHD affects the brain is that there are not enough connections between nerve cells, which makes it harder to process information and can lead to symptoms like hyperactivity [10].

Does ADHD affect how the brain works?

The short answer is yes.

People with ADHD have trouble making connections between how they feel and what happens around them. That means that if something good happens, it might not do much to lift their mood because they don’t notice how happy they are [1].

And when things get stressful, it can be challenging for people with ADHD to figure out how they’re feeling about a situation and how best to handle it [1].

A new study found that being impulsive or inattentive doesn’t mean that you have less brain activity. Instead, your brain is just under-recruiting regions responsible for paying attention while still using areas responsible for how you feel about something [11].

Does ADHD affect thinking?

A significant hallmark of ADHD is how much difficulty people have with concentration and impulse control.

The prefrontal cortex regulates how you think, plan, learn new ideas or skills and how well you can focus on something for an extended period of time [1].

People with ADHD have “under-connectivity” between the frontal lobe and other parts of the brain that are responsible for how you feel about something or how well you can focus [1].

When people have ADHD, they tend to take in more information than others and process it at a faster rate. 

That means when someone with ADHD looks at an object, they see everything about it rather than focusing on one aspect—something that makes it hard to focus on how he or she feels about something [12].

How does ADHD affect the brain of a child?

As a child with ADHD gets older, how their brain develops depends on how severe their symptoms are and how well they respond to treatment.

A young teen might show the same brain changes as an adult who has had ADHD for years [13].

But other research suggests that kids who have more impulse control problems at age 12 don’t necessarily show the same changes in their brain’s “white matter” as teens who don’t have ADHD [14].

That means how your child’s brain develops is influenced by how severe his symptoms are and how well he responds to treatment.

Studies suggest that kids with ADHD start off behind other children when it comes to how much their brains grow but eventually catch up to their peers as they get older [15].

How does ADHD affect the brain in adults?

The symptoms of ADHD change how the brain develops, but adults with ADHD can still learn new skills and ways to control how they react [1].

Studies suggest that “white matter” deep in the brain is less developed in people who have had ADHD for a long time. 

This means that how your child’s brain grows might influence how their adult brain develops [14].

However, new research suggests that how impulsive or inattentive you are doesn’t affect how your brain works—it’s the connections between nerve cells where things go wrong.

And ADHD might not lead to less activity in certain parts of the brain as was once thought—instead, there is simply under-recruitment of regions responsible for how you feel about something or how well you can focus [16].

How does ADHD affect learning?

The symptoms of ADHD can make it harder for people to focus or sit still, which makes learning how to read or how math works more difficult for children [17].

Also, people with ADHD are also less likely to try new things because they don’t want to risk making mistakes. And when something does go wrong, it’s easy for them to get frustrated and give up [18].

But don’t lose hope.

There’s a lot you can do to help your child at home and how they learn in school, like making sure they get enough sleep every night [19] and staying on top of their treatment plan with their healthcare provider [20].

How does ADHD affect the nervous system?

The nervous system includes how your brain and body communicate with each other.

People who have ADHD might be more sensitive to touch, taste, or smell [21].

That means how ADHD affects the nervous system is actually a symptom of how it affects how you feel about something.

And how ADHD affects the nervous system can also make it harder for people to control how they react.

People with ADHD are more likely to have problems managing their emotions [22].

That means that how you feel about something or how well you can focus on something is ultimately why ADHD affects the brain and how we communicate with our body in how ADHD affects how the body works.

How does ADHD affect relationships?

People with ADHD might be more sensitive to how others are feeling, which can make it hard for them to express their own feelings [23].

That means how the brain works of someone who has ADHD is directly linked to how they interact with other people.

The symptoms of ADHD also affect how well you listen and remember what your classmates or coworkers are saying and how well you can pay attention to what they’re doing [24].

That means how ADHD affects the brain is directly linked with how it affects how we communicate with others.

The symptoms of ADHD might make it harder for people to manage their emotions, which makes relationships more challenging [23].

The Bottom Line

In summary, how ADHD affects the brain is all about how it makes you feel and how well you can focus.

But with treatment, people who have ADHD can learn to control how they react. And research suggests that even though some parts of their brains might be different from others, individuals with ADHD never stop learning new skills [25].

Do you think you or someone you know might have ADHD? Take this ADHD Quiz today to find out!

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