Is ADHD a Mental Illness?

Medically Reviewed By Yalda Safai, MD, MPH
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ADHD is a condition in which you may experience attention difficulty, hyperactivity, and impulsivity. Many doctors consider ADHD to be a mental illness with behavioral symptoms linked to brain abnormalities.  The U.S. Department of Health & Human Services defines attention deficit hyperactivity disorder (ADHD) as a behavioral disorder. However, the National Alliance on Mental Illnesses (NAMI) does list ADHD as a mental health condition.

Understanding the specific definition of ADHD might seem confusing, but this article will take a closer look at what ADHD is. It will also explain how you define a mental illness and the difference between an illness and a disorder. It will also cover some of the ways doctors diagnose and treat ADHD. 

What is ADHD? 

child in school
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ADHD is a disorder most known for the symptoms of hyperactivity, impulsivity, and difficulty paying attention. Doctors typically recognize the disorder in childhood, but adults may have ADHD as well.

The Centers for Disease Control and Prevention (CDC) explains that ADHD is a very common neurodevelopmental disorder in children. 

A neurodevelopmental disorder stems from abnormalities in the brain. Brain abnormalities then lead to some of the trademark symptoms of the disorder, such as difficulty focusing. 

Other neurodevelopmental disorders include:

It is common for many neurodevelopmental disorders to overlap, so doctors diagnose each one based on your individual symptoms. 

Visit our hub to read more about ADHD.

What are the signs of ADHD? 

ADHD symptoms fall into three main categories:

  1. Hyperactivity
  2. Impulsivity
  3. Difficulty focusing and paying attention

Each of these symptoms can bring its own signs. People with ADHD may have a combination of different symptoms between all three categories. 

Alternatively, someone with ADHD might have more symptoms in one category than another. 

Hyperactivity ADHD symptoms

Hyperactivity is a “classic” sign that many people associate with ADHD. Hyperactivity can look like: 

  • not being able to sit still
  • fidgeting and squirming while seated
  • leaving the area without permission, such as leaving your seat during class
  • any activity that is inappropriate for your setting, such as climbing or scaling when the teacher asks you not to
  • difficulty playing quietly
  • excessive talking 

Impulsivity ADHD symptoms

Impulsivity in ADHD refers to the inability to control your own behaviors. This might look like: 

  • interrupting
  • blurting out answers and talking out of turn
  • not being able to wait your turn

Inattentive ADHD symptoms

Difficulty focusing and paying attention is a hallmark sign of ADHD. This can be a challenging symptom for people with ADHD. You may try very hard to pay attention, only to be unable to do so because of abnormalities in the brain. This can lead to a cycle of shame and blame, which in turn can make symptoms worse. 

Inattentive symptoms can look like: 

  • not completing assigned tasks
  • difficulty organizing
  • inability to manage time
  • inability to focus or give full attention to tasks
  • losing things such as schoolwork, pencils, or other everyday objects
  • being easily distracted 
  • extreme procrastination 

Read more about the signs of ADHD.

Is ADHD a mental illness?

Doctors do consider ADHD to be a mental illness as it falls under the American Psychiatric Association’s (APA) definition. The APA describes a mental illness as a health condition that affects changes in emotion, thinking, or behavior. 

However, it is important to remember that ADHD is also a neurodevelopmental disorder. Brain abnormalities could cause the symptoms of ADHD, meaning that it is also a physical medical disorder. 

What is a mental illness?

The APA explains that mental illness is a medical condition, just like physical disorders such as heart disease or diabetes. An estimated 1 in 5 Americans have some form of mental illness. 

According to the APA, you can identify a mental illness when it leads to:

  • significant changes in how you think, regulate or express emotions, or behave
  • distressing symptoms
  • interruptions in your ability to function at work, in society, or within your family unit

Everyone can experience temporary mental health disruptions. However, any extreme or lasting disruption to things such as your ability to function or work may be a sign of a mental illness. 

Illness vs. disorder 

An illness typically refers to a clinical diagnosis with clear criteria that you can measure or identify. For instance, someone with the illness of diabetes has clinically identifiable data that marks their disease, such as elevated blood sugar and decreased insulin function. 

A disorder, on the other hand, may not have clearly defined markers to identify it as a disease. Instead, a disorder has symptoms that are usually associated with the condition. For instance, autism is a disorder with certain behaviors associated with it. 

Similarly, ADHD is a disorder that doctors cannot detect through a lab or blood test. However, it does have certain traits and behaviors that link to the condition. 

When it comes to describing a mental illness, however, there is no specific definition. Doctors consider it to be any type of disorder that causes significant distress, impact, or behavioral changes in your life. Doctors can diagnose a mental illness even without clear clinical markings such as bloodwork or a lab test.

In that way, ADHD is both a mental illness and a behavioral disorder. 

How do you diagnose ADHD? 

There is no single test for ADHD, so doctors diagnose the condition by signs and symptoms. This may include:

  • observing the individual with suspected ADHD
  • consulting with teachers or caregivers
  • parental accounts of how the child acts
  • talking directly with the person
  • working alongside a mental health team to come up with a diagnosis

In some cases, doctors may also ask a child or adult to perform some tests or tasks. These test your ability to focus or prioritize, which may help pinpoint an ADHD diagnosis. 

How do you treat ADHD?

Doctors treat ADHD through a combination of different therapies that include:

  • medications, such as non-stimulants and antidepressants
  • behavioral therapy
  • education and self-management programs for work and school 
  • physical activity
  • proper nutrition
  • limiting screen time

Additionally, the NAMI explains that ADHD often coincides with another mental illness or behavioral disorder. Treating any other conditions you or your child may have can also help with ADHD symptoms. 

Approximately 2 out of 3 children with ADHD also have another type of health disorder. 


ADHD is a type of mental illness that is also classified as a neurodevelopmental disorder. That means that doctors consider ADHD to link to physical brain abnormalities. The abnormalities lead to behavioral changes that impact your ability to focus, concentrate, and carry out essential tasks. 

People with ADHD often are hyperactive, which means they have difficulty sitting still or not fidgeting. They may do things such as run away or climb in inappropriate settings. Someone with ADHD may also have trouble with impulse control. This can cause them to do things such as interrupting others or speaking out of turn. Another common ADHD symptom is inattention. Someone with ADHD may have trouble focusing, paying attention, and carrying out tasks as they should. 

There is no one test for ADHD. Doctors will diagnose the condition by your symptoms. They may also consult with caregivers and a mental health team. A treatment plan for someone with ADHD usually involves a combination of medication, behavioral therapies, and educational and self-management plans to alter behavior. 

Getting enough sleep, eating a balanced diet, and leading a healthy lifestyle with enough physical activity can also help manage ADHD symptoms. 

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Medical Reviewer: Yalda Safai, MD, MPH
Last Review Date: 2022 Oct 10
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