Explainer: What is ADHD?

School was difficult for Makayla Caliendo when she was young. She remembers staring out the window while her classmates were paying attention in class. Some clothes, tags and socks were uncomfortable and left her unable to focus. She even had to repeat preschool.

“I left those early school years with less knowledge than my peers,” Caliendo wrote as a high-school senior in Attention magazine. That was back in 2021. Those experiences had “made me feel dumb.”

But Caliendo wasn’t — and isn’t — dumb. Her brain just works differently than most of her peers.

Caliendo has a condition known as attention deficit/hyperactivity disorder, or ADHD. It affects how people think, learn and process information. Although sometimes called a “disorder,” ADHD is actually a neurotype. That means it’s a natural — and fairly common — variation in how the brain develops.

Some 22 million people in the United States have been diagnosed with ADHD. This includes more than 6 million children.

People with ADHD produce a lower amount of some of the chemicals that brain cells use to communicate. One is dopamine. It affects motivation and mood. Another is norepinephrine (Nor-ep-ih-NEF-rin). It plays a role in attention and excitement.

These brain differences can make it harder for people with ADHD to focus on certain tasks when compared to folks without ADHD. People with ADHD may have trouble sitting still or controlling their emotions and actions.

Such traits are not always a problem, notes Jamal Williams at the University of Buffalo in New York. He studies the genetics behind ADHD. People have had traits linked to ADHD for a very long time. Recent research suggests ADHD-like behaviors, such as risk-taking and impulsivity, would have made people better foragers in ancient hunter-gatherer societies.

However, people today are expected to sit still in classes and offices. They may have to be quiet for hours at a time. This can make it difficult for people with ADHD to succeed in such environments.

Common ADHD traits

People with ADHD can show many different patterns of behaviors. Still, a few traits help experts identify ADHD and divide it into three types.

• Hyperactive: People with hyperactive ADHD tend to experience excessive restlessness. Someone may find it hard to stay still for long. Their mind might wander. They might be impulsive or make decisions without thinking about the consequences. 
• Inattentive: People with inattentive ADHD are easily distracted and forgetful. They may have trouble following directions and paying attention to details. (This is the type Caliendo was diagnosed with.)
• Combined: The most common type of ADHD, this combines some hyperactive and inattentive traits. Williams estimates that six in every 10 people with ADHD have this type.

Which traits an individual exhibits can depend on many factors. One is their genes. About 80 percent of people with ADHD have inherited genes that make them more likely to show ADHD traits. This makes ADHD the most inherited mental condition. 

Environmental factors may also play a role. Some evidence suggests infections or early-life exposure to lead or other toxic metals can affect ADHD. However, it’s not clear whether these factors cause ADHD directly.

How ADHD is diagnosed

Experts diagnose ADHD based on the behaviors people exhibit. These can include fidgeting one’s hands or feet, talking excessively or forgetting certain tasks and the tools needed to complete them.

Everyone may do these things at times. So finding it hard to concentrate now and then is no sure-fire sign of ADHD. To get this diagnosis, someone must show six or more characteristic traits. The traits also must be present for at least six months. And they must affect how someone functions in multiple settings, such as at home and at school.

Many types of professionals can make an ADHD diagnosis. “You could have a social worker, a school counselor, a pediatrician, a psychiatrist or a psychologist,” says Williams. People in each role will have somewhat different perspectives. So they may assess someone’s traits in different ways. For instance, a doctor may ask parents or a teacher to fill out a questionnaire about a child’s behaviors. A school counselor may interview a student or their parents to look for signs.

A child will likely be assessed only if someone thinks they see tell-tale groups of behaviors. If kids are not assessed, diagnoses may be delayed. More than half of people with ADHD won’t be diagnosed before age 14. 

And some groups are less likely to be evaluated than others.

Girls, for instance, are less likely than boys to be diagnosed. One reason: Girls with ADHD are more likely to show inattentive traits, such as frequent daydreaming. These tend to be less obvious than hyperactive traits, such as interrupting others. Even when girls do have hyperactive traits, these can be subtle. Girls may be highly sensitive to their emotions or have trouble concentrating on specific tasks.

Black, Asian and Hispanic children also are less likely than white kids to get an ADHD diagnosis. Some parents may be reluctant to have their children evaluated, says Sharon Saline. She’s a clinical psychologist in Massachusetts who writes and talks about ADHD. For kids who may already be facing racism, an ADHD diagnosis could reduce self-esteem and their mental well-being, she notes.

Even when evaluated, Black children are more likely to be diagnosed with a conduct disorder than ADHD. A conduct disorder is a pattern of hurtful behaviors, such as aggression or rule-breaking. These are often done on purpose and without remorse. Similar behaviors can show up in a person with ADHD — but for different reasons. Someone with ADHD may be acting without thinking about the consequences. And they may feel guilty once they understand how their actions have affected others.

The wrong diagnosis can make it hard to get the right support. It also can hurt a person’s self-esteem. That’s especially true if someone with ADHD wants to improve their behavior.

Williams and his team believe racial biases affect how Black kids are likely to be diagnosed. “If you have [a] white teacher with a Black student, the teacher may perceive behavior through a different cultural context,” he explains. Take a student who gets upset at not knowing the answer when called on in class. “It might be easier for a Black teacher to identify in a Black student that this is a kid who is having difficulty paying attention and maybe feels frustrated.”

Some misconceptions about ADHD

ADHD was first defined in the 1980s. Some people still think it’s not a real condition. But descriptions of ADHD traits can be found throughout history.

Take Thomas Edison. He’s known for inventing the light bulb and other cool gadgets. But he would get distracted by other projects before finishing one. His teachers also kicked him out of school when he couldn’t focus. These clues suggest Edison may have had ADHD.

People with ADHD also may be seen as lazy when they don’t complete a task or if they forget something. But this can stem from a brain primed for “novelty-seeking,” Saline says. The low levels of some signaling chemicals make it harder for the ADHD brain to focus on tasks that seem boring.

“It is no problem to play a game for two hours,” says Saline. “But it is a lot harder to do your homework if you do not like math. Or [to] take the trash out.”

ADHD behaviors that are viewed as problems in some settings can be useful in others, Williams points out. For instance, hyperactive and impulsive behaviors can help people with ADHD make connections between different topics. This can lead to more adaptive and creative ideas than may emerge in people with a more rigid way of thinking.

Also, when someone with ADHD finds a task that interests or challenges them, they might fixate on it. Such intense focus can allow them to become highly skilled or knowledgeable about their passion.

Swimmer Michael Phelps was diagnosed with ADHD when he was 9. As a kid, he loved to swim and went to the pool every day — even Christmas. His fixation helped him become very successful: He won 23 Olympic gold medals between 2004 and 2016.

ADHD treatment

ADHD can be treated with medicine. These drugs help to regulate levels of signaling chemicals in the brain. They can help reduce hyperactivity and boost attention. 

These drugs do not work for everyone, however. And they can cause side effects, such as trouble sleeping or loss of appetite.

Cognitive behavior therapy, or CBT, is another type of treatment. It involves talking with a professional to learn about ADHD and ways to manage it. CBT is commonly paired with medication, though it also can be used alone. CBT helps people with ADHD identify things they struggle with and ways to manage them.

Strategies for success

Each person with ADHD may find different strategies that help them succeed. For example, someone might divide a task into chunks to keep their attention from wandering. For struggles with time management, alarms and calendars can help someone keep track of their schedule.

Students with ADHD can request accommodations to help them at school. These might include a note-taker in class or extra time to complete tests or homework.

For Caliendo, online study tools and songs about the topics she was studying helped her memorize difficult content. A homework buddy helped her avoid procrastinating and made studying more fun. Caliendo also learned to not be shy about emailing her teachers for help.

“I do still struggle with concentration and organization,” Caliendo wrote in her Attention story. “[But] these days, I’m finding that I celebrate my successes way more than fixating on my challenges.”

There are also many resources that suggest tips for people with ADHD. For instance, How to ADHD is a YouTube channel highlighting ways to succeed with ADHD. It’s hosted by Jessica McCabe, an actress and writer who also has ADHD.

People with ADHD can become very successful, with or without medication. Many celebrities have been open about having ADHD. These include director Greta Gerwig, actor Tom Holland and Olympic gymnast Simone Biles. Caliendo, meanwhile, became a straight A student and an ambassador for her high school.

“Now that I look back, I recognize that there was — and is — nothing wrong with me,” wrote Caliendo. “I want to make sure everyone knows that ADHD is very common and that you are not alone.”