What Exactly Is ADHD?

By Demi Guo

Although officially recognized nearly 40 years ago, attention-deficit/hyperactivity disorder

(ADHD) has been gaining more attention lately due to a growing awareness of its symptoms.

Diagnoses of attention deficit hyperactivity disorder (ADHD) have risen in recent years, driven in

part by our growing awareness of its symptoms. Understanding of the disorder evolved

significantly in 1987, when the American Psychiatric Association’s Diagnostic and Statistical

Manual of Mental Disorders, revised third edition (DSM-3), formally consolidated attention deficit

and hyperactivity symptoms into the diagnosis of ADHD. But what is it really?

According to the National Institute of Mental Health, ADHD is a neurodevelopmental disorder

that includes the following types of symptoms: difficulty paying attention, staying on task, or

being organized; hyperactivity, such as restlessness or talking excessively; and impulsivity,

such as interrupting others or having trouble waiting one’s turn. While anyone may sometimes

display these behaviors, having ADHD means that a person with the disorder often exhibits

these actions across multiple situations, such as school, home, or work.

ADHD is one of the most common disorders diagnosed in children, manifesting in behaviors

such as frequent daydreaming during class or the inability to complete homework. “All of us can

pay attention when something is novel or interesting,” says Harold Koplewicz, senior child and

adolescent psychiatrist at the Child Mind Institute. “It’s when it gets challenging and boring that

we have to literally release chemicals in our brain to be able to focus and to pay attention.”

Neuroimaging studies suggest certain brain regions, especially the frontal lobe (located behind

the forehead), may develop more slowly in children with ADHD compared to their peers. This

lobe controls multiple processes, including attention and decision-making. Although these

structures still do develop over time, they tend to mature at a slower pace.

The Challenge of Being Patient

The brain comprises different networks that maintain focus, plan tasks, and perceive rewards for

completing those tasks. Neurons, which carry messages within each network, function

differently in people with ADHD. Those with the disorder may find it easier to complete a task if

there are immediate results, while tasks with multiple steps and delayed gratification may pose

a challenge.

This can cause individuals with the condition to become impatient and impulsive in their rush to

complete tasks. “As children, they leap into action without thinking of the consequences. As

adults, they drive too fast, use power tools carelessly, and plunge into activities without thinking

of the danger,” stated a 2008 Dove Medical Press study.

As they mature, most people can understand the connection between their actions and the

effects they may have. “Most teenagers realize that, if I go into a car, I better put a seat belt on

because there’s a chance the car will stop short and I’ll bump my head on the divider,”

Koplewicz says. “Maybe those connections are not as strong even in adults who have ADHD,

even though their frontal lobe is as big as it’s going to be.”

A Cycle of Extremes

Neurotransmitters—chemicals that serve as messengers that send signals throughout the

body—also come into play. Two major neurotransmitters include dopamine and norepinephrine.

People with ADHD use up these chemicals more quickly, depleting the reserves meant to help

them stay focused.

This can result in an all-or-nothing mentality—cycling between inattention and episodes of

intense focus, sometimes referred to as hyperfixation. Although not an official diagnostic term,

hyperfixation is widely reported by people with ADHD and discussed in grassroots advocacy

and emerging literature.

People with ADHD use up dopamine and norepinephrine faster, depleting the reserves meant to

help them stay focused.

The term “hyperactive” in ADHD’s name leads many to associate the disorder with restlessness.

However, the opposite can also be true—behaviors such as daydreaming or seeming

unattached to one’s surroundings. “You kind of latch onto those things that you find really

interesting [hyperfixations], and because you’re giving all your attention to those, it can pull you

away from other responsibilities,” says Dustin Chandler, a 45-year-old parent diagnosed in his

20s.

Chandler is a prime example of another recently recognized facet of ADHD—it is not solely a

childhood disorder. It has been diagnosed in about one out of nine U.S. children ages three to

17, with the historical assumption that symptoms diminish with age. However, recent research

indicates that many people continue to experience symptoms long after childhood.

Evolving Faces of the Disorder

Cultural background and upbringing can influence how ADHD manifests across various

demographics. Take, for example, the rise in diagnoses in people assigned female at birth in the

short period between 2020 and 2022. This change challenges the now-outdated notion that

ADHD is primarily a “boy disorder.” Girls and women frequently display symptoms of the

inattentive type, like daydreaming and forgetfulness, rather than the hyperactive or impulsive

type, which are more common in those assigned male at birth.

Part of the reason for the shift could be that people are becoming aware of the many ways

ADHD can show up and how often it presents with comorbidity like anxiety or autism. These

disorders can overlap significantly, which may contribute to diagnostic confusion or delays.

Many children grow into adulthood without ever being aware they have ADHD, according to

Koplewicz.

More research is needed on the ways ADHD presents, as Myles Moody, an assistant professor

of sociology at the University of Alabama, points out. Studies show that white children are more

likely to be diagnosed with ADHD. At the same time, other racial groups may be

underdiagnosed because of factors that include access to resources and social stigma.

“ADHD over a lifespan can look very, very different,” Koplewicz says. As awareness of ADHD

grows, experts are recognizing the different ways the disorder manifests in people, whether

driven by cultural, social, environmental, or scientific factors.