Brain Imaging Study Reveals Three Distinct ADHD Subtypes

ADHD is diagnosed as a single disorder. But in exam rooms, it rarely looks that simple. Some patients struggle primarily with focus. Others can’t sit still. Still others wrestle with explosive emotions layered onto both. For patients and clinicians alike, that can mean a treatment process that includes trial and error and, at times, frustration, until the right medication is found.

Now, a new brain imaging study, released in late February, suggests that variability may not be random. Researchers from China, the United States, and Australia analyzed scans from 446 children with ADHD. By examining the gray matter—neuron-packed brain tissue essential for information transmission—the team identified three distinct subtypes, each with its own chemical interactions. The findings raise a provocative possibility: ADHD may not be one disorder expressed differently, but an umbrella for several related conditions with different neural signatures.

“Some of what this study has shown is what we clinically do anyway…trying to match the symptoms to the actual most effective treatments that we know,” says Melissa P. DelBello, a child psychiatrist at the University of Cincinnati College of Medicine and a researcher on the project. “But it’s really nice to have the data to show that our clinical impressions based on years of treating these patients have some biological validity to it.”

Although the researchers didn’t go in searching for predetermined subsets, the “biotypes” ended up mirroring what clinicians already often see in patients, says DelBello. Here’s what they found.

The first biotype was characterized by brain circuits involved in emotional regulation, including the prefrontal cortex—which is important for self-control and weighing consequences—and the pallidum, which “filters impulses before they become behavior,” says Manpreet K. Singh, co-author of the study and child psychiatrist at University of California Davis Health.

It’s an “overloaded control center,” Singh says. “Emotional and impulse control systems are overwhelmed, and very often the kids show more severe symptoms and more persistent emotional struggles,” she says. “So this is the very classic ADHD inattention and hyperactivity pattern.”

Clinically, this group most closely resembles what many people think of as “classic” ADHD—but amplified. Compared with the control group, these children showed the greatest divergence in brain connectivity. They scored high on both inattentiveness and impulsivity, along with pronounced emotional dysregulation, says Steven Pliszka, a psychiatrist at the University of Texas Health Science Center at San Antonio who was not involved in the study.

“That’s severe mood lability, temper tantrums, aggression,” he adds. “That is the group of ADHD kids who are most at risk for developing future psychiatric problems, depression, anxiety, bipolar disorder, substance abuse, and criminality. It’s an indicator of possible big issues later on.” Researchers posit that this group requires the earliest clinical interventions of the three.

The second biotype was marked less by inattention and more by difficulty regulating impulses. “You might describe this as an impulse circuit jam,” says Singh of brain connections characteristic of biotype 2. “People struggle to brake on impulses, and it's like the accelerator is strong, the brake timing is slightly off, and traffic flows fast, but unpredictably. You see more hyperactivity and impulsivity.”

Children in this group showed lower levels of inattentiveness than the other subtypes but greater disruption in circuits that regulate inhibition. Connectivity differences were strongest between the anterior cingulate cortex—a region that helps monitor errors and apply behavioral “brakes”—and an impulse-specific circuit of the pallidum.

When those regions fall out of sync, inhibitory control weakens. The result is less about wandering attention and more about difficulty suppressing impulses. Clinically, that pattern shows up as restlessness, blurting out answers, interrupting, or acting before thinking—behaviors rooted in a misfiring control system rather than an inability to focus.

Researchers traced the third biotype to disruptions in the superior frontal gyrus, a region that supports working memory and sustained attention. “Everything else seems to work, but focus drifts,” Singh says. Children in this group primarily showed inattention rather than hyperactivity.

Clinically, this presentation is often subtler—and more likely to be overlooked. It is also seen more frequently in girls, says Pliszka, who notes that because these children are less disruptive, they may struggle academically for years before coming to clinical attention.

This isn’t the first time researchers have attempted to sort ADHD into subgroups. Earlier editions of the Diagnostic and Statistical Manual of Mental Disorders listed three “subtypes,” now referred to as “presentations” to reflect how symptoms shift and overlap over time.

“There's no perfect prediction algorithm for ADHD,” explains Stephen Faraone, a psychologist at SUNY Upstate Medical University who was not involved in the study. “I've never seen one.”

Increasingly, researchers view ADHD not as a single, discrete disorder but as a dimension of traits distributed across the population. “People with ADHD are the extreme of a dimension … because it’s continuous,” comparing it to conditions like hypertension, where risk rises along a measurable spectrum rather than appearing as an all-or-nothing diagnosis.

The study’s authors stress that their identified “biotypes” are not new diagnostic categories. The findings will need replication, and ADHD remains a clinical diagnosis based on behavioral evaluation—not brain scans.

“Parents are often left being like, ‘What is that? Aren’t you going to do some tests?’ But that's the legitimate approach right now,” Pliszka says.

However, if the patterns hold up, researchers hope they could eventually help clinicians better match patients to medications—reducing the trial-and-error process many families experience.

Whether brain scans ever enter the diagnostic toolkit, it validates the diversity and intricacy of ADHD, researchers say. “What I hope this article does is signal to people it's more complicated than just calling it ADHD,” Singh says. “It's become a household name of how we explain our lives and our experiences, but it may be much more complicated than that.”