Recent research has identified three unique types of ADHD, a discovery that could transform the diagnosis and treatment for countless Americans.

ADHD, or attention-deficit/hyperactivity disorder, is a neurodevelopmental condition impacting focus, impulse regulation, and energy levels.

According to the CDC, approximately one in ten children in the United States have been diagnosed with ADHD, affecting around 7 million young individuals, while an estimated 15 to 17 million adults also live with it.

Traditionally, ADHD has been viewed as a single disorder, yet it presents a wide array of symptoms. Some individuals may have difficulty concentrating on tasks, while others experience intense emotional reactions.

Because symptoms can vary greatly between individuals, similar to autism, identifying the most effective combination of medication, therapy, and other treatments can often involve lengthy periods of trial and error.

However, a team of researchers from the United States, China, and Australia propose that ADHD might actually be classified into distinct categories.

The international team took MRI scans of nearly 500 children diagnosed with ADHD and compared them to about 700 children without the condition. These scans showed structural and functional differences in the brain, such as reduced blood flow and smaller areas, that could lead to symptoms.

By examining brain gray matter – tissue containing neurons that help the brain transmit information – researchers identified three subgroups: severe-combined type with emotional dysregulation (biotype 1); predominantly hyperactive and impulsive (biotype 2); and predominantly inattentive (biotype 3). 

A new study has broken ADHD up into three distinct groups, which could improve treatments for thousands (stock image)

Biotype 1 is defined by more severe symptoms and emotional outbursts, while biotype 2 most commonly results in hyperactivity and impulsive behavior. Biotype 3, meanwhile, is marked mostly by inattention or a drift in focus, which may be more subtle than the other types.

Doctors who were not involved in the research said the findings may pave the way for better ADHD diagnostics and more effective treatments.

‘This study is interesting because it reinforces something clinicians have long suspected: ADHD isn’t a single, uniform condition,’ Jonathan Alpert, a psychotherapist in New York City and Washington DC, who was not involved in the study, told the Daily Mail. 

‘What we call ADHD likely includes several different patterns of attention, impulse control and emotional regulation. Two people can receive the same diagnosis but have very different underlying challenges.’  

The study, published in the journal JAMA Psychiatry, collected patient data from West China Hospital of Sichuan University, University of Cincinnati, Kennedy Krieger Institute in Baltimore, NYU Langone Medical Center in New York City, Oregon Health & Science University and Peking University Institute of Mental Health in China.

Children included were between six and 18 years old with an average age of 11. There were 446 children who were formally diagnosed with ADHD and 708 neurotypical controls. Of them, 142 children were biotype 1, 177 came under biotype 2, and 127 were biotype 3.

All participants underwent MRI scans, allowing researchers to measure gray matter levels in areas of the brain, including the prefrontal cortex – responsible for executive function – the anterior cingulate cortex – involved in cognition and emotion – and the superior frontal gyrus –  a region that supports working memory and attention.

The above graph shows the number of children in each biotype and how the biotypes lined up with symptoms. The width of each flow represents the number of participants 

The above group shows the rates of hyperactivity/impulsivity and inattention broken up by ADHD biotype

Biotype 1 was characterized by brain circuits in the prefrontal cortex, which manages self-control, weighing consequences and emotional regulation, and the pallidum, an area that regulates motivation and reward. 

In this group, classic ADHD signs such as inattention and emotional outbursts tend to be more severe and at a greater risk of tantrums and aggression, the team noted.

In biotype 2, patients have increased hyperactivity and impulsivity, which the study suggests could be due to impairments in the anterior cingulate cortex, and an impulse-specific circuit in the pallidum.

The team noted people in biotype 2 may experience more restlessness, blurting out answers, interrupting or acting before thinking.

People in biotype 3 experience inattentiveness, which the study shows may be due to disruptions in the frontal gyrus. This appears more subtle than the other two biotypes, which may cause it to be more overlooked. 

The team also suggested it may be more common in girls, who are largely underdiagnosed. 

‘Girls and many adults with ADHD often present with the more inattentive and less disruptive patterns, which are easier to overlook in classrooms or workplaces,’ Dr Lori Bohn, a psychiatric-mental health nurse practitioner and medical director at Voyager Recovery Center in California, who was not involved in the study, told the Daily Mail.

She added: ‘If clinicians and researchers become more aware that some ADHD presentations are subtle and neurologically distinct, it could encourage more careful screening and reduce the tendency to equate ADHD only with hyperactive behavior. 

‘In that sense, identifying subtypes could help broaden our understanding of who ADHD affects and how it shows up across different populations.’

Experts not involved with the research are hopeful the findings could lead to more personalized treatments than standard drugs such as Adderall.  

The study found biotype 3 is more common in girls, who are often underdiagnosed with ADHD due to having more subtle symptoms. 

‘Finding subtypes could help clinicians tailor treatment more effectively. A child whose primary difficulty is emotional regulation may need a very different approach from someone whose main challenge is sustained attention. In theory, a more precise understanding of ADHD could improve care,’ Alpert said.

‘In the future, this could help more people get diagnosed with ADHD, such as overlooked populations, like girls and adults. But, there is no use in diagnosing someone unless you have more refined treatments,’ Dr Carole Lieberman, a board-certified psychiatrist in Beverly Hills, who was not involved in the study, told the Daily Mail.

However, relying on brain scans also has its limitations, Alpert notes. ‘We’re not at the point where a doctor can scan a child’s brain and determine their ADHD subtype,’ he said. ‘Most diagnoses still rely on behavioral observations and reports from parents and teachers.’

Alpert added: ‘Attention problems are heavily influenced by environmental factors – sleep deprivation, constant digital stimulation, school demands and stress – which brain scans can’t capture.’

Bohn also noted because the study consisted of children, ‘we don’t yet know whether the same brain-based subtypes would appear in adults or how these patterns might change over time.’

Brain scans can also run into the thousands of dollars, even with insurance, and can be difficult for psychiatrists and psychologists to interpret. 

‘Clinicians do not have readily accessible brain imaging facilities and experts who can distinguish between these subtypes, whereas psychiatrists can distinguish the symptoms and the likely trajectory of the disorder,’ Lieberman said.

While the study could lead to more focused ADHD treatments, there is still much to learn.

‘The challenge going forward is making sure new scientific insights lead to more thoughtful treatment – not simply more labels in a culture that is already quick to pathologize ordinary difficulties with focus and self-control,’ Alpert said.