Brain Scan Study Suggests ADHD May Actually Exist in Three Different Forms

For decades, attention-deficit/hyperactivity disorder (ADHD) has been treated as a single diagnosis built around a checklist of behavioral symptoms. Doctors look for patterns of inattention, impulsivity, or hyperactivity and if those symptoms are present for long enough, the person receives the ADHD label. Yet anyone who has spent time around people with ADHD knows that the experience can look very different from one individual to another. One child may struggle to stay focused during lessons while another constantly feels restless and unable to slow down. Even adults who share the diagnosis often describe completely different daily challenges. This inconsistency has led many scientists to question whether ADHD is truly one condition or a group of related conditions that simply share overlapping symptoms.

New research is now adding weight to that idea. Scientists studying brain scans from more than a thousand participants have discovered evidence suggesting that ADHD may actually exist in several biologically different forms. Instead of relying only on behavioral descriptions, the research examined patterns inside the brain itself and found three distinct ADHD biotypes. These groups showed different brain network patterns, genetic signals, and potential treatment responses. The findings do not mean the current diagnosis is wrong, but they suggest the picture is more complex than previously believed. Understanding that complexity could eventually reshape how ADHD is diagnosed and treated in both children and adults.

Why ADHD Has Always Been Difficult to Define

ADHD is considered one of the most common neurodevelopmental conditions, yet it has always been unusually difficult to define in a precise way. Two individuals can receive the same diagnosis while experiencing entirely different symptoms. Some struggle mainly with attention and concentration. Others experience constant physical restlessness. Still others deal with impulsive behavior that affects decision making and relationships. Because the experiences vary so widely, many researchers describe ADHD as a heterogeneous condition rather than a uniform disorder.

The current diagnostic system used by clinicians comes from the Diagnostic and Statistical Manual of Mental Disorders, commonly known as the DSM-5. This system focuses on observable behaviors such as difficulty sustaining attention, forgetfulness, excessive movement, or interrupting others during conversations. While these criteria help doctors identify patterns, they do not necessarily explain what is happening inside the brain. Two people might meet the same checklist criteria even though their neurological profiles are very different.

Researchers behind the recent brain imaging study argue that this limitation may be holding back progress in understanding ADHD. As they explained, “The current diagnostic framework assigns a single diagnostic label to what is fundamentally a heterogeneous syndrome that likely arises from diverse neural mechanisms.” In other words, ADHD may appear similar on the surface but develop through different biological pathways in the brain.

This growing recognition has encouraged scientists to search for biological markers that might help explain the wide variety of ADHD experiences. Instead of grouping everyone together under a single behavioral label, researchers are beginning to explore whether distinct brain patterns could reveal different types of ADHD.

The Brain-Scan Study That Changed the Conversation

The research that sparked this discussion was conducted at West China Hospital at Sichuan University. Instead of relying only on symptom reports or behavioral assessments, the team decided to examine the physical structure of the brain using MRI scans. Their dataset included more than 1,150 participants, allowing the researchers to look for patterns that might not be visible in smaller studies.

Rather than analyzing a single brain region at a time, the scientists focused on how different parts of the brain connect with one another. They used a method known as morphometric similarity networks, which compares structural traits such as thickness and volume across brain regions. This technique helps researchers understand how brain areas share physical characteristics and how those patterns differ between individuals.

The team also applied a statistical framework called normative modeling. This approach works somewhat like a developmental growth chart. Just as pediatricians compare a child’s height and weight to typical ranges for their age, normative modeling compares an individual’s brain features to population expectations. The goal is to identify where brain development diverges from typical patterns.

After mapping these brain networks, the researchers used an artificial intelligence clustering algorithm known as HYDRA to group participants based on their neurological differences. The results revealed three distinct ADHD biotypes, each with unique brain structures and clinical characteristics. The authors summarized the discovery clearly, writing: “We identified three distinct topology-derived biotypes, each characterized by unique clinical-neural profiles, longitudinal trajectories, and spatial molecular signatures.”

The Three ADHD Brain Types Researchers Identified

The study divided ADHD into three biological categories based on how brain networks differed from neurotypical patterns. Each group showed a unique neurological profile and different levels of symptom severity. These differences suggest that ADHD may not represent a single pathway in the brain but several related ones.

The first group showed widespread structural differences across many brain networks. Children in this category tended to display the most severe ADHD symptoms. The study also found that these individuals were more likely to continue experiencing symptoms as they grew older. Because the brain changes appeared across many regions, this group may represent the most neurologically complex form of ADHD.

The second group showed more localized differences, particularly in deep brain areas known as subcortical regions. These structures play an important role in motivation, reward processing, and emotional regulation. Individuals in this group generally displayed moderate symptom severity. Their brain patterns suggested a more focused neurological variation compared with the broader changes seen in the first group.

The third group showed minimal structural differences in the brain compared with neurotypical individuals. Despite this, participants still displayed behavioral symptoms consistent with ADHD. Their cognitive profiles looked similar to those of people without ADHD in several areas, suggesting that subtle functional differences rather than large structural changes may drive their symptoms.

Why This Discovery Could Change ADHD Treatment

One of the most significant findings from the study was that these brain types appeared to be connected to different biological markers. Researchers examined gene expression patterns and neurotransmitter maps and found links between the ADHD groups and brain chemicals such as dopamine and serotonin. These chemicals are already known to play a role in attention and motivation.

The study also suggested that each biotype may respond differently to medication. Stimulant medications are currently one of the most common treatments for ADHD, but their effectiveness varies widely between individuals. Some patients experience dramatic improvements, while others see little benefit or struggle with side effects.

If these biological subtypes continue to be confirmed in future studies, doctors may eventually use brain imaging to help guide treatment decisions. Instead of testing medications through trial and error, clinicians might one day match treatments to a patient’s neurological profile.

This approach is part of a broader movement known as precision psychiatry. The goal is to move away from one-size-fits-all treatment models and instead design interventions based on the unique biology of each patient.

ADHD and Autism Often Overlap

Another reason ADHD can be difficult to study is that it frequently overlaps with other neurodevelopmental conditions, particularly autism spectrum disorder. Research suggests that between 20 percent and 37 percent of autistic individuals also experience ADHD symptoms. This overlap can make diagnosis complicated because both conditions can affect attention, emotional regulation, and social interactions.

Autism is typically defined by differences in social communication along with restricted or repetitive patterns of behavior. Individuals may struggle to interpret body language, tone of voice, or sarcasm. Many also experience sensory sensitivities and a strong preference for predictable routines. These characteristics reflect differences in how the brain processes social and environmental information.

ADHD, in contrast, is primarily characterized by inattention, hyperactivity, and impulsivity. Someone with ADHD might struggle to stay focused on tasks, frequently lose track of time, or make quick decisions without considering the consequences. These symptoms often stem from differences in executive functioning, which is the brain’s ability to plan, organize, and regulate behavior.

Because the two conditions can appear similar in certain situations, professionals often need detailed assessments to determine whether a person is experiencing ADHD, autism, or both. Accurate diagnosis is important because the support strategies and therapies used for each condition can differ.

Why Many Adults Discover ADHD Later in Life

For many people, ADHD is not recognized until adulthood. Historically, most research focused on children, which meant that adults who struggled with attention or impulsivity were often overlooked. Many developed coping strategies that helped them manage school or work responsibilities, even though underlying difficulties remained.

Adult ADHD often looks different from childhood ADHD. Instead of obvious hyperactive behavior, many adults describe an internal sense of restlessness. They may feel constantly mentally busy, struggle to complete long tasks, or find it difficult to stay organized. These challenges can affect careers, finances, and relationships.

Women in particular are frequently diagnosed later in life. Their symptoms often appear as quiet inattention or internal anxiety rather than disruptive behavior, which historically shaped ADHD stereotypes. As a result, many women spend years believing their struggles are personal failures rather than neurological differences.

Receiving a diagnosis later in life can be a turning point. For many adults, understanding that ADHD is a neurodevelopmental condition rather than a character flaw provides clarity and opens the door to treatment, coaching, and supportive strategies.

A New Way of Understanding ADHD

The discovery of potential ADHD brain types represents an early step toward a deeper understanding of the condition. While the research does not change the current diagnostic system overnight, it highlights the complexity of how attention and behavior are regulated in the brain. Scientists now recognize that the label ADHD may describe several related neurological patterns rather than one uniform disorder.

Future research will need to follow participants over many years to see whether these brain categories remain stable over time. Long-term studies could reveal whether the biotypes continue into adulthood and whether they predict treatment outcomes or life experiences.

If the findings continue to hold up, brain imaging could eventually become part of ADHD evaluation in the future. Such tools might help identify which individuals are at higher risk of persistent symptoms and which treatments may work best for them.

For families and individuals living with ADHD, the research offers an important reminder. Differences in attention, focus, and behavior do not come from a single source. The human brain is complex, and the diversity seen in ADHD may reflect that complexity rather than a single disorder. Recognizing these differences could lead to more personalized support and better outcomes for millions of people worldwide.

Sources:

1. Pan, N., Long, Y., Qin, K., Pope, I. Z., Chen, Q., Zhu, Z., Cao, Y., Li, L., Singh, M. K., McNamara, R. K., DelBello, M. P., Chen, Y., Fornito, A., & Gong, Q. (2026). Mapping ADHD heterogeneity and biotypes by topological deviations in morphometric similarity networks. JAMA Psychiatry. https://doi.org/10.1001/jamapsychiatry.2026.0001
2. Attention-Deficit/Hyperactivity Disorder (ADHD). (n.d.). National Institute of Mental Health (NIMH). https://www.nimh.nih.gov/health/topics/attention-deficit-hyperactivity-disorder-adhd
3. Attention-Deficit / hyperactivity Disorder (ADHD). (2024, October 11). Attention-Deficit / Hyperactivity Disorder (ADHD). https://www.cdc.gov/adhd