Brain Scans Reveal 3 Distinct ADHD Subtypes

Research published on April 30, 2026, suggests that attention deficit hyperactivity disorder (ADHD) may be categorized into three distinct subtypes based on brain structure rather than clinical symptoms alone. The study used neuroimaging and semi-supervised learning to identify patterns of cortical thickness that differ significantly among adolescents with the condition.

The findings, based on data from 6,509 adolescents in the Adolescent Brain Cognitive Development (ABCD) study, indicate that ADHD is more heterogeneous than previously understood. While traditional diagnoses rely on observed traits, this data-driven approach identifies subtypes based on the physical development of the brain’s cortex.

Identifying the Three Subtypes

The researchers identified three specific subtypes characterized by their cortical thickness (CT) compared to a control group. These are categorized as the under-developed, over-developed, and mixed subtypes.

The under-developed subtype is marked by lower cortical thickness. According to the study, individuals in this group showed significantly lower cognitive scores and were associated with lower socioeconomic status.

The over-developed subtype is characterized by higher cortical thickness. This group demonstrated a distinct clinical profile, specifically regarding how they responded to medical intervention.

The mixed subtype exhibited a combination of these patterns, further highlighting the complexity of the disorder’s presentation across different individuals.

Impact on Treatment and Biology

A primary finding of the research is the variation in treatment efficacy across these subtypes. The study found that the over-developed subtype had the worst response to stimulant medication, which is a standard treatment for ADHD.

The researchers believe this difference in medication response is linked to the underlying neurobiology of each subtype. The study revealed significant differences in neurotransmitter distributions and gene expressions among the groups.

Specifically, the upregulation of dopamine and other excitatory pathways appeared to play a strong role in the under-developed and mixed subtypes. However, this upregulation was not present in the over-developed subtype, which may explain why stimulant medications—which typically target these pathways—were less effective for that group.

Moving Toward Personalized Therapy

The current clinical method of subtyping ADHD relies on traits that can be subject to clinician judgment and may lack reliability in predicting patient outcomes. By using neuroimaging, researchers aim to provide a more objective framework for diagnosis.

The study suggests that neuroimaging-based subtyping could uncover critical differences in clinical presentations, genetics, and neurobiology. This shift could allow healthcare providers to move away from a one-size-fits-all approach to ADHD treatment.

By identifying which subtype a patient falls into, clinicians may eventually be able to guide personalized therapy, selecting medications or interventions that align with the patient’s specific neural profile and neurotransmitter activity.

While these findings provide a new lens for understanding ADHD, the research emphasizes that neuroimaging is a tool to complement clinical diagnosis. Further validation is required to integrate these subtypes into standard medical practice.