Brain criticality variability explains why ADHD symptoms differ across individuals

A new study published in Translational Psychiatry suggests that differences in how an individual brain organizes itself at the edge of stability—often called “brain criticality”—may help explain why attention deficit/hyperactivity disorder (ADHD) symptoms vary so widely across the population. Rather than treating ADHD traits as a single, uniform outcome, the research points to a continuous spectrum shaped by underlying neural dynamics.

Brain criticality describes a state where neural activity hovers near a transition between orderly and disordered behavior. In that regime, the brain can balance flexibility and stability, enabling rapid adaptation while avoiding runaway excitation or overly rigid signaling. The authors propose that individuals may differ in how closely their brain dynamics align with this critical operating point.

To test the idea, the team combined large-scale behavioral assessments with neuroimaging-derived measures of brain dynamics. They then evaluated whether signatures consistent with criticality—such as scaling behaviors and temporal organization of neural activity—track with ADHD symptom severity. The key claim is that variability in these criticality-related markers parallels symptom differences across people.

The findings imply that ADHD symptoms could reflect altered “tuning” of the brain’s dynamical regime. If the brain operates slightly away from criticality, information processing may become less optimal, potentially affecting attention control, impulse regulation, and the ability to sustain goal-directed behavior. Importantly, the study frames the effect as probabilistic and dimensional rather than categorical.

Critically, the work emphasizes that brain criticality is not merely a theoretical abstraction. The authors link it to measurable features of functional brain activity and demonstrate that these features can account for variation in symptom expression even when accounting for individual differences in overall neural activity.

While the study does not yet establish causality, it introduces a mechanistic bridge between network-level dynamics and clinical heterogeneity. That bridge could guide next-generation models of ADHD that predict symptom patterns from dynamical properties rather than only from static biomarkers.

If validated in independent cohorts and with longitudinal data, the criticality framework may open new routes for intervention. For example, computational targeting of dynamical regimes—via neurostimulation paradigms designed to shift network organization—could eventually be explored as a precision strategy.

For now, the research positions brain criticality as a unifying concept for why ADHD symptoms spread across the population in a graded, individualized way. The DOI is: 10.1038/s41398-026-04267-0.