The spectrum of neurodevelopmental disorders: comorbidities as clues to pathogenesis.

This review looks at how different developmental conditions like autism, ADHD, and anxiety often occur together. Researchers found that these conditions share similar brain circuit problems in four main areas: thinking flexibility, sensory processing, repetitive behaviors, and emotional regulation. Brain scans show these problems can start as early as 18 months old. Importantly, treatments that target these specific brain circuits help across different conditions, suggesting we should focus on underlying brain mechanisms rather than just diagnostic labels.

This 2026 review synthesizes neuroimaging evidence from 2024-2025 examining how comorbidity patterns across neurodevelopmental disorders reveal shared brain circuit dysfunctions. The research identifies four core transdiagnostic dimensions (cognitive rigidity, sensory processing, repetitive behaviours, and social-emotional regulation) that show both convergent and disorder-specific patterns across autism, ADHD, OCD, Tourette syndrome, and anxiety disorders. Key findings include that temporal network inflexibility predicts symptom severity better than static connectivity measures, circuit dysfunction emerges as early as 18 months for sensory processing, and interventions targeting specific brain circuits produce improvements across diagnostic categories. The evidence supports dimensional models over categorical diagnoses for understanding neurodevelopmental conditions.

Findings support dimensional assessment approaches targeting core brain circuit functions rather than traditional categorical diagnoses. Early intervention focusing on sensory processing from 18 months may prevent developmental cascades. Circuit-based interventions may be more effective than disorder-specific treatments. Dynamic brain network assessment may improve clinical prediction and monitoring.

This is a review paper synthesizing existing research rather than presenting new empirical data. The review focuses specifically on neuroimaging studies from 2024-2025, which may limit the scope of evidence considered. Sample sizes and methodological details of the reviewed studies are not provided in the abstract.

High comorbidity rates across neurodevelopmental disorders (NDDs) may suggest shared pathogenic mechanisms rather than independent disease processes. This review synthesizes recent neuroimaging evidence (2024-2025) examining how comorbidity patterns reveal circuit-level convergence across traditional diagnostic boundaries. Studies of brain connectivity demonstrate that four core transdiagnostic dimensions of cognitive rigidity, sensory processing, repetitive behaviours, and social-emotional regulation show both circuit convergence and disorder-specific patterns across autism spectrum disorder, attention deficit hyperactivity disorder, obsessive compulsive disorder, Tourette syndrome and anxiety disorders. Analyses of how brain networks change over time clarify inconsistencies in earlier static studies, revealing that temporal network inflexibility predicts symptom severity better than anatomical connectivity alone.

Developmental studies suggest circuit dysfunction emerges early (as early as 18 months for sensory processing) and creates cascade effects throughout maturation. Interventions targeting specific brain circuits produce transdiagnostic improvements, validating circuit-based approaches over disorder-specific supports. Comorbidity patterns provide critical clues to shared pathogenesis, with circuit-level evidence supporting dimensional models over categorical diagnoses. The timing and of circuit dysfunction inform whether patterns reflect shared vulnerabilities, developmental cascades, or independent processes converging on similar phenotypes.

These findings suggest that assessments and interventions targeting underlying brain mechanisms may be more effective than traditional categorical diagnosis-based interventions.