Sensory Issues and ADHD

Corbo, D., & Grandi, L. C. (2025). Neurobiological Convergence in SPDs and ADHD: Insights from a Narrative Review. Preprints.org. https://doi.org/10.20944/preprints202510.1195.v1

🧠 What the Study Is About

This review looks at how Sensory Processing Disorders (SPDs) and Attention-Deficit/Hyperactivity Disorder (ADHD) might overlap in the brain — and where they differ.

Both conditions can look similar behaviorally (distractibility, fidgeting, emotional outbursts), but the brain mechanisms behind them aren’t exactly the same. The study’s goal is to help researchers and clinicians tell them apart and develop better tools for diagnosis and treatment.

👀 Why This Matters

• SPDs are often mistaken for ADHD, especially in young children.
• Misdiagnosis can lead to the wrong treatment — for example, using ADHD medication for a child whose main issue is sensory regulation.
• The review argues that understanding the neurobiological (brain-based) differences can help develop specific biomarkers — measurable signs in the brain that clarify what’s really going on.

⚙️ Key Brain Insights

1. Shared Brain Networks

• Both ADHD and SPD involve fronto-striatal circuits, which control attention, reward, and emotion.
• These include areas like the prefrontal cortex, striatum, and thalamus.
• The amygdala (emotion processing) and insula (feeling states and social touch) are active in both conditions.
• In ADHD, these areas often show over- or under-activation linked to emotional impulsivity or poor sensory filtering.
• In SPD, they seem to be related to over-responsivity to sensory input (e.g., sounds, textures).

2. Different Core Mechanisms

• ADHD mainly involves dopamine and norepinephrine systems, affecting motivation and attention.
• SPD seems more tied to sensory integration pathways (especially thalamocortical circuits) and glutamate/GABA balance, which affects how the brain filters and combines sensory input.

3. Brain Waves and Electrical Activity

• EEG studies show that children with ADHD and SPD both have unusual brain oscillations, especially in:
• Theta waves (4–8 Hz) – linked to attention and focus.
• Alpha waves (8–13 Hz) – linked to calm alertness.
• Mu rhythm (sensorimotor activity) – linked to body awareness and movement control.
• These differences may explain restlessness, distractibility, and sensory overload.

4. Structural Brain Differences

• ADHD brains often have:
• Smaller volumes in the frontal lobes, cerebellum, and basal ganglia.
• Delayed cortical maturation, especially in the prefrontal cortex (responsible for planning and attention).
• SPD brains show:
• Disrupted white matter connections (the brain’s communication “highways”) between sensory and motor areas.
• Especially affected are the corpus callosum and internal capsule, which integrate sensory signals.

🔬 What This Means for Diagnosis and Therapy

• Sensory issues should be assessed routinely in ADHD evaluations.

Many children with ADHD also have sensory processing challenges, but they are often overlooked.

• Biomarkers (like EEG or fMRI patterns) could eventually help distinguish ADHD from SPD — leading to more personalized interventions.
• Integrated therapies combining attention training, sensory integration, and emotional regulation might be most effective for those with overlapping features.

💡 Big Picture Takeaways

🧩 Conclusion

SPDs and ADHD share some brain patterns — especially in areas that regulate attention, emotion, and sensory responses — but they’re not the same condition.

Understanding how they overlap can prevent misdiagnosis and lead to better, more personalized treatment.

Future research combining brain imaging, EEG, and behavioral data could uncover clear biological markers for each disorder.