The Sensitivity Threshold Model
The Sensitivity Threshold Model (STM) offers a fresh way of understanding mental health conditions like schizophrenia. Instead of focusing only on brain chemicals or genes, STM looks at how stress, sensory input, and individual sensitivity combine over time. It explains how people with heightened sensitivity can become overwhelmed when life’s demands exceed their brain’s natural limits, leading to mental health struggles. This framework helps make sense of how illness develops — and points to ways we can reduce overload, protect sensitive individuals, and support recovery in a more holistic way.
These are the Core Tenets of the STM Model to show the mechanism of illness progression in the Sensitivity Threshold Model (STM) Framework — from start to end.
Here’s how the STM explains mental illness progression visually.
Inherent Sensitivity
Some individuals are born with or develop heightened sensitivity (genetic, neurodevelopmental, or environmental origins)
Maya’s Experience:
“Even as a child, Maya was deeply affected by things others brushed off — bright lights made her wince, loud environments overwhelmed her, and she cried easily during emotionally charged scenes in movies. Her teachers called her gifted and sensitive. Her parents called her ‘dramatic.’ But Maya wasn’t weak — her nervous system was simply wired to register more input from the world around her.”
Chronic Stress and Input Load
Over time, these sensitive individuals face accumulating stressors — sensory bombardment (noise, light, social stress), emotional strain, toxins, poor diet, etc.
Maya’s Experience:
“In university, Maya tried to keep up with her peers — long hours, loud social events, little sleep. Add to that family pressure to excel, social anxiety, and a breakup in her second year. Her once-manageable sensitivity became harder to regulate. She felt overstimulated, exhausted, and began having trouble concentrating in lectures.”
Threshold Breach → Overload
When the total input exceeds the individual’s processing capacity, the brain begins to struggle
Maya’s Experience:
“One night during exam season, Maya stayed up late studying and began hearing a faint voice say her name. At first, she brushed it off. But the next day, the voice returned — louder, more insistent. Her thoughts began racing, and she couldn’t focus. She described the feeling as ‘my brain short-circuiting — like a fuse had blown and nothing made sense anymore.’”
Neurobiological Cascade
The overload triggers system responses:
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HPA axis stress → high cortisol
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Neurotransmitter shifts → dopamine, glutamate, serotonin imbalances
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Neuroinflammation and oxidative stress
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Sensory gating failure (poor filtering of stimuli)
Maya’s Experience:
“At the clinic, doctors noted Maya had elevated cortisol levels and abnormal sleep cycles. She was hyper-alert, paranoid, and emotionally raw. Medication helped blunt the worst symptoms, but no one could explain why it all happened so suddenly. To her, it felt like her body and mind had gone to war with each other — but the real trigger was months of silent overload.”
Symptom Emergence and Feedback Loop
Stress Symptoms Emerge. Each episode can further weaken the system, lowering the threshold for future overload and deepening the illness
Maya’s Experience:
“After hospitalization, Maya was told she had a lifelong brain disorder. But no one helped her understand why her brain had broken down. Without answers, she began to fear herself — every emotional reaction felt like a sign of relapse. This fear itself became a stressor. Her identity was now tied to illness, and the cycle threatened to repeat.”
