The brain distinguishes between threats primarily through the interaction between the amygdala and the prefrontal cortex. When you encounter a physical threat, such as a moving vehicle, the amygdala triggers an immediate fight or flight response. This sends rapid signals to the hypothalamus, causing an instant surge of adrenaline and cortisol to prepare your muscles for action.
In contrast, psychological threats like social anxiety or work deadlines are processed through a more complex cognitive loop. The prefrontal cortex, which handles higher order reasoning, evaluates the situation. It determines that while the thought is stressful, it does not pose a direct threat to your physical survival. If the prefrontal cortex can successfully regulate the amygdala, it can dampen the hormonal surge, preventing a full scale physiological stress response.
However, chronic psychological stress can overwhelm this regulation. When the brain repeatedly perceives mental stress as an existential threat, the prefrontal cortex loses some of its inhibitory control. This leads to prolonged cortisol exposure, which is why long term mental stress can cause physical symptoms similar to those experienced during a physical emergency.
