the vitious cycle of fear and its relation to somatic disease

So here is a little neurobiology tidbit I stumbled upon while watching the psychiatry lectures...

The Key Players

A foundational idea to the (patho-)physiology of anxiety is the neuronal circuit described by LeDoux (1994), which looks like this:

The Amygdala in turn activates the Hypothalamus, which results in a vegetative response.

The Vitious Cycle

In panic disorder it has been shown that CRH induces the activation of a region of the brain stem referred to as the Locus coeruleus.[^1]

It has also been shown that deprivation of carbon-dioxide ("hypocapnia") activates the Locus coeruleus as well. It is a part of the reticular formation, noticable due to its dark coloration, resulting from a production neuromelanin. It produces 95% of CNS norepinephrine and mediates a sympathoadrenergic response.

The Relationship

What caught my eye was that there are certain somatic diseases that are related to a very profound fear of death. Specifically, pulmonary embolism, heart attack, and asthma attack. What is characteristic for these diseases is the fact that they are related to hypoxia. As a compensation, patients hyperventilate, which leads to hypocapnia. Might hypocapnia resulting from hyperventilation in acute cardiopulmonary disease result in a profound fear response?

Honestly, I don't know, but it is a thought I want to explore at some point, when I'm out of exam-prep-hell lol, so here is a digital brainfart to remind me of this.

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citations:
[^1]: Tüscher et al. 2014

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