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Mental stress causes vasoconstriction in subjects with sickle cell disease and in normal controls, 2020, Payal Shah et al

Discussion in 'Other health news and research' started by Mij, Sep 12, 2022.

  1. Mij

    Mij Senior Member (Voting Rights)

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    Abstract
    Vaso-occlusive crisis (VOC) is a hallmark of sickle cell disease (SCD) and occurs when deoxygenated sickled red blood cells occlude the microvasculature. Any stimulus, such as mental stress, which decreases microvascular blood flow will increase the likelihood of red cell entrapment resulting in local vaso-occlusion and progression to VOC. Neurally mediated vasoconstriction might be the physiological link between crisis triggers and vaso-occlusion.

    In this study, we determined the effect of mental stress on microvascular blood flow and autonomic nervous system reactivity. Sickle cell patients and controls performed mentally stressful tasks, including a memory task, conflict test and pain anticipation test. Blood flow was measured using photoplethysmography, autonomic reactivity was derived from electrocardiography and perceived stress was measured by the State-Trait Anxiety Inventory questionnaire.

    Stress tasks induced a significant decrease in microvascular blood flow, parasympathetic withdrawal and sympathetic activation in all subjects. Of the various tests, pain anticipation caused the highest degree of vasoconstriction. The magnitude of vasoconstriction, sympathetic activation and perceived stress was greater during the Stroop conflict test than during the N-back memory test, indicating the relationship between magnitude of experimental stress and degree of regional vasoconstriction. Baseline anxiety had a significant effect on the vasoconstrictive response in sickle cell subjects but not in controls.

    In conclusion, mental stress caused vasoconstriction and autonomic nervous system reactivity in all subjects. Although the pattern of responses was not significantly different between the two groups, the consequences of vasoconstriction can be quite significant in SCD because of the resultant entrapment of sickle cells in the microvasculature. This suggests that mental stress can precipitate a VOC in SCD by causing neural-mediated vasoconstriction.

    https://www.haematologica.org/article/view/9478
     
  2. rvallee

    rvallee Senior Member (Voting Rights)

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    So by stress they mean exertion. It's the mental equivalent of using your muscles, there's an increased energy demand, met in part by cortisol. The energy is not free, there is no separate "mind" that can operate without the brain needing a fuel supply matching the energy demand.

    Which is fine. Can we just get accurate vocabulary, though? Stress is too commonly associated with worrying about doing something, never about actually having to do the thing. IMO this is why stress, in the general sense of having to dedicate more resources, is such an issue with us, why it causes PEM: because it IS exertion. But here they use some anxiety questionnaire for it, distorting what it actually means.

    There's no such thing as a free lunch and the brain is the most power-hungry organ in the body. Decades of pseudoscience have badly damaged the basic vocabulary here. It's so easy to make it all about personal worries and identity.

    But what this is all is energy from exertion. Mental energy uses much of the same fuel as the rest of the body, and will demand an increase in glucose just the same, that's where cortisol likely comes into play. This is where this whole mind-body thing is damaging, as if the "mind" can work endlessly without using any resources or fuel, or having to clean-up waste material.

    It's absurd to think of how much progress could be made by simply resetting everything back to fundamentals, correcting the vocabulary and language, pruning out all the wrong connections.
     
  3. Hutan

    Hutan Moderator Staff Member

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    Yes, if you have to use your brain a lot, it makes sense that blood flow is directed there at the expense of the periphery, in exactly the same way as, if you are running, the blood flow is directed to leg muscles.

    And, if you anticipate pain, it makes complete sense that blood flow will be reduced in the periphery. It would be adaptive to reduce peripheral blood flow when pain is expected, both so you don't bleed a lot from any break in your skin that might go along with the pain, and also so there is blood in your deep muscles for running away, and blood for your brain, so you can think well about getting yourself out of the situation.
     
  4. rvallee

    rvallee Senior Member (Voting Rights)

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    You just reminded me of something I was thinking about the recent study that found people anticipating the tilt-table test, how they found that, IIRC, the heart rate started increasing before the test started, in anticipation.

    And, yeah, obviously. That sounds like a damn smart system to me, that it knows something is going to happen and starts getting ready in anticipation for it. How else would it work? Of course that can be learned, it's a very smart adaptation if it can prevent loss of consciousness by preparing in advance. What's the point of being smart if you don't learn and adapt?

    I very much doubt this is conscious. It just seems like very smart evolution, and like some very smart people are saying, nothing in biology makes sense other than in the context of evolution. A physiological response that acts before it shuts down sounds like a very smart adaptation to me.

    And not just smart, the opposite would be a very dumb system. Like, you know that loss of consciousness could occur from this, know all the warning signs, and you don't react to it? Frankly it would be terrible if the brain didn't learn about things that can make it shut down and avoid it.
     
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  5. Hutan

    Hutan Moderator Staff Member

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    I had the exact same thought about that tilt-table study when I read the abstract of this paper. We've seen this a bit - the psychogenic proponents painting normal responses as pathological.
     
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  6. Peter Trewhitt

    Peter Trewhitt Senior Member (Voting Rights)

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    Stress is one of those potentially unfortunate words that has a number of distinct meanings which include both a psychologically neutral idea of exertion and the psychologically loaded idea of including anxiety, worry or even distress. It could be argued with justification that science needs a more precise vocabulary than general usage, however I strongly feel that is likely to be problematic when emotively loaded words such as stress are employed.

    I agree with @rvallee that this paper not only leaves the reader open to confusing the different meanings of stress but that the authors themselves have confused these two ideas:

    There is no necessary relationship between mental exertion and anxiety/psychological distress; it is possible to undertake an activity that requires high levels of mental exertion without becoming anxious or psychologically distressed or alternatively it is possible to become anxious without any preceding mental exertion.

    That is not to say that the two do not interact, mental distress can of itself involve mental exertion and certainly with myself unavoidable mental exertion in a situation where I am aware that I will struggle cognitively is not with its own anxiety. For example last weekend I attended an exhibition private view of work by an old friend I had not seen for over a decade. The exhibition involved flashing lights in a dimly light room with a complex sound track playing, then add to this a party type gathering. Ignoring any anxiety relating to Covid related risk, I went into that situation knowing it was pushing my ME brain to its limit in just focusing on one conversation at a time, so I also had to concentrate on not wasting what mental energy I had on worrying that communication might break down or me looking like a fool.

    The current study tells us something about mental exertion’s relevance to sickle cell disease but nothing about stress in the sense of anxiety or psychological distress other than that itself can be a component of mental exertion.
     
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  7. Mij

    Mij Senior Member (Voting Rights)

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    I didn't have mental stress/distress after mental exertion until I developed orthostatic impairment and PEM. I can feel a tight band around my forehead when I over exert mentally, it certainly feels like there is a lack of blood flow (microcirculation blood restriction) getting to my brain.

    I feel anxiety and stressed when I'm in an environment where I don't have control, or don't have a place to lie down to recover.

    The stressor disappears after I lie down.
     
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