[ExI] atrophy or hypertrophy

Rafal Smigrodzki rafal.smigrodzki at gmail.com
Fri Oct 2 08:41:27 UTC 2015

On Wed, Sep 30, 2015 at 11:51 PM, spike <spike66 at att.net> wrote:

> When a threat looms up before us, we get a shot of adrenaline, as the old
> familiar fight or flight mechanisms do what they do so well.  It gives us a
> little boost in strength and speed, suppresses the pain receptors and such
> as that.
> Adrenaline does more than that however.  It plays a role in immune system
> reactions to infection for instance.  So if the adrenal system doesn’t work
> right, it is more serious than your becoming a boring snoozy apathetic
> person.
> We have adrenal glands above our kidneys, but there are other cortisols
> and hormones and things produced by the hypothalamus and the pituitary
> gland which enable to adrenals to do what they do.  (Dr. Rafal, do I have
> that approximately right, in terms even a controls engineer can grasp?)
> If so, imagine the following scenario.  Suppose a guy retires from a
> rewarding career, so he has no 9 to 5 and no compelling reason to seek
> another one.  He has hobbies and works out and does things, writes code and
> stuff so the guy isn’t bored.  He has no schedule and just does whatever
> the mood suggests.  He isn’t sniffing around at the local fauna, so no risk
> of his bride catching him at anything untoward, no risk of an IRS audit
> (because he isn’t earning any money) no risk of really anything: he lives
> in a safe area with no visible gangs or scruffy looking dudes any of that
> sort of thing, he sold his last racing motorcycle several years ago and now
> rides only touring bikes in a sedate manner, he has a home life in which a
> harsh word is seldom uttered, he has a life filled with inner peace and
> serenity, completely by accident: it really just happened that way.  The
> fight or flight mechanism is seldom triggered because there is no one to
> fight and no reason to flee.
> Question: what happens to that guy’s adrenal system?  Does it
> hypertrophy?  Since the system evolved to deal with risk, in the absence of
> threats does it fish around for dangers that aren’t even there, triggering
> at every little spider or imaginary shadow of threat?  Or does the whole
> system atrophy, like a muscle which is seldom called upon to do anything,
> becoming withered, weak and ineffective from disuse?

### As far as I can tell, there is very little if any research directly
assessing changes in adrenal mass as a function of stress levels in humans,
since small changes in adrenal mass are rather hard to measure. A more
commonly used measure of response to stress is the level of corticoid
hormones. It is known that corticoid hormone levels are higher in persons
under sustained psychosocial stress, such as being the caregiver of a
demented person, compared to matched non-stressed individuals.

Higher corticoid levels are usually an indicator of higher activity in the
HPA axis (hypothalamic-pituitary-adrenal). An increase in stress is
detected by the hypothalamus, which then releases CRH, which triggers
release of ACTH by the pituitary, which finally stimulates production of
corticoids in the adrenals.

Under most circumstances, the mass of the adrenal cortex, which produces
corticoids, tends to increase when the adrenals are more stimulated, for
example in patients with Cushing's disease. We might then expect that there
would be some increase in adrenal mass in response to stress, and that,
conversely, there should be a mild reduction in adrenal mass when stress
levels are reduced. There are exceptions to this rule but they are unlikely
to be relevant to the question you posed.

So, I would expect a mild loss of adrenal mass in response to the
completely laid-back lifestyle. You are however unlikely to experience
severe adrenal atrophy, since even under perfectly non-stressful
circumstances there is a basal HPA activity level that keeps your adrenals

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