Its obvious that both are related(adrenaline and anxiety) but which causes which? What (I think) I know:

  • Anxiety accelerates the hearth rhythm due to the feeling of fear. It makes the body believe that there is a need to spend an enormous amount of energy getting away(someway) so it cuts the blood flow in the cognitive parts of the brain and sends more blood to the other muscles, it also releases adrenaline in the blood due to the increasing need of energy(even if there is no real need).

  • Adrenaline, (when released) makes the hearth rhythm increase and gives some "extra" power to the muscles by cutting the blood flow in the brain and giving it to the muscles. With the lost of blood flow in the brain the person loses a considerable part of the cognitive capacity (among other things), causing the person to have some feelings (like anxiety) and unreal thoughts.

Resuming my question: Anxiety results in a release of adrenaline, but adrenaline also makes the brain malfunction causing some feelings like anxiety. It makes sense but it is an infinite cycle. What is the false (and why), or if both are true then how does it ends?

  • $\begingroup$ Related but not a duplicate: cogsci.stackexchange.com/questions/183/… $\endgroup$ Commented Dec 23, 2012 at 5:52
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    $\begingroup$ Check out this article on anxiety: newsmaxhealth.com/dr_blaylock/Anxiety_Brain_Function/2011/04/21/… The article mentions stress and inflammation , but there is not a word about adrenaline. Maybe you were thinking of being startled or fight/flight? $\endgroup$
    – Alex Stone
    Commented Dec 24, 2012 at 3:28
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    $\begingroup$ "It makes sense but it is an infinite cycle. What is the false (and why), or if both are true then how does it ends?" - Both, and it's only an infinite cycle if you don't have a parasympathetic nervous system to modulate that adrenal response. But I don't have the references to make this an answer. $\endgroup$
    – BenCole
    Commented Dec 24, 2012 at 17:08
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    $\begingroup$ @BenCole Go for it - en.wikibooks.org/wiki/Human_Physiology/… $\endgroup$ Commented Dec 25, 2012 at 3:32
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    $\begingroup$ I am not totally enlightened(my fault i am not enough cognizant of the subject to understand). Please explain the "have a parasympathetic nervous system to modulate that adrenal response" part in a few simple words, and I'll accept the answer. $\endgroup$
    – SOMN
    Commented Dec 25, 2012 at 3:44

2 Answers 2


Sorry for the delay getting to an answer - the holidays have been super busy for me this year.

If you feel up to it, definitely check out the link @ChuckSherrington posted in the comments. That has more information than you'll need for a while.

Getting down to business: The answer to your question is both!

Since your question assumes that both are related and affect each other, I won't go into how they do that.

However, to clear up some misconceptions:

It's not a 1-to-1 cycle.

That is, the "amount" of anxiety reduced by reducing adrenaline is not the same as the amount of adrenaline reduced by reducing anxiety. Similarly, the amount of anxiety created by inducing adrenaline is small compared to the amount of adrenaline created by inducing anxiety.

There are other factors at work

This is where the "parasympathetic" thing comes in. The human nervous system is actually two systems (broken up into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS), though the PNS is often broken down further).

One of the component parts of the PNS is the Autonomic Nervous System. This carries out the largely unconscious functions of daily life: breathing, heartbeat, digestion, etc. It is further split into two components: the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (pSNS).

A very rough and reductionist analogy would be to say that these two, together, are like two springs one either side of a ball (or something) - they keep each other regulated and in balance.

The SNS is responsible for very fast, excitatory activity. Fight or flight, for example. The adrenal response is part of the sympathetic nervous system.

The pSNS is a lot slower. One of it's primary functions is to return the body to a relaxed state after it was provoked in an excited state.

From the wiki-books article @ChuckSherrington posted:

While an oversimplification, it is said that the parasympathetic system acts in a reciprocal manner to the effects of the sympathetic nervous system; in fact, in some tissues innervated by both systems, the effects are synergistic.

So as you hopefully have seen, as normal-functioning humans (which, to live, you must have both a SNS and a pSNS; it's not a question), you have a modulation response which keeps the adrenal response (the base response to a threatening stimulus that prepares the body for fast action) from getting out of hand.

Now, lastly, a disclaimer of sorts:

The link between neural activity and thoughts is tenuous at best! Many people are involved in many flame wars over the link between neural activity and phenomenology (experienced reality). The most direct view, and a very common one (from what I can tell) is the view that neural activity is reality itself. That is, our existence, our lives, our individual personalized reality, is neural activity itself.

But you will have to decide that question for yourself, because this is not a philosophy question/answer.

What's important is that the link between having thoughts and having feelings is not well understood. So adrenaline may make you nervous, but it may give Susie Randomgirl a panic attack (believe it or not, I know someone who can work themselves into a panic attack, every time - and they still don't get that they do it to themselves).

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    $\begingroup$ A good answer. The only thing I would disagree with the autonomic nervous system being in control of coordination. This is largely the role of the vestibular system and cerebellum which fine tune the motor output via projections to the brainstem, which then has a direct influence over the spinal interneurons and motor neurons. All of those pathways are considered part of the CNS. $\endgroup$ Commented Dec 29, 2012 at 1:38

I don't think a causal relationship between the two has been established yet. I did read about an experiment conducted by Ulrich Bolm Androff, where the blood samples 10 physicians and psychologists were collected at 2 different times, once after they gave a public speech and once at the same time, on another day, and it was found that levels of epinephrine were found to be higher at the time directly after the speech was given. This does show a corelation between an anxiety inducing situation and levels of epinephrine, however, causal relationship cannot be established.


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