How stress rewires the brain From Cyto

How stress rewires the brain

It’s 2017. Who isn’t exposed to some kind of stress or another, either continuously or just “part-time”?

This week’s blog discusses common causes of stress and how it can ‘rewire the brain’. The article is written by expert practitioner Miguel Toribio-Mateas, who will be speaking at our next Cytoplan Practitioner Education Event on 7th October. You can find out more about the event via this link.


Jobs, finances, relationships, even pets. I love my two Labrador boys to pieces. They do give me a huge amount of pleasure when they behave, but they can also stress me out, for example, when they decide to start barking at the postman in the middle of a work phone call.

Another type of stress I see a lot of is anxiety about one’s own health. Being stressed about a condition you’re suffering from and anxious about getting better can be all consuming and unfortunately a growing number of people I see in the clinic have fallen into that vicious circle.

Whatever your stressor, whether it’s dogs, illness or anything else, prolonged psychological stress tends to be accompanied by elevations in blood cortisol known as, “the stress hormone”. This leads to a potential fight-or-flight response we are designed to experience as a short-lived reaction to allow us to either fight or flee (literally) becoming chronic. The results: we’re on edge permanently, sometimes without even knowing why.

If you’ve reached that kind of psychological state where everything is a chore and you’re easily irritated, fatigued or even “not bothered”, it is very likely that cortisol has started to “rewire your brain” in a maladaptive way.

What does this mean and how does it happen.

In fact, why does it even happen? Well, cortisol has a number of jobs. It is secreted by the adrenal glands as a messenger to tell muscle and liver tissue to release sugar (stored in these tissues as glycogen) into the bloodstream. That sugar (or glucose) can then be transformed into energy fairly quickly by mitochondria (the tiny power plants inside every single cell of your body) supporting your ability to fight or to flee, whichever of these two actions you might choose to engage in. Only that a lot of the time you have nothing/no one to fight or flee from because whatever is triggering your anxiety is entirely in your head. This doesn’t mean you are imagining things. It’s a loophole in how we are wired to react to stress that evolution hasn’t taken into account. For example, we’ve not evolved (yet) to overcome the fear of missing out (FOMO). My iPhone keeps pinging. It’s Twitter, Instagram, email, phone calls, meetings…  If it wasn’t for good old cortisol (and his hormonal brigade adrenaline, and noradrenaline) I couldn’t react to all of that. So I don’t want you to think of cortisol as the bad guy in the movie. It’s just learning how to tame it that’s the important thing, so it doesn’t run wild, running you down with him!

Cortisol is released also as a natural anti-inflammatory substance whenever there’s inflammation to be dampened down, which is partly why inhibiting your ability to react to stress by means of cortisol reduction may not be the obvious answer you may already be thinking of. In fact, cortisol has many other roles and is involved in the stabilisation of blood pressure and the dilation of the bronchioles in the lungs. It is also one of the molecules that set the pace of the heartbeat and the activity of the digestive system. If you’re stuck in a fight-or-flight kind of situation, it is most likely that you’ve felt your heartbeat pound harder than normal, or even get palpitations at certain times? Equally, your bowel may not move as quickly or efficiently as you’d like it to. These reactions are most likely related to the activation of your “stress system” with cortisol driving these type of symptoms.

Figure 1. A summary of organs outside the nervous system that responds to the activation of the stress system.

Stress and resilience

Stressful experiences are not always “bad” for the brain. In fact, in the short term, being exposed to a stressor can lead to growth, adaptation, and new learning. The reason this happens is that the brain is designed as an allostatic system, i.e. a system that is able to find balance (normally referred to by the technical term “homeostasis”) in a dynamic environment. This allostatic or dynamic balance enables you to not only cope with stressful experiences but to adapt to them, regulating your stress levels accordingly, and learning how to manage them. In doing that, new connections are created between neurons that imprint this pattern in the brain so that you know how to deal with the situation in the future. This rewiring is referred to as neuroplasticity and neuroscientists refer to a situation where a stressful situation leads to learning and growth as “adaptive neuroplasticity”. The perfect example is preparing for an exam that you must pass to get a place in university, a promotion or the “Life in the UK” test that’s necessary to get British nationality, like I had to do recently when I decided to apply to become a dual British / Spanish citizen after living here for 23 years. You’re under pressure because you really want to get that job, or that place on that course, or to increase your exotic rating by holding two passports. Cortisol is likely to be high, mobilising all resources necessary to keep you alert. Your pulse will be fast, you’ll be full of beans, you may even feel you need to go to the toilet more frequently as being in that acute fight-or-flight situation, your brain sends signals to your gut that it needs to be empty in case you need to escape from this perceived stressor. The fact is that your brain doesn’t differentiate between the exam and a lion. The stress of the exam is in your head and a hypothetical lion would be real, but really your brain “sees them” as the same thing and responds to them in exactly the same way. Your bronchioles expand so you can get more oxygen into your muscle in case you need to fight or flee the danger. You sit the exam and as the bell tells you it’s time to put your pen down, both your body and your brain crash. Mission accomplished. All those resources that had been mobilised to allow you to achieve your goal are now terminated, and the connections between neurons that were created to enable that extra learning bandwidth become semi-permanent fixtures of your “new” brain.

Figure 2. As illustrated by its response to increased physical activity, the human brain has a considerable degree of plasticity and resilience (reproduced with permission from McEwen and Gianaros (2011) Annu Rev Med. 2011; 62: 431–445. doi:10.1146/annurev-med-052209-100430).

However, when the activity of allostatic systems is sluggish, ineffective, prolonged, or not terminated promptly, allostatic systems can impair mental and physical health through their maladaptive effects on brain plasticity and metabolic, immune, and cardiovascular pathophysiology (allostatic load).

Maladaptive response to stress: When rewiring goes wrong

If your stressor doesn’t go away as in the example of the exam above, and becomes chronic, e.g. worrying about job security, financials, your own health or that of a family member you’re caring for, etc. the effects of stress become problematic for health in the long term, particularly when they’re uncontrollable, unpredictable, and difficult to cope with because of a lack of supportive personal, social, and environmental resources.

In fact, neuroscientists have found that if you’re having to deal with stressful experiences every day the risk of your resilience against physical and mental illness diminishing or even “breaking” is much higher than if you were dealing only with acute stressors. So a little stress is good, but a lot of it is not. In the adult, as well as in the developing brain structural as well as neurochemical changes take place as a consequence of all experiences, including those that are stressful. Modern neuroimaging techniques show that loss of resilience is a key feature of disorders of stress adaptation such as anxiety and depression. Both of these conditions are characterised by maladaptive neuroplasticity, a situation where the connections between neurons I referred to before having established a negative pattern in the brain that has become the default.

Figure 3. Maladaptive neuroplasticity doesn’t only affect the brain. It has a number of ramifications across body systems (reproduced with permission from Peterson (2012) Neural Plast. 2012;2012:516364. doi: 10.1155/2012/516364).

What can you do to restore the “adaptive” state?

The brain is the central organ of stress and adaptation. It regulates and responds to a number of factors that contribute to this ongoing balance or allostasis. When the stress system is dysregulated and overused more wear-and-tear of the brain itself leads to subsequent loss of balance in other body systems due to increased allostatic load. Imagine yourself as a boat carrying a heavy load across from the UK to Ireland. Suddenly a helicopter drops another couple of crates for you to carry, making you heavier than you had anticipated and triggering some damage on your hull that lets water in as you start to sink. You get rid of some of the load you need the least by throwing it in the sea, and that makes matters slightly better, before another helicopter drops another couple of crates. Interventions that help you manage your allostatic load include improving your diet. With the right nutrients you’ll not only lighten your load, but also fix your hull so water no longer makes you more prone to sink. Some key nutrients are poly and monounsaturated fats from fish and olive oil, respectively, as well as methyl factor vitamins like folate, B12 and B6, and plant phenols (antioxidants in “old school” science) that help the brain directly and also indirectly via gut-brain communication. Additionally, regular physical activity and having access to a social support and integration, e.g. close contact with friends and family, all help you manage that load so you can continue to sail without having to worry constantly about the excess load and the damage it can cause. A sustainable period of balance promotes adaptive or positive plasticity that can be long-lasting.

Figure 4. Some of the interventions known to help restore adaptive neuroplasticity (reproduced with permission from Peterson (2012) Neural Plast. 2012;2012:516364. doi: 10.1155/2012/516364).

Some of the areas of the brain that show both adaptive and maladaptive forms of plasticity, i.e. that are affected by allostatic load, and are implicated in stress-related vulnerability to chronic health conditions include regions of the prefrontal cortex, hippocampus, and amygdala. At the upcoming event with Dr John Briffa in October I will be discussing in more detail how we can interact with these brain areas by means of simple, safe, and science-based nutrition and lifestyle interventions that help prevent and reduce the impact of the maladaptive response to stress on the health of the brain and the rest of the body. Hope to see you there.


Miguel is a doctoral researcher in cognitive ageing who’s experienced the research process from the laboratory bench – having completed a lab-based Masters in Clinical Neuroscience focusing on brain ageing – to the delivery of scientific findings in the consultation room, delivering quality individualised nutrition care to his clients from 2009. Miguel’s background includes 15+ years in senior training roles in life sciences and medical publishing, and he has trained scientists and researchers around the world.


A Cytoplan Practitioner Education Event – Saturday 7th October, 10.00am – 5.00pm.

Riverside Building, County Hall, London, SE1 7PB

Miguel will be speaking at our Cytoplan Practitioner Education Event on 7th October 2017, on how to manage stress, promote resilience and support neuroplasticity. To find out more about this event, please follow this link and book this week to get your early bird tickets.


With many thanks to Miguel for this blog; if you have any questions regarding the health topics that have been raised please don’t hesitate to get in touch with me (Clare) via phone; 01684 310099 or e-mail (clare@cytoplan.co.uk).

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