The Gut Microbiome and Neurological Disease

Studies on the impact of the bacteria that live in our guts has exploded in the last 20 years. While most can understand how gut microbes can affect digestion and cause irritable or inflammatory bowel issues, some of the most interesting science of the last decade has looked at how gut bacteria affects our brains.⁣

Dysbiosis is a condition in which the normal bacterial environment has been disrupted. This means that important good bacteria may be deficient as is the case when patients take antibiotics. It can also mean that there is increased growth of pathogenic bacteria like E. Coli.⁣

Gut dysbiosis has been identified in neurological conditions like Alzheimer’s Disease, #parkinsonsdisease #autism as well as psychiatric conditions like depression and anxiety.⁣

Animal models have shown that replacing the gut bacteria of a healthy mouse with the bacteria of a sick human can actually reproduce the symptoms of the person in the mouse! It’s also been demonstrated that placing the healthy microbes of a healthy person can reverse the symptoms in a sick rodent. ⁣

3 mechanisms for gut-brain communication:⁣

1️⃣ 𝗩𝗮𝗴𝘂𝘀 𝗡𝗲𝗿𝘃𝗲 𝗧𝗿𝗮𝗻𝘀𝗺𝗶𝘀𝘀𝗶𝗼𝗻: The vagus nerve is responsible for monitoring the status of the gut. Products of bacterial metabolism can signal the vagus nerve which can alert the brain to pro or anti inflammatory states. ⁣

There are also theories that suggest that some proteins can travel from the gut into the brain via the vagus nerve, which is a proposed mechanism for how Parkinson’s Disease may evolve from the gut.⁣

2️⃣ 𝗜𝗺𝗺𝘂𝗻𝗲 𝗧𝗿𝗮𝗻𝘀𝗺𝗶𝘀𝘀𝗶𝗼𝗻: There’s a constant battle between the immune system and gut bacteria to prevent overgrowth. Good bacteria release products that can temper the immune system and reduce inflammation.⁣

Pathogens can trigger strong immune responses that promote inflammation, especially with a leaky gut.⁣

3️⃣ 𝗛𝗣𝗔 𝗔𝘅𝗶𝘀: Bacterial products can affect the release of hormones. This is particularly true for the hypothalamus and pituitary gland and how it affects cortisol from the adrenal glands.



Breathing for the Brain: Exhaling for Vagus


The the function of the autonomic nervous system is critical for the health of the body. The autonomic system consists of two branches.⁣

1. The sympathetic system which reacts to stress and dictates a fight or flight response.⁣

2. The parasympathetic system which calms the body down for resting and digesting.⁣

Both systems are important for survival and health. But many of us spend far too much time in fight or flight which comes with detrimental long term health impact.⁣

Prolonged and unchecked fight or flight is suspected to play a role in heart disease, stroke, diabetes, and Alzheimer’s disease. ⁣

It’s not easy to change our personalities & how we react to stress. But it’s important that if we have a lot of stress, that we keep the stress physiology in check.⁣

A simple and free way to do that, that takes no additional use of your time is changing your 𝗯𝗿𝗲𝗮𝘁𝗵𝗶𝗻𝗴 𝗽𝗮𝘁𝘁𝗲𝗿𝗻𝘀.⁣

Many of us breath in a way that is fast and shallow, but neurologically this can bias our sympathetic nervous system.⁣

When we inhale rapidly, our sympathetic nerves tend to fire more which keeps our heart rates slightly elevated.⁣

Breathing out has the opposite effect. It tends to activate our vagus nerve and slows down our heart rate.⁣

A simple way to get more parasympathetic activation from our vagus nerve is just to spend more time breathing out! ⁣

It’s too simple, but really effective.⁣

Here’s how you can work on this:⁣

1. When you are reading, watching TV, working on the computer, getting ready for sleep, start focusing on slowing your breath.⁣

2. Take normal breaths in, but start focusing on doubling the number of seconds breathing out. ⁣

If it takes 2 seconds to breathe in, spend a full 4 seconds breathing out. If it takes 3 seconds to breathe in, spend 6 seconds out.⁣

Try to go as slow as possible. ⁣

Initially the breath out will feel strange, but you are training yourself to breathe differently so it is normal to be uncomfortable.⁣

Within weeks of practice, your natural pattern will change, and this can have significant effect on your physiology.

What Happens in Vagus: Chronic Pain and Dysautonomia

I’ve been doing a lot of reading lately about the vagus nerve and the autonomic nervous system. We’ve been super fortunate to work with a handful of patients with POTS in the past 6 months with some really great and surprising results from taking a cervical and vestibular approach to care, and it’s driven me to learn more about this unconscious super system in the body.

While dysautonomia is considered a rare problem, there are actually certain types of patients that have a higher risk of having dysautonomia as a co-morbid condition. This includes neurodegenerative disorders like multiple sclerosis and Parkinson’s Disease, but the ground I want to cover is something that affects people as an invisible illness.

Today we’re going to breakdown the relationship between chronic pain and the vagus nerve.

Fibromyalgia, Chronic Fatigue, and Dysautonomia

Fibromyalgia and chronic fatigue syndrome (aka myalgic encephalomyelitis) are 2 conditions that are frequently associated with each other. Estimates as high as 75% of of fibromyalgia patients report fatigue as a major symptom and 20% of chronic fatigue patients also report having widespread body pain [source].

What’s unique about these disorders is that they both show an unusually high amount of dysautonomia compared to the general population. A review in the Journal of Clinical Rheumatology showed that patients with fibromyalgia frequently show scores reflecting autonomic dysfunction along with non-pain symptoms like light-headedness on standing (orthostatic intolerance), digestive complaints, excess sweating, and fatigue.

It’s also been reported in the Journal of Internal Medicine that patients with chronic fatigue syndrome frequently have postural orthostatic tachycardia syndrome (POTS) enough to classify the POTS patients as a distinct subgroup of chronic fatigue.

So why is chronic pain associated with this breakdown of the autonomic nervous system?

What Happens in Vagus….

The nervous system is classified into different branches. For ease of understanding, you have one branch that controls all of your muscles like your biceps, triceps, and quads called the somatic nervous system. You also have another branch that controls your organ systems called the autonomic nervous system.

The autonomic nervous system is further divided into the sympathetic nervous system and the parasympathetic nervous system. The sympathetic system is the one that causes the things you feel when you get stressed out. Rapid heart beat, sweating, high blood pressure, along with increased blood flow to your muscles. It helps you prepare to fight or escape danger. The sympathetic system is primarily driven by a bundle of nerves called the sympathetic chain.

The parasympathetic does the opposite. It forces you to breathe slowly, digest, breathe slowly, and think about reproducing. The parasympathetic system is mainly driven by your vagus nerve.

The Vagus Nerve has a direct connection to most of your body’s internal organ systems

These systems generally work in opposition to each other to set the tone for how your body is going to operate.

The vagus nerve is an special and unique nerve that travels from your brainstem into the bulk of your internal organ systems. It gives the brain a direct line of communication with your organ systems because your body generally wants to spend most of it’s time being parasympathetic. 


Because when your body is more parasympathetic it is able to breath easier, digest better, engage in sexual intercourse, sleep, and heal from injury.

The sympathetic system is designed to help you survive from an imminent threat, but your parasympathetic system is there to ensure that you can adequately heal and recover from that threat.

The more active the Vagus nerve is, the more likely your body is able to heal and recover. This isn’t just some pleasant billboard sticker either. Research has shown that increased parasympathetic activity is associated with higher survival heart disease and cancer. It’s also associated with improved recovery and decreased injury in athletes.

Most importantly for the patient in chronic pain, lower vagus nerve activity was associated with chronic pain compared to healthy controls. [Source] It’s also been shown that lower vagus activity can be associated with intensity of symptoms in patients with fibromyalgia. [Source]

Weak Vagus and Chronic Stress

Vagal activity is measured using something called heart rate variability (HRV). Many years ago, you could only measure heart rate variability from electrocardiograms (EKG) and measuring the distance between each heart beat. Today, there is no shortage of computer and even smart phone applications that have brought HRV to a wide audience.

In general terms, the higher your HRV is over time, the higher your vagal or parasympathetic activity. The lower your HRV is over time, the higher your stress or sympathetic activity.

If your body is in a chronically high state of stress, then it is going to:

  • Decrease blood flow to your organs
  • Increase exposure to your stress hormones (adrenaline and noradrenaline)
  • Decrease your stores of serotonin (feel good neurotransmitter)
  • Increase your blood sugar (diabetes)
  • Increase your blood pressure
  • Decrease your immune system
  • Decrease tissue healing

Why? Because if your brain thinks that it is in danger from attack, then it does not care about healing and immune function. It is strictly concerned about getting you out of danger.

When you have low HRV and high sympathetic activity, your body is at a distinct disadvantage when it comes to healing and resilience. While low HRV isn’t necessarily the cause of heart disease, cancer, fibromyalgia, or chronic fatigue, but if you have a low HRV then your body’s ability to adapt and overcome these conditions is compromised.

I’ll put that in bold text because that’s an important distinction:

When you have low HRV and high sympathetic activity, your body is at a distinct disadvantage when it comes to healing and resilience. While low HRV isn’t necessarily the cause of heart disease, cancer, fibromyalgia, or chronic fatigue, but if you have a low HRV then your body’s ability to adapt and overcome these conditions is compromised.

Bringing Vagus Back

There was an interesting study published in 2014 that used strength exercise as a treatment for patients with fibromyalgia. The study showed that patients with Fibromyalgia had significant improvements in pain and quality of life through a regiment of strength training, but no significant changes in HRV. The study was surprising, because exercise is one of the best, easiest, and cheapest ways you can improve your HRV, but the biggest surprise was in the conclusion. The study concluded that strength training was an effective therapy for patients with fibromyalgia, which is absolutely true, but also said that changing the autonomic nervous system is not a goal worth achieving in patients with fibromyalgia.

Knowing what you know now about the autonomic nervous system, it seems like a rational and reasonable goal for any patient because improving the autonomic nervous system improves the health and survival of patients regardless of what condition they have.

The best part is that vagal tone can be improved using non-invasive methods that include cardiovascular exercise, resistance exercise, breathing exercise, mindfulness training, non-invasive vagal nerve stimulation, and yes even upper cervical chiropractic.

By taking the focus away from just addressing the pain, and making the focus of care on the autonomic nervous system, it gives us the ability to affect the person as a whole, instead of just addressing a symptom. By taking people away from their condition, and returning them to their bodies.


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