Brain Drain Microbial Invaders
Got Brain Drain? How Microbial Invaders Can Steal Your Memory, Focus + More
By Dr. Bill Rawls Posted 02-12-2021

You’ve likely heard about the microbiome as it relates to gut health, but did you know microbes — bacteria, viruses, fungi, and protozoa — occur in the brain as well? As a matter of fact, the latest groundbreaking news in the world of neurological science, in my opinion, is the discovery of microbes in human brains.

It’s well-recognized that infections of the brain can cause severe, acute illness such as meningitis (inflammation in the lining around the brain or spinal cord) and encephalitis (inflammation of brain tissue). But these new findings could shed light on the role that microbes play in the gamut of brain health concerns, from neurodegenerative diseases such as Alzheimer’s to chronic diseases associated with neurological symptoms such as fibromyalgia, chronic fatigue, and chronic Lyme disease and even milder cognitive symptoms we generally write off as signs of aging such as memory problems, inability to focus, mood swings, and brain fog.

Senior exhausted woman having headache sitting on sofa at home.

I believe that understanding this connection is the key to maintaining brain health and preventing unwanted symptoms and cognitive decline. Here’s what you need to know, starting with the evidence of microbes taking up residence in the brain.

Proof That Microbes Invade the Brain

About four years ago, researchers in Canada were searching for bacteria in autopsy brain specimens from people who had died of multiple sclerosis (MS). What they found, according to their study in the journal Nature, was astonishing: Not just one or a few species of bacteria, but hundreds of different bacterial species inhabiting the brain!

Although every sample contained bacteria, each one carried a slightly different spectrum of microorganisms. Notably, pro-inflammatory bacteria prevailed in the MS group. Those microbes were associated with key characteristics of MS, including inflammation and demyelination, a process that damages myelin, the protective, fatty substance that wraps around the nerves in the brain.

Brain CT scan x-ray film

Perhaps even more remarkable, the researchers found a similar array of bacteria in the control specimens, too. The controls were brains from people who had died of something other than MS. Like the MS brain tissue, they also contained many different species of bacteria. The difference? Friendly flora — microbes that live in our body without causing disease — dominated the brains of the control group.

Surprised by the findings of so many different species of bacteria, the researchers double-checked their methods for the possibility of contamination, but ultimately found that the results were authentic. And soon thereafter, similar findings were noted in an independent 2017 study from the UK.

This time, researchers were analyzing autopsied Alzheimer’s brains. And just as with the MS study, they discovered a broad distribution of bacteria in each specimen. Again, the control specimens from people who had died of something other than Alzheimer’s also contained a wide range of microbes. And, as with the MS study, the most striking difference between the two groups was the predominance of pro-inflammatory bacterial species in the diseased Alzheimer’s brains.

These studies raise a crucial question: Do all brains contain microbes? When I consider one more study, some 2018 research from the University of Alabama, the answer is likely, yes.

Here, researchers evaluated vascular changes in the brains of 34 people who died of non-infectious illnesses. Across the board, they encountered a range of bacterial species in different areas of the brain. Yet again, each and every specimen contained a variety of microbes. The microbes found in these particular studies were inside brain cells (intracellular or stealth microbes), and the specific species were not identified.

The extraordinary findings of these three studies confirm that the collection of microbes in the human body, called the microbiome, is more extensive and intricate than anyone could have ever imagined. Who would have thought the normal scope of the microbiome extended into the brain? But apparently, it does.

Why bacteria might want to invade brain tissue isn’t difficult to answer — brain tissue provides a wealth of nutrients. It’s abundant in the resources that bacteria need, such as collagen, myelin from around nerve sheaths, vital nutrients, and energy.

nerve cell in a blue background, 3D illustration

How they got there, however, is a more challenging question. Most of the microbes found in the studies were common to the gut and skin. Researchers speculate that they simply traveled through the blood, and there’s some evidence to support their thinking.

In a scientific investigation published in 2015, researchers documented that gut bacteria can cross the gut barrier into the bloodstream and hitch a ride inside red blood cells to be transported to tissues throughout the body. Though the study found it was more pronounced in people with dysbiosis — an imbalance of microbial communities in the body — apparently it happens in everyone at a low level.

Other studies have documented that microbes on the skin can pass through nasal passages to end up in the bloodstream and even the brain. Interestingly, one of the proinflammatory microbes commonly found in the Alzheimer’s brains was P. acnes, a common skin bacteria associated with skin acne. In other studies, P. acnes has also been found in prostate disease, infection of heart valves, and 70% of people with sarcoidosis (an autoimmune illness).

This would imply that the gut-blood barrier and the blood-brain barrier aren’t nearly as protective as was once thought, especially considering each sample in every study revealed so many different species of bacteria. Plus, it should be noted that these three studies only checked for bacteria — the prevalence of viruses may be even higher.

How Microbes in the Brain Trigger Symptoms

Regardless of where and which microbes inhabit our bodies, our relationship with them is built on a foundation of sharing. When that relationship is balanced, we share some resources and nutrients with our microbes, but not enough to cause damage to our tissues. In return, many of our microbes reciprocate by providing us with nutrients such as vitamins B12 and K and other benefits.

Other microbes, however, are not so generous. Remember, the microbiome is a large menagerie of microbes, and there are always more aggressive bacterial outliers that have the potential to take more than their share if they’re not contained.

We all have these outliers — freeloaders looking for an easy meal. We pick them up as we go through life, from contaminated air particles, food and drinks, intimate contact with other people, skin abrasions, and bites from insects such as ticks and mosquitoes.

virus cell in blue background, 3d illustration

Outliers want the same thing as all the rest of our microbes: to share the abundant resources that we have to offer, especially in the brain and nervous tissues. The vast majority of them do not have a high potential to cause severe, acute illness. They quietly enter the body and join in the mix of other bacteria sharing in the resources of the body.

Which brings us to the immune system, the governing body over our shared community with our microbes. When the immune system’s functions are healthy, it keeps our microbiome in check: Favorable microbes flourish, and adverse ones are suppressed. If the activity of the immune system is compromised, however, outliers multiply and take more than their fair share.

If microbes from the skin and gut can freely enter the brain, as the three studies above imply, then outliers can, too. When outliers in brain tissue abound, the result is neurological inflammation. Because many microbes value myelin as a resource, damage can include demyelination of nerve sheaths.

Horizontal portrait of senior woman with gray hair sitting alone in departure lounge looking away thinking of something, copy space

An initial surge of microbes in the brain, coupled with low levels of inflammation, likely explains many of the milder cognitive symptoms we sometimes experience as we get older, such as forgetfulness, lack of concentration, mood swings, and mental fatigue. As the inflammation and population of microbes grows in the brain, it can cause a wide range of neurological symptoms, including chronic pain, numbness and tingling in the hands and feet, burning sensations in the hands and feet, loss of hearing, ringing in the ears, and changes in vision.

Microbes in the Gut Affect Cognitive Function, Too.

It’s important to note that microbes don’t necessarily have to enter brain tissue to influence the brain. Bacteria in the gut produce a range of neurotransmitters, including glutamate, serotonin, GABA, and dopamine. They use these neurotransmitters to communicate with each other and intestinal cells.

The same factors that weaken immune function also allow for a shift in gut flora toward harmful microbes, which alters microbe signaling. Those factors include chronic stress (think: constant work deadlines, financial concerns, COVID-19 anxiety), exposure to environmental toxins like pesticides and chemicals from plastics, and eating a diet laden with carbohydrates and refined foods.

This shift toward pathogens (gut dysbiosis) generates inflammation and favors production of excitatory chemical messengers that activate the sympathetic nervous system (fight-or-flight response). Not surprisingly, depression and anxiety have been associated with altered gut microbe signaling.

To Keep Your Brain Healthy, Start with Herbal Solutions.

Of course you want to be free of frustrating cognitive symptoms like fuzzy memory and focus, and addressing them is certainly part of the solution. But if you really want your brain to function at optimal levels, you have to address the underlying causes of your symptoms by balancing the microbiome and fortifying the immune system.

That’s where the right herbal therapy can really help, by offering four key benefits:

  • Easing symptoms
  • Suppressing microbes and restoring balance to the microbiome
  • Strengthen immune system functions
  • Reducing inflammation

1. Address the Symptoms.

For managing cognitive and neurological symptoms, a plant extract called CBD (cannabidiol) from hemp in oil form is one of the best options available. CBD affects a system in the body called the endocannabinoid system, which oversees a wide range of functions in the body, including brain neurotransmitters.

CBD oil, hemp oil capsules and cannabis leaves on green background. Flat lay, copy space. Alternative medicine. Natural supplements, treatment.

Taking CBD oil calms an irritated nervous system, which leads to a reduction in anxiety, depression, and pain. CBD also helps restore restful sleep — an absolute necessity if you want your brain to function at optimal levels. Use of CBD is not associated with euphoria, and scientific studies have shown that CBD from hemp has no potential for habituation.

Many herbs compliment CBD oil. Herbs called adaptogens not only support the immune system, but they also balance hormones and neurotransmitters in the body. One of the most well-known adaptogens for protecting the brain and neurological function is ashwagandha. Other herbs for calming an agitated brain include bacopa, lion’s mane mushroom, and ginkgo biloba.

2. Suppress the Microbes.

While antibiotics might seem to be a solution worth considering, remember that you’re not dealing with an acute bacterial infection in the brain but rather a disruption of the entire microbiome balance. Which means synthetic antibiotics can make the situation worse instead of better: They suppress normal flora and allow harmful microbes to multiply, especially in the gut. This ultimately will set you back.

Herbal therapy offers a more workable solution by promoting microbiome balance while also supporting the immune system so it can do its job. Antimicrobial herbs are beneficial for suppressing harmful microbes and restoring balance to the microbiome, without disrupting normal flora.

Bark of the Uncaria tomentosa plant - Text space

There are many herbs that fit the bill, and most contain bioactive chemical components that cross into the brain. An excellent one to start with is cat’s claw, a woody vine from the Amazon.

Cat’s claw is known for not only its microbiome-balancing properties, but also its ability to support healthy levels of immune system cells, including white blood cells, B and T lymphocytes, and natural killer (NK) cells. Other great herbs to consider include andrographis, Japanese knotweed, sarsaparilla, allicin from garlic, and berberine.

3. Support a Strong Immune System.

Many herbs have immune-modulating properties — the ability to calm an overactive or overtaxed immune system. This is important for reducing inflammation, but also for bolstering the immune system’s ability to manage the diverse load of organisms in the microbiome. Herbs that can support and nourish your immune system include ashwagandha as well as cordyceps, reishi mushroom, and Chinese skullcap.

4. Reduce Inflammation.

Herbs important for reducing inflammation and promoting healing include turmeric, boswellia, and devil’s claw. Essential oils administered by aromatherapy are also excellent for reducing brain inflammation. Top choices include frankincense, melissa (lemon balm), and rosemary.

Go Beyond Herbal Therapy.

Because the brain consists primarily of fat, anti-inflammatory substances that are fat-soluble work best to quell irritation and inflammation. At the top of the list are omega-3 fatty acids from marine sources. DHA, one of the omega-3 fatty acids in marine oils, has been associated with improved motor and cognitive function, mood, and focus.

A word of caution when taking omega-3 fatty acids: Do not exceed more than 6 grams of fish oil daily. Greater amounts have been associated with an increased risk of hemorrhagic stroke (blood vessel rupturing in the brain). If you have a family or personal history of bleeding disorders, you bleed easily, or your blood doesn’t clot properly, consult with your healthcare provider before taking omega-3 fatty acids.

red krill capsule held between two fingers

If you want an alternative to fish oil, krill oil is one of the best ways to supplement omega-3 fatty acids. Krill oil occurs as phospholipids, the form most readily absorbed and utilized by the body, instead of triglycerides found in fish. It takes about 60-70% of krill oil to generate the same blood omega-3 levels as compared to fish oil.

There are also a number of foods to consider adding to your diet to encourage brain health. The following foods contain a variety of nutrients, which can be beneficial in improving neurological function:

  1. Eggs are a good source of lecithin and choline, both essential brain nutrients.
  2. Salmon supplies omega-3 fatty acids.
  3. Oysters supply omega-3 fatty acids and minerals, including zinc, an essential nutrient for brain function.
  4. Olive oil offers antimicrobial properties and monounsaturated fats, which are anti-inflammatory.
  5. Coconut oil provides medium-chain triglycerides (MCTs), which promote nerve tissue repair.
  6. Ghee (clarified butter) provides saturated fat, which in small amounts (1-2 tsp per day) helps support healthy brain tissue.
  7. Avocados and nuts provide healthful fats that play an important role in brain health.

Finally, it’s very important you address the lifestyle factors that are contributing to weakened immunity and allowing microbes to flourish in the brain. Do these four things, and you’ll go a long way toward shoring up your immune defenses and restoring healthy, normal brain function:


Nourish Your Body.

A healthy diet for immune system support should focus on whole foods, ample vegetables that are rich in phytochemicals (beneficial plant chemicals that support your body’s systems and functions), and healthy fats. Keep processed foods, grain-fed meats, excess carbohydrates, and unhealthy fats to a minimum, and fill at least 50% of your plate with veggies.


Purify Your Environment.

Reduce your exposure to environmental toxins whenever you can. Opt for organic foods when feasible, filter your water and air, and choose non-toxic cleaning supplies and beauty products.


Calm Your Mind.

Adopt some daily stress reduction and management techniques such as practicing meditation, doing yoga, walking outdoors, or even napping.


Activate Your Body.

Doing gentle, restorative exercise every day helps keep the body moving and counters the modern-day pitfall of being too sedentary.

The Bottom Line

Brain inflammation and irritation due to microbial activity may contribute to milder cognitive symptoms such as forgetfulness, brain fog, and lack of focus that steal your confidence and hold you back from living your fullest life, plus it can potentially lead to serious chronic and degenerative illnesses.

To support your brain’s health and keep it functioning optimally now and long term, remember this: Pair the right herbs with stress reduction techniques, a healthy diet, and plenty of sleep to boost your immune system and keep the microbes and inflammation in check.

The Cellular Wellness Solution

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About the Medical Director
Dr. Bill Rawls
Dr. Rawls is a licensed medical doctor in North Carolina and a leading expert in integrative health. He has extensive training in alternative therapies, and is the Medical Director of Vital Plan, a holistic health and herbal supplement company in Raleigh, NC.
  • Dr. Bill Rawls


    Dr. Rawls is a licensed medical doctor in North Carolina and a leading expert in integrative health. He has extensive training in alternative therapies, and is the Medical Director of Vital Plan, a holistic health and herbal supplement company in Raleigh, NC.

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