Understanding this delicate yet well-evolved biological barrier's anatomy, biochemistry, function, and challenges is vital for better cognitive, neurological, and mental health while preventing associated disorders.
This story does not include health advice. It is for information, inspiration, and awareness purposes.
When researching the blood-brain barrier and intestinal permeability in the early 1990s, which are now known as a leaky brain and leaky gut, I learned about major symptoms like brain fog affecting cognitive abilities (memory, attention, and task switching), which happened to me. But more importantly, a leaky brain might also cause neurological and mental health issues. I have written about leaky gut before.
A 2023 paper in Biochemical Society Transactions informs that blood-brain barrier dysfunction is implicated in many neurological diseases, such as stroke, Alzheimer’s disease, multiple sclerosis, and brain infections. Among other mechanisms, inflammation and/or flow disturbances are major causes of BBB dysfunction in neurological infections and diseases.
The growing literature mentions other symptoms of BBB dysfunction, like chronic fatigue, headaches, sleeping difficulties, mood disorders, anxiety, schizophrenia, depression, peripheral neuropathy, seizures, ADHD, and muscular sclerosis. I recently documented a case study of a friend who recovered from a brain fog, so lifestyle habits can help.
Mitigating risks and prevention is the best approach to being aware of the five items I will cover in this story. However, when we have these symptoms, especially when experiencing brain fog, we need professional support to identify the root causes of blood-brain barrier permeability by getting biomarkers checked and the condition addressed holistically.
This story has three parts. The first introduces the key points of the brain-blood barrier, the second highlights its significance, and the third explains how to protect it based on what we know so far. As the topic is comprehensive and complex, I will distill vast information by only focusing on the critical aspect in simple language that anyone can understand.
The brain protects itself with a robust yet delicate brain-blood barrier system. This well-evolved barrier separates the bloodstream and its intercellular fluid and regulates the entry of molecules between the bloodstream and the brain. Multiple factors can compromise its integrity and function, which I will articulate in this story.
What is the blood-brain barrier briefly?
The blood-brain barrier (BBB) is a protective barrier in the central nervous system composed of tightly joined endothelial cells lining brain capillaries. Supported by pericytes and astrocytes, it selectively allows essential molecules like oxygen, glucose, and ketone bodies to pass while blocking the entry of harmful substances, maintaining brain health and function.
This NIH Book informs that
The blood-brain barrier was first described by Paul Ehlrich in 1885. It is a highly selective semi-permeable membrane between the blood and brain interstitium. This unique barrier allows cerebral blood vessels to regulate the movement of molecules and ions between the blood and the brain.
As documented in a 2005 paper, antibodies cannot efficiently penetrate the blood-brain barrier due to their size. Only specific antibiotics can pass through. In situations where direct brain access is necessary, drugs may need to be administered into the cerebrospinal fluid, allowing them to cross the blood-cerebrospinal fluid barrier and reach the brain.
According to this BMC paper,
BBB is a specialized structure composed of tightly connected endothelial cells forming the cerebral capillary wall. These endothelial cells are supported by surrounding pericytes, astrocytes, and the basal lamina. You can learn about these anatomical structures and biomarkers from this comprehensive paper.
Scientists and clinicians try to understand how these different cell populations interact to regulate the barrier properties because they indicate how the brain functions during health and disease.
This unique assembly maintains the remarkable selectivity of the BBB, allowing it to restrict the entry of substances from the bloodstream into the brain to a greater extent than any other capillaries in the body.
However, some internal and external conditions can damage this tightly controlled barrier, which I cover in this story without going into scientific and technical details. I only focus on the factors related to our lifestyle choices.
Why do we need to protect it?
When this delicate barrier is compromised, harmful substances naturally restricted from entering the brain can pass through, potentially leading to undesirable health consequences manifesting as cognitive decline, neurological disorders, and mental health conditions.
In science, the risks are captured in a process called increased permeability, leading to the entry of harmful pathogens, toxins, and inflammatory molecules to infiltrate the brain.
This 2017 paper on the Neurobiology of Aging documented that increased blood-brain barrier permeability is associated with dementia and diabetes.
As this NIH book chapter informs,
Multiple sclerosis (MS) is an autoimmune disease of the CNS associated with demyelination of axons, eventually leading to neurodegeneration. MS exhibits many hallmarks of an autoimmune inflammatory disorder, including the blood-brain barrier breakdown.
The unintentional toxicity to the brain can result in neuroinflammation, neuronal damage, and an elevated risk of viral infections like encephalitis, neurological disorders like multiple sclerosis and Alzheimer’s disease, and mental health conditions like depression or schizophrenia.
How to Protect the Blood-Brain Barrier?
Any substance entering the bloodstream that is harmful to the brain’s chemistry and structure can be a risk factor for the blood-brain barrier (BBB). I cover them at a high level to create awareness.
1 —Refrain from Toxins, Chemicals, and Radiation
The neurotoxicology of BBB is well-studied. Chemical exposure can lead to brain inflammation, weakening the BBB and making it more permeable. Exposure to radiation from environmental and medical treatments can adversely impact the BBB.
For example, in cancer treatment, radiation therapy is used to target and destroy cancer cells. However, it can also affect nearby healthy tissues, including the BBB. Radiation therapy for brain tumors can weaken the BBB in the surrounding areas, potentially allowing harmful substances to enter the brain.
Toxins, chemicals, and radiation are harmful substances from various sources that can increase oxidative stress, inflammation, and cerebral blood flow. Some toxins can directly damage the BBB cells, making them more penetrable. They can also cause genetic mutations.
As documented in this paper, ionizing radiation can impair the integrity of BBB. Exposure to ionizing radiation from X-rays and CT scans can, in excessive amounts, damage the BBB. While these diagnostic tools are crucial for medical evaluation, excessive or unnecessary exposure should be minimized to protect the integrity of the BBB.
Some occupations, like radiologic technologists and nuclear workers, involve regular exposure to ionizing radiation. In rare cases, accidents involving radioactive materials or nuclear incidents can expose people to high levels of radiation. The critical point is that prolonged or high levels of radiation exposure in these jobs and accidents can threaten the BBB’s function and integrity.
Takeaway: We must be aware of environmental toxins, eat healthy foods, drink clean water, and use caution with medications and substances that may contain harmful toxins. We must limit exposure to unnecessary sources of radiation by following safety guidelines. We must also avoid harmful substances like drugs, smoking, and excessive alcohol use.
2 — Prevent Injuries and Infections
When we experience a head injury, it can directly damage the BBB’s cells, creating small holes in the protective barrier. This damage can increase the risk of harmful substances entering the brain where they shouldn’t be.
Infections can trigger an immune response in the brain, leading to inflammation. This inflammation, as I cover in the next section, can weaken the BBB’s defenses, making it more absorbent. Inflammation is the body’s way of trying to fight off invaders, but it can also inadvertently let them into the brain.
Takeaway: To address these issues, we must protect the brain from injuries by following safety measures. To protect the BBB from infections, we must practice good hygiene, get necessary vaccinations, and obtain medical support promptly when we suspect an infection.
3 — Lower Oxidative Stress and Chronic Inflammation
Oxidative stress indicates an imbalance between the production of free radicals and the body’s ability to counteract their harmful effects with its antioxidant molecules.
Exposure to environmental toxins, smoking, and unhealthy diets lacking antioxidants might increase oxidative stress and harm the BBB. Free radicals can damage the BBB cells, making them more permeable and allowing unwanted substances to enter the brain.
Inflammation is the body’s response to injury, infection, or other harmful stimuli. When inflammation becomes chronic and uncontrolled, it can negatively impact the BBB. During inflammation, the body releases signaling molecules (cytokines). They can make the BBB more permeable, allowing immune cells to enter the brain and potentially cause damage.
Takeaway: The optimal approach is to manage stress and lower inflammation with healthy lifestyle choices, therapies, and medication when required. Addressing allergies and autoimmune conditions is also necessary to protect BBB.
4 — Prevent Hypertension and Ischemia
Hypertension means high blood pressure. Prolonged high blood pressure can damage the delicate blood vessels of the brain. This damage can make the BBB more permeable, allowing substances from the bloodstream to enter the brain, which can potentially be harmful.
As documented in this 2022 paper in Nature, BBB damage in patients with hypertension is considered to be the main mechanism for the initiation and progression of cerebral small vessel disease and the development of forms mixed with neurodegeneration.
If we imagine the BBB as a flexible, muscular wall, high blood pressure is like constantly pushing against this protective wall. Over time, the wall can develop small cracks, allowing harmful substances from the outside to seep through.
Ischemia occurs when the blood supply to a particular part of the body, including the brain, is reduced. When the brain doesn’t receive enough blood and oxygen, as in a stroke, the cells in the affected area can become damaged and make it more penetrable.
This 2020 paper in the Current Neuropharmacology informs that the BBB can be disrupted by ischemic and hemorrhagic stroke, which can lead to an influx of water molecules and blood components into the brain's extracellular space, resulting in serious clinical consequences such as vasogenic brain edema and hemorrhagic transformation.
You can learn about the neuroinflammatory mechanisms of blood-brain barrier damage in ischemic stroke in this scientific paper in the American Journal of Physiology. You can learn about the effects of chronic hypertension on the blood-brain barrier in this paper in the Hypertension journal.
Takeaway: To protect the BBB from the effects of high blood pressure, we must manage hypertension with lifestyle changes like exercise, diet, rest, and sleep and in severe cases we need medication. To prevent ischemic events like strokes, we must maintain a healthy lifestyle and avoid harmful substances like drugs, smoking, and excessive alcohol use.
5 —Lower the Impact of Aging and Genetic Mutations
Like other bodily functions, aging can adversely affect the BBB. As we age, the BBB can experience changes that make it more vulnerable to disruption.
Over time, the cells that make up the BBB can become less efficient at maintaining the barrier’s integrity — the aging of the cerebral microcirculation results in a significant alteration in BBB.
As explained in a 2019 paper in the Journal of Neurochemistry, genetic mutations can potentially modify the structure and function of genes and proteins associated with the blood-brain barrier. These genetic alterations can be likened to a double-edged sword, as their effects on the BBB vary significantly.
While certain mutations may enhance the BBB’s protective capabilities, others, depending on the specific genetic changes involved, may compromise its integrity. Research in this field is still in its early stages, and scientists are continually gaining a better understanding of how genetic variations influence the BBB.
Takeaway: While we can’t stop aging, maintaining a healthy lifestyle can help slow the natural aging process and help us age gracefully. If we suspect a genetic mutation that might affect the BBB, we need to obtain genetic counseling to understand the potential risks and how to manage them. Focussing on activation of longevity genes can lower the risks of premature aging.
How About Medical and Health Sciences?
The blood-brain barrier (BBB) is crucial for protecting the brain and its neurons, but it can be disrupted during neurological diseases, leaving the brain vulnerable.
Scientists and clinicians know that neurological disorders are a leading cause of disability and death globally. As documented in this 2023 paper, however, drug delivery to the brain is challenging due to the BBB’s selective nature.
The paper informs that innovative methods are being developed to overcome this challenge, including using nanoparticles for drug delivery, gene therapies delivered by modified viruses, transporters for stroke treatments, intranasal delivery, cell therapies, and focused ultrasound with microbubbles.
Developing reliable BBB models for drug screening and understanding BBB dysfunction mechanisms is crucial for progress in treating neurological disorders, and significant studies are working on them. I will keep you updated in a review article.
Conclusions
Based on my years of studies, I see the blood-brain barrier (BBB) as a vital fortress protecting the brain from harmful substances while allowing essential molecules for cognitive function to pass through.
Understanding its anatomy, function, and vulnerabilities is essential for maintaining cognitive health and preventing associated disorders.
By learning about the intricacies of BBB permeability, we can uncover the potential risks posed by its compromise, ranging from cognitive decline to neurological and mental health conditions.
A proactive approach is essential to protecting the BBB and promoting brain health. Crucial steps include avoiding toxins, chemicals, and radiation and preventing injuries and infections.
Additionally, managing oxidative stress, chronic inflammation, hypertension, ischemia, the impact of aging, and genetic mutations can significantly contribute to maintaining BBB integrity.
Implementing these protective measures strengthens the BBB and supports brain health, promoting resilience against the myriad challenges posed by modern lifestyles.
Awareness, education, and proactive lifestyle choices are our most potent weapons in this journey. These approaches can empower us to protect our brain’s most vital guardian—the blood-brain barrier.
Thank you for reading my perspectives. I wish you a healthy and happy life.
If you found this story helpful, you may also check out my other articles on NewsBreak. As a postdoctoral researcher and executive consultant, I write about important life lessons based on my decades of research and experience in cognitive, metabolic, and mental health.