The Causes of Cognitive Decline

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Cognitive decline, including conditions like Alzheimer’s disease and dementia, has long been a subject of intense scientific research and public concern (as it should be). In the past, the main belief was that cognitive decline had a single cause or a simple linear progression. However, as our understanding of the brain has deepened, it has become increasingly clear that cognitive decline is a complex and multifactorial condition. Dr. Dale Bredesen’s groundbreaking work, in particular, has uncovered what many of these factors are. 

This paradigm shift challenges the traditional approach of targeting a single cause and offers new possibilities for a more comprehensive and personalized approach to prevention and treatment. This is what my 1:1 clients receive when we work together. 

In this blog post, we will dive into the intricate web of causes behind cognitive decline, dispelling the notion of a singular culprit and shedding light on the interplay of multiple factors. We will explore some of the key factors that have been involved in cognitive decline. From inflammation and nutrient deficiencies to hormone imbalances, suboptimal neurotrophic factor support, insulin resistance and sugar toxicity, toxins, and more, we will examine how these interconnected elements can significantly impact your brain health.

As we explore these factors together, I want to emphasize that not every person is affected by the same factors or even the same number of factors. We can’t rely on a one-size-fits-all solution anymore; instead, we must consider the unique combination of factors that may contribute to each person’s cognitive decline and tailor treatment approaches accordingly. Understanding this intricate web of potential causes empowers us to take the necessary steps to optimize brain health and mitigate the risk of cognitive decline. 

Let’s get started!

Inflammation: The Silent Culprit

In recent years, research has increasingly focused on the role of inflammation in cognitive decline. Traditionally associated with the body’s immune response to injury or infection, inflammation is now recognized as a potent contributor to various chronic diseases, including neurodegenerative conditions.

When the brain experiences insults such as infections, toxins, or cellular damage, the immune system initiates an inflammatory response as a protective mechanism. However, when inflammation becomes chronic and dysregulated, it can have detrimental effects on brain health. The persistent activation of immune cells and the release of pro-inflammatory molecules can disrupt normal brain function and lead to cognitive decline.

Pro-inflammatory molecules, such as cytokines and chemokines, can interfere with the communication between neurons, impair synaptic plasticity, and disrupt the formation of new memories. Inflammatory processes can also contribute to the formation of beta-amyloid plaques and neurofibrillary tangles, which are hallmark pathological features of Alzheimer’s disease.

Several lifestyle factors can contribute to chronic inflammation, including a sedentary lifestyle, poor diet, stress, and inadequate sleep. Obesity, metabolic syndrome, and conditions like diabetes are also associated with low-grade systemic inflammation, which further increases the risk of cognitive decline.

Addressing inflammation is a key aspect of preserving brain health. While helping the immune system re-regulate itself, it’s equally as important to discover what caused the inflammation in the first place. I guess you can say that inflammation isn’t a true cause, because it happens in response to something else (such as the sections below). However, the pathological process of chronic inflammation still plays a significant role in cognitive decline, which is why it’s included here.

Gut Dysfunction: The Gut-Brain Connection

The intricate connection between the gut and the brain goes beyond the gut microbiome (your gut bugs) and extends to the concept of gut dysfunction. Disruptions in gut health, including increased intestinal permeability (leaky gut), impaired digestion, and imbalances in the gut microbiome, have been implicated in cognitive decline and other neurodegenerative disorders.

Intestinal permeability, commonly known as “leaky gut,” refers to the impairment of the gut barrier function. The gut lining acts as a protective barrier, allowing the absorption of vital nutrients while preventing the entry of harmful substances. When the gut barrier becomes compromised, undigested food particles, toxins, and bacteria can leak into the bloodstream, triggering an immune response and body-wide inflammation.

Leaky gut can have far-reaching consequences on brain health. The increased permeability allows pro-inflammatory molecules to enter the bloodstream and cross the blood-brain barrier, promoting neuroinflammation and contributing to cognitive decline. Additionally, toxins and bacterial byproducts may directly affect brain function. How scary is that?

The gut microbiome is a diverse community of microorganisms living in your gastrointestinal tract that plays a vital role in maintaining overall health, including brain function. Disruptions in the balance of gut microbiome, known as dysbiosis, have been associated with cognitive decline.

The gut microbiome influences brain health through various mechanisms, such as the production of neurotransmitters (including serotonin), short-chain fatty acids (such as butyrate), and metabolites as well as modulating the immune system, influencing the activation of immune cells and the release of inflammatory molecules. Dysbiosis can lead to altered neurotransmitter levels, chronic low-grade inflammation, and oxidative stress, all of which can negatively impact cognitive function.

As much as you may not want to admit it, diet and lifestyle factors significantly influence gut health and, consequently, brain function. A diet high in processed foods, added sugars, and unhealthy fats disrupts the gut microbiome and increases intestinal permeability, contributing to gut dysfunction and cognitive decline.

Additionally, lifestyle factors such as chronic stress, lack of sleep, and sedentary behavior can negatively impact gut health, further exacerbating the issue. Hello, living in America! 

In short, maintaining gut health is essential for preserving cognitive function and promoting overall well-being. To learn more about strategies for nurturing your own gut health, check out this blog post.

Nutrient Deficiencies: Feeding the Brain

The saying “you are what you eat” holds true when it comes to brain health. Proper nutrition plays a vital role in supporting cognitive function and protecting against cognitive decline. Nutrient deficiencies have been identified as a potential contributor to cognitive decline, emphasizing the importance of providing the brain with the essential building blocks it needs to function properly and thrive.

While there are many nutrients that are needed for proper brain function, some of the key nutrients are the B vitamins, omega-3 fatty acids, vitamin D, magnesium, and zinc.

B vitamins, including folate, vitamin B12, and vitamin B6, play key roles in neurotransmitter production, DNA repair, and the maintenance of myelin, the protective coating around your nerve fibers. Folate and vitamin B12 deficiencies, in particular, are linked to elevated levels of homocysteine, an inflammatory amino acid associated with increased risk of cognitive decline. 

Omega-3 fatty acids, especially docosahexaenoic acid (DHA), are crucial for brain health. They are integral components of brain cell membranes and play a role in neuronal communication, synaptic plasticity, and reducing inflammation. 

Vitamin D receptors are found throughout the brain, including regions involved in memory and cognition. Low levels of vitamin D have been associated with cognitive decline, depression, and neurodegenerative disorders.

Magnesium plays an important role in regulating neurotransmitter function and synaptic plasticity. It also serves as the vehicle that drives energy molecules where they need to go – a good thing too, since the brain is one of the top energy users in the body.

Additionally, zinc is also involved in neurotransmission and synaptic plasticity. Deficiencies have been shown in many forms of brain dysfunction, including cognitive decline.

Hormone Imbalance: The Delicate Equilibrium

Hormones play a critical role in regulating various bodily functions, including brain function and cognition. Hormone imbalances, particularly in key hormones such as estrogen, progesterone, testosterone, and thyroid hormones, can have a profound impact on cognitive health. Understanding the delicate equilibrium of hormones and their role in brain function is complex, yet essential for addressing and preventing cognitive decline.

Diving a little deeper, estrogen supports neuronal growth, synaptic plasticity, and neurotransmitter activity, while progesterone has neuroprotective and anti-inflammatory effects.

This is especially important to understand when it comes to menopause and perimenopause, when estrogen and progesterone levels decline. During this time period, women may experience cognitive changes such as memory problems, difficulty concentrating, and mood fluctuations. Similarly, hormonal fluctuations during the menstrual cycle can impact cognitive function in premenopausal women.

Testosterone also plays a vital role in brain function for both men and women. Testosterone influences cognition, mood, and spatial ability. In men, declining testosterone levels with age have been associated with cognitive decline and an increased risk of neurodegenerative disorders.

Thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3), are also critical for regulating metabolism, energy production, and brain function. Thyroid hormone imbalances, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid), can thus impact cognitive function. Hypothyroidism is associated with symptoms such as fatigue, poor concentration, and memory problems, while hyperthyroidism can lead to irritability, anxiety, and difficulty focusing.

Perhaps the hormone I see imbalances in most often is the stress hormone, cortisol. The stress response involves the release of hormones, such as cortisol and adrenaline, which prepare the body for fight or flight. However, chronic stress and prolonged elevation of cortisol can have detrimental effects on cognitive function.

The high cortisol levels associated with chronic stress can impair memory, attention, and decision-making abilities. Not to mention, it pulls resources from making the other hormones we’ve already discussed, which can contribute to imbalances in those hormones. The body always prioritizes short-term over long-term survival (how else would you get to the long-term if you didn’t survive the short-term?).

In essence, hormone imbalance can significantly influence brain function and contribute to cognitive decline. Understanding the delicate equilibrium between them and addressing imbalances through hormone replacement therapy or other interventions, when necessary, can help support brain function and potentially reduce the risk of cognitive decline. 

Suboptimal Neurotrophic Factor Support: Nurturing Brain Connections

Neurotrophic factors are a group of proteins that play a crucial role in the growth, development, and maintenance of brain cells and their connections. These factors support neuronal survival, promote the formation of new synapses, and enhance synaptic plasticity. Insufficient or imbalanced neurotrophic factor support can hinder brain health and contribute to cognitive decline. 

Brain-Derived Neurotrophic Factor (BDNF) is one of the most well-known and studied neurotrophic factors. It is involved in the growth and survival of neurons, as well as the formation and strengthening of synapses. BDNF supports the growth of new neurons, a process known as neurogenesis, particularly in the hippocampus, a brain region critical for learning and memory (and usually the first region affected by Alzheimer’s Disease). Research suggests that reduced levels of BDNF are associated with cognitive decline and an increased risk of neurodegenerative disorders such as Alzheimer’s disease.

Insulin Resistance: A Link to Brain Fog

Insulin is primarily known for influencing the uptake and utilization of glucose. However, it also plays a vital role in the brain. Insulin receptors are present throughout the brain, including areas responsible for learning, memory, and cognition. Insulin helps regulate neurotransmitter levels, supports synaptic plasticity, and enhances neuronal survival and function.

In cases of insulin resistance, when cells become less responsive to insulin, glucose uptake in the brain may be impaired. Because these cells have been overloaded with glucose for long, they also lose the ability to utilize fat as fuel. This can lead to reduced energy availability and compromised brain function.

Insulin resistance is closely linked to chronically elevated blood sugar levels, known as hyperglycemia. Prolonged hyperglycemia can contribute to oxidative stress, inflammation, and the formation of advanced glycation end products (AGEs) in the brain. These processes can damage neurons, impair synaptic function, and accelerate cognitive decline.

Additionally, hyperglycemia can promote the accumulation of beta-amyloid plaques, a hallmark of Alzheimer’s disease. These plaques interfere with neuronal communication and contribute to cognitive impairments.

Studies have shown that individuals with insulin resistance are more likely to experience cognitive impairments, including memory problems, decreased attention span, and reduced executive function. Insulin resistance has also been associated with structural and functional changes in the brain, including reduced brain volume and altered connectivity. Yikes!

Sugar Toxicity: Sweet Saboteur

Sugar is an ubiquitous ingredient in the Standard America Diet (yes, that spells sad), found in a variety of processed foods and beverages. While our brains require glucose for energy, excessive consumption of refined sugar (and foods that rapidly bread down into sugar) can have detrimental effects on cognitive health. Excessive sugar consumption can lead to inflammation, oxidative stress, insulin resistance, and impaired neuroplasticity, all of which contribute to cognitive decline.

In fact, high sugar intake has been associated with various cognitive impairments and an increased risk of neurodegenerative disorders, including Alzheimer’s disease. Research even suggests that chronic consumption of sugary beverages and a high-glycemic diet (the Standard American Diet) is associated with lower cognitive performance, reduced hippocampal volume, and an increased risk of cognitive decline.

Additionally, excessive sugar consumption can contribute to mood fluctuations, increased anxiety, and decreased overall mental well-being. These effects can further impact cognitive function and quality of life.

Toxins: Unseen Threats

In our modern world, we are exposed to a variety of toxins on a daily basis. These toxins can come from our environment, mold toxins, heavy metals, and other sources. While the immediate effects of toxin exposure may or may not be evident, their long-term impact on cognitive health is an area of growing concern. 

Environmental toxins are substances found in the air, water, soil, and various consumer products. They include things such as pesticides, air pollutants, industrial chemicals, and toxic metals. These toxins can enter our bodies through breathing them in, swallowing them, and even skin contact. Prolonged or repeated exposure to these toxins can lead to chronic inflammation, oxidative stress, and damage to brain cells.

Mold is a type of fungi that can grow in damp and poorly ventilated areas of buildings and even on food (grains are the biggest culprit). When mold spores are inhaled or come into contact with the body, they can release toxins known as mycotoxins. Mycotoxins have been associated with a range of health problems, including respiratory issues and neurological symptoms.

Research suggests that exposure to mold toxins may contribute to cognitive impairment, memory problems, and difficulty with concentration and focus. They activate the innate immune system causing inflammation and oxidative stress.

Heavy metals, including lead, mercury, arsenic, and cadmium, are toxic substances that can accumulate in the body over time. Sources of heavy metal exposure include contaminated amalgam dental fillings, water, certain foods, air pollution, and occupational hazards.

Heavy metals have been shown to have neurotoxic effects, damaging brain cells and impairing cognitive function. They can disrupt neurotransmitter function, interfere with synaptic transmission, and contribute to oxidative stress and inflammation in the brain. Do you see a pattern here?

Oxidative Stress: Balancing the Scales

I’ve mentioned this term a few times now, so let’s dive into what it means. Oxidative stress occurs when there is an imbalance between the production of free radicals and the body’s ability to neutralize them with antioxidants. Free radicals are highly reactive molecules that can cause damage to cells, including those in the brain, leading to malfunctioning neurons and impaired synaptic transmission. The cumulative effects of oxidative stress have been implicated in various health conditions, including cognitive decline and the aging process. 

But where do these free radicals come from? Normal metabolic processes, such as energy production, in the body generate free radicals as byproducts. While the body has built-in antioxidant defense mechanisms, excessive oxidative stress can overwhelm these defenses.

Chronic inflammation, whether triggered by infections, autoimmune conditions, or lifestyle factors, can also generate free radicals and contribute to oxidative stress. In turn, oxidative stress can further exacerbate inflammation, creating a vicious cycle.

Exposure to environmental pollutants, toxins, radiation, and certain chemicals can increase oxidative stress in the body. As well as unhealthy lifestyle habits, such as a poor diet, sedentary behavior, smoking, excessive alcohol consumption, and chronic stress, can contribute to oxidative stress. 

Pathogens: The Bad Guys

Pathogens refer to microorganisms, such as bacteria, viruses, fungi, and parasites, that can invade our bodies and cause infections. While our immune system works hard to combat these invaders, certain pathogens have the ability to target and affect the brain, leading to cognitive impairment. 

Some viruses have been associated with cognitive decline and neurological symptoms. For example, the herpes simplex virus (HSV) has been linked to cognitive impairment, particularly in older adults. Other virus that have been known to affect the brain include Epstein Barr virus (EBV) and COVID-19. 

Certain bacterial infections can also have negative implications for cognitive health. For instance, Lyme disease, caused by the bacterium Borrelia burgdorferi transmitted through tick bites (as well as many associated co-infections), can lead to cognitive impairments, including memory problems, difficulty concentrating, and brain fog. The bacteria can invade the central nervous system and cause inflammation, contributing to cognitive dysfunction.

Fungal infections and parasites, although less common, can also impact cognitive health. 

As you can see, cognitive decline is a very complex and multifactorial process that can be influenced by many factors. In this post, we have explored some of the key contributors to cognitive decline, including inflammation, nutrient deficiencies, hormone imbalance, suboptimal neurotrophic factor support, insulin resistance and sugar toxicity, toxins, oxidative stress, and pathogens.

However, it’s important to recognize that there is no single cause of cognitive decline. Rather, it is often the result of a combination of these factors, each impacting the brain in its own way. This understanding stresses the importance of taking a comprehensive and personalized approach to cognitive health.

Taking proactive steps to support brain health is essential at any stage of life. This includes adopting a healthy lifestyle that incorporates a balanced diet, regular physical activity, stress management, quality sleep, and engaging in cognitive activities. Additionally, working with someone like me, who specializes in brain health and Dr. Bredesen’s approach to cognitive decline, can provide valuable guidance and individualized strategies that help maximize your success.

Remember, everyone’s journey to optimal brain health is unique. What works for one person may not work for another. That’s why it is important to approach cognitive health with an open mind and a willingness to explore different avenues.

By understanding the complex interplay of factors that contribute to cognitive decline and taking proactive steps to address them, we can empower ourselves to maintain and enhance our cognitive abilities throughout life!

To learn more, check out these links.

• The truth behind amyloid
• My approach to preventing and reversing cognitive decline
• My story
• The First Survivors of Alzheimer’s

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