Understanding Immunosenescence, Age-Related Changes and Cognitive Health
Hello, I am Julie Donaldson and I am a clinical nutritionist with functional health training. I specialize in restoring balance in complex, chronic and acute health conditions. I welcome you to peruse other articles that may be of interest to you in your health investigation!
“So much of my mother’s health (illness) over her life seemed “benign” according to medical standards. But she developed Alzheimer’s disease in spite of being healthy by those standards. When we met and worked with Julie, the shadows behind the curtain began to show and we now understand how to protect our own family from “inheriting” this disease. ”
Brand new research is showing us how the immune system and its process of senescence is impacting cognitive health and the potential for development of dementia-type diseases.
People are living longer, but the immune system doesn’t stay the same throughout life. Immune senescence is the gradual remodeling of the body’s defenses with age.
These changes can affect how the body responds to infections and vaccines. They can also occur alongside inflammaging, the term for persistent, low-grade inflammation that becomes more common with age.
Understanding the biology can help you make sense of common age-related changes without assuming that age alone predicts your health. Healthy habits and personally-targeted care can support immune health over time. We now know that immune stresses earlier in life remodel how the immune system shifts throughout all stages of life. Early immune developmental experiences are shown to “set the stage” for vulnerability in later life. Prenatal experiences for the fetus being “imprinted” may also have lasting effects on physiology. This makes the importance of good, holistic functional health care from early on very pertinent.
We’ll cover more about the specific research findings related to the brain, but first let’s talk about immunosenescence - what it is, why we should care about it, and how you can minimize its effects, saving time and money while staying out of the doctor’s office.
How immunosenescence reshapes the body’s defenses
Immunosenescence occurs with gradual shifts beginning in middle age. Immune aging affects many parts of the body’s defense system over time. The pattern varies between people, with health conditions, medications, and past infections all playing a role. Age alone doesn’t predict how well you’ll respond to an immune challenge.
Senescent cells in the body basically expire after reaching their maximum replicative limits. Reduction in telomere length, DNA damage and oxidative stress can all affect this limit. Senescent cells release inflammatory signals - and of course the greater the number of senescent cells vs. active immune cells (which fight invaders), the lower the immune capacity.
Immune senescence differs from cellular senescence, when a damaged or stressed cell stops dividing but remains active.
Innate and adaptive immunities
There are 2 main systems within the body’s immune system. Innate immunity provides fast, broad defenses. Phagocytes, including macrophages, help find and remove germs, while natural killer cells attack infected or abnormal cells. With age, some of these cells may respond less effectively or communicate differently with other immune cells.
Adaptive immunity relies on T cells and B cells to target specific threats. The Th1 and Th2 cell balance within T cell differentiation needs to function like a teeter totter that spends more time in balance than stuck in a raised or lowered position. Age-related changes can make it harder to recognize unfamiliar pathogens, coordinate a response, or produce a strong set of antibodies. Immune memory still helps, but the response may differ by person and by threat.
Thymic changes can narrow the supply of new T cells. The thymus helps T cells, especially the naïve T cells that can respond to threats the body hasn’t met before. As the thymus shrinks with age in a process called thymic involution, it generally produces fewer of these new cells.
Most of us remember the teeter-totter from childhood - fun riding up and down, barely paying attention to the balance in between! The immune system does this also, but its two arms need more time in balance. These two arms are the Th1 and Th2 cell responses. Adaptive immunity relies on T cells and B cells to target specific threats. Age-related changes can make it harder to recognize unfamiliar pathogens, coordinate a response, or produce a strong set of antibodies. Immune memory still helps, but the response may differ by person and by threat.
Thymic changes can narrow the supply of new T cells.
The thymus helps mature T cells, especially the naïve T cells that can respond to threats the body hasn’t met before. As the thymus shrinks with age, a process called thymic involution, it generally produces fewer of these new cells.
Why does immunosenescence matter
Adults whose immunosenescence begins earlier or more significantly may face greater risks from infections, major diseases and vaccines, especially if they have had early life immune stresses - whether acute, repetitive or chronic. Senescent cells which produce inflammatory compounds can create more severe responses to both disease and vaccination.
The immune response to vaccination can vary with age and vaccine type. Reduced immune surveillance may affect outcomes as well. Immune surveillance is the immune system’s role in finding and responding to infected or abnormal cells.
Immune senescence, inflammaging, and daily exposures
Inflammaging refers to ongoing, low-level inflammation that can occur without an active infection or injury. Unlike short-term inflammation which helps the body respond to harm, chronic inflammatory signals may persist over time. Franceschi and colleagues introduced the term “inflamm-aging” in 2000, as discussed in this review of immunity and aging.
Weakened responses and excess inflammation can exist at the same time. This mix is one reason immune aging doesn’t fit a simple pattern of the whole system becoming less active.
Chronic conditions and toxic exposures compound immune changes.
The challenge of inappropriate immune cells reaching the brain
While all disease manifestations are challenging and often life-altering, perhaps Alzheimers disease (AD) and associated dementia-type diseases are the most challenging of all. Symptoms don’t appear in the initial years of disease development, and to date, there is no cure for these diseases. Some of our other major diseases can sometimes be successfully treated to prevent them from becoming terminal, but AD is currently not in that category.
And so, the new research highlighting a deeper look at the presence of monocytes in the brain is both concerning and illuminating.
We have known in the past that monocytes could enter the brain. Monocytes are important immune cells which provide a “first line of defense” against pathogens. But they are not originally brain-resident and thus, when they invade the brain they create inflammatory responses.
What is surfacing in the new research is the discovery that monocytes are taking over where senescent glial cells in the brain are dying. As monocytes exit the blood circulation, they turn into macrophages which are basically little Pac Men now scavenging on substances in the brain. The extent to which they replace glial cells is very broad in susceptible individuals.
Remember, we’ve discussed susceptibility in terms of the following:
prenatal and/or early childhood immune stresses
unresolved and/or acute or repetitive infectious stresses
vaccine reactions
toxins and leaky gut pathogens
In order to prevent this unnatural and unwanted change in brain cells, it is necessary to track and support abnormal immune responses through life, as well as to support the body with proper individualized nutrition, detox and healthy mind & spirit routines. It is documented that only 30 minutes of mental stress equals damage to the integrity of the gut barrier - something that is crucial for maintaining immune health, especially in the gut..
Autophagy, immunosenescence and brain health
Autophagy is a big piece of the puzzle here. Autophagy is the normal, healthy process of cell death and new cell creation. We’ve covered the brain, autophagy and immunity in detail before, here and here.
Keeping microglia out of senescence requires autophagy. Autophagy is inhibited by inflammation and by vitamin D deficiency or low VDR reception. If the momentum moves in this direction, you’ll lose glial cells.
Another key factor in autophagy is having healthy mitochondria and mitophagy. These both require all the things we speak about regularly at True Nature. The mitochondria are our energy-creators - little engines inside the cells which complete the final stage of ATP production where energy is generated.
Without autophagy, what occurs is cell exhaustion. Cell exhaustion is worse than cellular senescence, as it is irreversible.
The gut microbiome is a promising area of research
Gut microbes interact with the immune system and may influence inflammation. Researchers are studying how changes in the microbiome relate to immune aging, but the findings are still developing. A consistent finding is that in people over 60 years of age, populations of bifidobacteria have been observed to decrease markedly, leading to a reduction in the inhibition of the growth of some pathogens and potentially an increase in the susceptibility to infections.
Of course we know that the gut comprises about 70% of the body’s immune system, so it only stands to reason that keeping the gut in good balance is going to support better immunity over the decades.
How we assess immunosenescence
In both clinical investigation and in research, immune aging may be assessed by looking at immune-cell subtypes, antibody responses, or inflammatory markers. These measures can help describe parts of the immune system, but their meaning depends on a person’s overall health and daily practices. No single biomarkers captures the immune system - it is complex and individual in the way it expresses.
A lab result may reflect one part of a complex process and can widely vary between people.
A clinician can investigate history, recurrent or severe infections & vaccine reactions and place them alongside test results to determine how efficiently the immune system is likely to be working. Many, many people cannot feel the accumulation of the standard, chronic low-grade stresses, which makes regular testing. investigating and balancing so important.
Summation and solutions - practical ways to support immune health with age
Immunosenescence is a natural progression in the aging immune system. It is not, however, solely affected by aging. Early life immune experiences, infections, vaccine reactions, DNA damage, telomere shortening and oxidative stress from pathogens, toxins and stress all affect the extent and form taken in immunosenescence. Protecting all of the above from chronic & severe conditions allows the body to age appropriately and effectively, continuing to deliver resources for immune performance. In light of new research, we understand that both chronic & severe conditions can allow a contributing factor to Alzheimer's disease previously unknown - and that is the infiltration of monocytes into the brain. These immune cells incite inflammation and replace normal glial (brain) cells.
Prioritize sleep, regular physical activity, and healthy, personalized nutrition. There is no one-size-fits-all approach to nutrition that is effective for everyone.
Maintain periodic lab testing, clinical evaluation and assessment of T cell functions. Vitamin D testing is particularly crucial and should include both forms of D (active & stored), as each level informs us in different ways.
Practice regular detox methods catered to your own body, including glymphatic cleansing.
Practice mindfulness & emotional processing to maintain low stress levels.
Assure the best possible gut health for yourself, inclusive of assessment with stool testing.
Smart, personally-designed, sustainable habits matter more than promises of a quick fix - always! If you are in need of personalizing your health care approaches, please contact me at Julie@truenaturehealthconsulting.com. We provide holistic telehealth services.