How Does Chronic Stress Accelerate Neurodegenerative Disorders?
The kicker is… Chronic stress ISN’T the ONLY factor that we have to take into consideration!
The current problem that we are facing with Alzheimer’s disease is that the number of people who are currently afflicted with Alzheimer’s is on the rise. As the Alzheimer’s Association in the United States of America mentions,
More than 5 million Americans are living with Alzheimer’s. By 2050, this number is projected to rise to nearly 14 million.
The National Institute of Aging also has this comment about Alzheimer’s:
Alzheimer’s disease is currently ranked as the sixth leading cause of death in the United States, but recent estimates indicate that the disorder may rank third, just behind heart disease and cancer, as a cause of death for older people.
Alzheimer’s is the most common cause of dementia among older adults. Dementia is the loss of cognitive functioning — thinking, remembering, and reasoning — and behavioral abilities to such an extent that it interferes with a person’s daily life and activities. Dementia ranges in severity from the mildest stage, when it is just beginning to affect a person’s functioning, to the most severe stage, when the person must depend completely on others for basic activities of daily living.
Alzheimer’s disease is a big problem to us. It can affect us when we see our loved ones on the decline, to the point where we look like complete strangers to them, just because they cannot even remember who we are! My grandmother had more pronounced symptoms of dementia in the last few years of her life, to the point where she was unable to take care of herself properly or even remember who I was.
But of course, being a young and foolish teenager back in those days, I had no idea how big of a problem it was, except for the “loss of cognitive functioning” — especially when she was becoming so forgetful that it was frustrating to talk to her.
The problem is, the mechanism behind how Alzheimer’s develops is extremely complicated.
That’s why nobody has the answer as to how to cure or prevent Alzheimer’s from developing — they’d be overnight billionaires otherwise.
But there are a few recurring themes that appear:
- Alzheimer’s is related to inflammation in the brain.
- People who develop Alzheimer’s don’t usually develop Alzheimer’s on its own — there is a combination of other inflammatory disorders such as Type 2 diabetes or heart disease. Alzheimer’s usually appears as at a later stage — but it is more or less inevitable.
The thing is, how do we piece the mechanism as a coherent whole to understand it better?
From the recurring themes involved, we do know that brain inflammation plays a significant role in the development of Alzheimer’s. There is also a link between brain inflammation and neuron cell death, especially when an increased level of pro-inflammatory cytokines such as tumour necrosis factor alpha (TNF-α) in the brain can induce the neurons in the brain to undergo apoptosis (commit suicide).
A neuron in our brain “is the basic working unit of the brain, a specialized cell designed to transmit information to other nerve cells, muscle, or gland cells.” It is also the case that “neurons stop reproducing shortly after birth. Generally, when neurons die they are not replaced, although neurogenesis, or the formation of new nerve cells, does occur in some parts of the brain.”
Therefore, if there is a sufficent inflammatory signal intensity to induce sufficient neuronal apoptosis to a point where our cognitive functions take a hit — we’d have the symptoms of degenerative dementia staring at us directly in the face, no?
But the brain is well protected! How do we link diabetes with Alzheimer’s?
Our brain is well insulated from the rest of the body via this protective filter known as the blood-brain barrier (BBB). The BBB is described by this article as:
The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood–brain barrier, which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and also protects the neural tissue from toxins and pathogens, and alterations of these barrier properties are an important component of pathology and progression of different neurological diseases.
The BBB provides the brain an excellent level of protection from toxins and pathogens. We don’t want some pesky infectious virus or bacteria to enter our body during an infection and outright kill off the neurons in our brain that easily, do we? Hence the BBB provides that layer of defence against such critters. It also regulates the movement of different molecules between the blood and the brain — some molecules are allowed to sneak through the BBB, while others don’t.
Unfortunately, defences don’t last long if we keep on pulverising or attacking them, do they? Much like how a person wielding an axe can fell a tree with repeated chopping motions against the tree trunk, so can our BBB be felled.
Our BBB can be felled by pro-inflammatory cytokines. Both TNF-α and interleukin 1-beta (IL-1β) are known to increase the permeability of the BBB — meaning that the filtering capability of the BBB is reduced. Any noxious components in the blood that would have been kept out of the brain with a well functioning BBB can be let into the brain with a malfunctioning BBB, which can then trigger the microglial cells in the brain to produce more of the pro-inflammatory cytokines that then induce neuronal apoptosis.
As Type 2 diabetes is a chronic inflammatory condition where an elevated concentration of pro-inflammatory cytokines in the blood such as TNF-α and IL-1β signals the cells in the body to resist insulin signalling, the elevated concentration of these cytokines will also eventually weaken the BBB.
And that’s how a person can get develop a combination of Type 2 diabetes with Alzheimer’s!
How does chronic stress fit into this mechanism?
In Four Ways That Our Lifestyle Affects Our Immune System, I do explain how poor stress management and sleep deprivation can contribute to the adrenal glands releasing elevated amounts of the epinephrine (adrenaline) and norepinephrine (noradrenaline) hormones into our blood. These hormones are responsible for the fight-or-flight response that we do experience in times of stress. These hormones are also able to activate the pro-inflammatory nuclear factor kappa B (NF-κB) pathway in our body’s cells, which then start to produce more pro-inflammatory cytokines than necessary.
With chronic stress, we will find it difficult to sleep properly, and that amplifies the problem further in a vicious feedback loop, which ultimately results in the development of a chronic inflammatory problem in our body.
Unfortunately, chronic inflammation isn’t one of the key visible considerations, because we can’t really visualise the symptoms of chronic inflammation.
What we can visualise in chronic stress, though:
- Anxiety and panic attacks. This was shown to occur more readily in people who were administered epinephrine doses.
- A problem with sleep issues, as mentioned earlier.
- Epinephrine can also reduce blood flow to the digestive system, which can slow down or completely inhibit food digestion. Hence one’s appetite will also be significantly affected.
- Repeated anxiety/panic attacks can lead on into post traumatic stress disorder (PTSD).
When all these are happening, the most common response would be to seek therapy for all these mental health issues that one is facing, while the chronic inflammation that is raging on behind the scenes isn’t that well considered.
Unfortunately, though, war veterans who were diagnosed with PTSD are twice more likely to develop dementia than those who did not have PTSD!
Therefore, we do need to have proper stress relief outlets.
There are a few internal biochemicals that function as stress regulators.
For example, serotonin functions as a happy chemical in our brain that can provide a balance to depression and anxiety.
When we’re not releasing our stress properly, and we go for the wrong choices in life, though, other issues may arise, such as addictions, where we are fuelled by dopamine rushes to the brain as relief outlets.
The wrong choices in life may include an overconsumption of alcohol, which isn’t good for us. Neither does a binge on refined carbohydrates and processed sugary foods help us in the long run either, because excess alcohol or refined sugar consumption can result in the production of excess aldehydes in our blood, which can further contribute to and amplify the inflammatory problem that one is already experiencing from the chronic stress situation.
In other words: we can be eating or drinking ourselves to further harm in the years to come.
Eating right is one of the oft-overlooked facets of stress relief. We may crave comfort foods such as ice cream as a short term relief, but an addiction to ice cream may only accelerate one’s mental health decline more rapidly.
Ultimately, in conclusion…
Chronic stress can upregulate the pro-inflammatory signalling intensity in our bodies, which can lead on to the development of unwanted chronic conditions such as PTSD or Type 2 diabetes, which can further on into Alzheimer’s or other neurodegenerative disorders if left unchecked. But that isn’t the only contributor to the pro-inflammatory signalling dysregulation in a person’s body — other issues such as oxidative stress and autoimmune disorders can further exacerbate the situation of inflammation dysregulation in one’s body.
These problems can contribute to wreak severe havoc on one’s immune system functions. Is that why, then, that an Alzheimer’s patient may be at higher risk of death from a COVID-19 infection, since they have a compromised immune system?
What we feed ourselves (and our brains with) do play an important role with how we can properly manage stressful situations in life!
Do check out the 12 different nutrients (but not necessarily limited to these 12) that can support a healthy brain function. Writing this story was fuelled and supported by most of those nutrients.
Joel Yong, PhD, is a biochemical engineer/scientist, an educator and a writer. He has authored 4 ebooks (available on Amazon.com in Kindle format) and co-authored 6 journal articles in internationally peer-reviewed scientific journals. His main focus is on finding out the fundamentals of biochemical mechanisms in the body that the doctors don’t educate the lay people about, and will then proceed to deconstruct them for your understanding — as an educator should.
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