We all carry an anecdote to share about how stress is affecting our sleep patterns, making us feel irritable, moody or even neglected at times. But, apart from all these oddities we face day in and day out, do you know how stress has been slowly eating away your brain?
Stress happens to all of us, but it isn’t always that bad. For example, a wee bit of stress can give you a motivation to present a compelling speech at a public event, or help you focus while playing a competitive sport.
There is also this other kind of stress, a bad one, that sustains over a length of time called chronic stress. This type hammers you daily, and eventuates when you’re in situations like having a heated argument with our closed ones, when you overwork or when you’re at risk of losing your job.
This low-key stress can trigger the release of all sorts of hormones that can wreak havoc on our physiological functioning. They can give you racing heart, shallow breathing, muscle tension and even slow down the digestive process.
In fact, these physiological responses are actually part of our survival mechanism called the ‘fight or flight’ response (also known as the acute stress response) that lets us decide whether we stay and deal with a dangerous situation or to run away to safety. However, when the stress gets chronic and our immune system activates this response too often, it takes its toll on us.
How Stress Affects The Brain
Chronic stress affects the overall structure of the brain, including size, and its functionality. The damage is discernible right down to the level of genes.
Stress originates from the hypothalamic pituitary adrenal (HPA) axis. The HPA axis is our central stress response unit slathered with a series of intertwined channels that connect the brain and the endocrine system.
During a stressful situation, the brain signals our HPA axis to release a hormone called cortisol, which procures glucose and fatty acids from the liver to prime your body with the energy required to face challenges lying ahead.
However, if the HPA axis keeps secreting cortisol for an extended period, the elevated levels of cortisol can inflict damage to your brain.
For example, when you’re under stress, the activity and synaptic connections in the amygdala, the part of the brain that induces aggression or fear, increase. And as the levels of cortisol continue to rise, the electrical rhythms in the hippocampus, the part of the brain’s limbic system associated with emotion, learning, memories formation, and stress control, get disturbed which in turn deteriorate its performance.
The hippocampus also suppresses the activity of the HPA axis. Enfeeblement of the HPA axis would lead to your ability to cope with stress being compromised. Furthermore, surge in cortisol levels can cause your brain to literally shrink in size as a result of loss of synapses between neurons; it can also cause your prefrontal cortex (or PFC) to shrink.
The prefrontal cortex covers the front part of the brain. This region of the brain has been implicated in making executive functions, which include things like concentration, self-control, decision-making, social interaction and problem-solving.
Shrinkage in the prefrontal cortex means you won’t be as proficient in carrying out certain tasks as you were. The damage doesn’t end here, though. Chronically high levels of cortisol have also been shown to slow down the process of neurogenesis – making of new neurons – in the hippocampus.
So it’s evident that if fewer cells are being made in the hippocampus, you would be going through a rough patch trying to learn new skills or remember things. Also, even worse, chronic stress has been shown to accelerate the onset of serious mental disorders like depression, Alzheimer’s and other related forms of dementia.
The Effect of Stress On Your Genes
The effects of stress go right down to the brain’s DNA. Or, let’s say – your childhood experiences, or how you were raised – can influence changes in your brains down to the level of genetics.
A study at Salk Institute for Biological Studies in 2018 showed that the amount of care a mouse pup receives from its mother plays a substantial role on how effectively the pup copes with stress later in adulthood.
The offspring of more-attentive mice grew up to be calm adults because their brains developed more cortisol receptors, hence were less sensitive to stressful situations. And the pups raised by less-attentive mice grew up to be more sensitive to stress throughout life.
This dissimilarity in offspring raised by different mothers is not at all genetics, it’s epigenetics, meaning no change in genetic code is involved although the upbringing alters the way the genes are expressed.
The experiment also found that these epigenetic changes can be reversed when moms are swapped. A week of nurturing is all it takes for the mother mouse to establish these changes in pup’s epigenomes. Surprisingly these epigenetic changes can be passed down through generations, they found.
Stress isn’t inherently evil. It has been wired with us since the dawn of our evolution. But if you ever feel like you’re being overpowered by these ruthless pressures of life, set up a strategy to subdue your stress, before it subdues you.
There are many ways to deal with stress. Of those, the most effective are exercise and meditation. These two inventions have been shown to reverse the effect of cortisol on the stressed brain and eventually invigorates the full functionality of the hippocampus, thus improving your memory in the process. Spending time in nature, listening to music, and laughing out loud just about have the same effect.