THE GOOD, THE BAD AND THE UGLY

HOW STRESS EVOLVED: THE ORIGIN OF A MODERN PLAGUE

Ever heard of Walter Cannon? Most people haven’t. He’s the guy responsible for your stress! In 1915, he coined the term “stress” in connection with his research on flight-fight responses. Prior to the 1950s, stress was not regularly used as a scientific term.
There is no doubt that today the word “stress” is ubiquitous in our lexicon. “How are you?” you ask. The statement “I’m stressed” is common. As your blood pressure rises listening to their woes, you probably wish you hadn’t asked.

THE HIDDEN REASON BEHIND YOUR STRESS

Even though stress theory is a relatively new development, people have dealt with it since the beginning of time. The evolution of stress responses was driven by some short-term selective advantages (flight/fight).

Our survival would not have been possible without this response. In the past, our ancestors provided protein for predators. Oh, how things have changed. But, a few of them got away and survived long enough to reproduce and pass their genes along.
By learning from history, here we are today. The amygdala, located in the limbic system of the brain, has a crucial role in our survival. In addition to regulating emotion and memory, the amygdala is also responsible for responding to fight or flight situations. Similar to air surveillance radar, it is constantly active and monitors potential dangers. An incoming metaphorical missile sets alarm bells ringing.

In response to a threat such as being chased by a predator or being hit by a fast-approaching vehicle, the amygdala has a quick chat with our adrenal glands to produce glucocorticoids. In this process, our hypothalamus activates the sympathetic nervous system and prepares us for action. Thankfully, there are no predators roaming about, but we have replaced predators with modern-day stressors. In order to survive, society has evolved into other “must-have” essentials. Today, many of us have concerns about our financial security, relationships, health problems, and other issues that are associated with life in the modern world. These are the modern-day predators.

Physical challenges have joined by psychological factors, like believing that something will negatively affect you. In addition, we have evolved to focus on bad news because of our negativity bias.

WHAT IF I TOLD YOU STRESS IS IMPACTING YOUR GENES?

Ever heard of epigenetics? Don’t worry, you’re not alone. Think of two types of genes. Those that are hardwired and determine your height, the colour of your hair and eyes etc. Genes can also be soft-wired, which describes how environments and behaviours affect their functioning. This is called epigenetics. Epigenetic changes, unlike genetic changes, are reversible and do not change the DNA sequence, but they can change how your body reads the DNA sequence.

Exposure to chronic stress can alter gene expression to turn genes on and off. As an example, epigenetic modifications to BDNF (brain-derived neurotrophic factor) as a result of stress or trauma can be passed from parent to child. BDNF deficiencies increase the risk of anxiety disorders and can affect hippocampal function which impacts learning and memory. In an experiment, male mice were exposed to the scent of acetophenone (smells like cherry blossoms) while receiving a mild electric shock. They became afraid as a result.

When the male sperm of these mice was impregnated into female mice, the pups had an adverse reaction to acetophenone despite having never encountered it before. Likewise, their grandpas shared the same traits. These changes can last for three generations. Perhaps your great-grandparents passed on stress or other behaviours to you!

Having read that stress in the present can affect your future children, it isn’t surprising that stress in utero can also affect the unborn child. Depending on how the mother reacts to stress, her experiences during pregnancy can impact her baby’s developing brain. If the mother is in a highly dysregulated state, cortisol passing through the placenta in utero will negatively impact whatever structures are evolving. Therefore, the child may develop stress dysregulation in later life as a result of difficult experiences. Furthermore, a uterus’ blood flow can be restricted under stress, resulting in a foetus receiving fewer nutrients, hence causing a lower birth weight. Researchers found that babies with mothers who were stressed in the womb had IQs that were lower than average at 18 months compared to babies who were not stressed.

STRESS CAN BE GOOD FOR YOU – WHO KNEW?

There is a lot of truth to the saying “mind over matter”! Feeling stressed is directly related to how we perceive it. The power of the right mindset cannot be overstated. People who experience the same situation have different stress responses depending on their mindset. There is a physiological stress reaction in those who perceive the situation as stressful, but not in those who do not perceive it as stressful. Adversity has less impact on people who view stress.

The “tend-and-befriend” response, as it is often referred to, is yet another positive stress response that occurs when we talk to a close friend or family member and express our woes. Social connection results in the production of oxytocin which makes us feel more connected, trusting, open and loving.

There are a number of ways to stimulate oxytocin production, including cuddling, kissing, hugging, stroking a pet, sexual intimacy. This is a hormone that enhances someone’s mood and boosts emotions.

And it doesn’t end there either. The tend-and-befriend response fires up the social caregiving system by releasing oxytocin while inhibiting the fear centres of the brain. As a result, we feel more empathy, connection, and trust toward one another. Disasters like earthquakes and tsunamis demonstrate this. When we are under acute stress, we become more open, cooperative, and giving.