The Effects of Stress on the Brain

In the short term, stress can positively boost energy and focus, such as during an athletic competition or a public speaking engagement. But over the long term, the insidious effects of chronic stress on the brain are devastating, impacting everything from its size/function to its epigenetics (the way its genes express themselves). The basic stress reaction begins in the hypothalamic-pituitary-adrenal axis (HPA-Axis), when a stressful stimulus (rush project from the boss, argument with a significant other, etc.) causes it to signal the production of more cortisol to aid in the fight or flight response. Cortisol does so by suppressing the immune system and spiking the availability of glucose, which both the brain and the body’s muscles must draw on to successfully survive attacks.

In an acute situation, this can be life-saving, but chronically in response to a stressful job, destructive relationship, etc., it wreaks havoc on the brain (and promotes body fat storage). Structurally, it tends to shrink the hippocampus (which is responsible for mitigating the stress reaction, among many other things), and most troublingly, the prefrontal cortex (which is responsible for focus, concentration, and judgment). In other words, the neural shrinkage caused by chronic stress reduces one’s intelligence. And it doesn’t stop there. It also affects one’s epigenetics–specifically, the way the brain’s genes express themselves (think of your brain’s genes as its hardware, and its epigenetics as its software–the way those genes present themselves). Indeed, a recent clinical experiment with rats examined the effects on the HPA-Axis associated with nurturing in infancy.  

The study revealed that the baby rats whose mothers nurtured them developed more cortisol receptors, which better enabled them to handle stress and avoid its negative structural manifestations over the long term. Meanwhile, baby rats with neglectful mothers were at the mercy of stress reactions, suffering cognitively devastating structural changes to their brains over their lives. And here’s the kicker: these were epigenetic changes, so they became heritable, i.e., capable of being passed to subsequent generations.

Indeed, chronic stress is cognitively terrifying, but there are ways to prevent and/or reverse its effects: exercise and meditation, to name a couple.  Clinical studies have repeatedly shown that by practicing activities that increase one’s mindfulness, the stress-affected structures in the brain can regenerate and the negative neurological effects of chronic stress  can be mitigated (if not prevented entirely). Take a look at some of Mojo’s earlier blog posts to learn more about meditation, and click here to watch the TED video on the effects of stress on the brain. Both serve as valuable resources for stress management in this new year!

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