The Neurobiology of Stress: Part 1

“The stress is killing me!”

We’ve all said it — though we were probably exaggerating — but stress can have negative consequences on cognitive health. Luckily, a basic understanding of what stress is and how to deal with it can help us lessen the effects.

Stress can be a lifesaver. For our ancient ancestors, it’s what sent them running when a saber-toothed tiger approached. But now, short of dodging the occasional bad driver, most people don’t face dangerous external or predatory threats. Our stress stems from a daily onslaught of multiple demands. Modern pressures materialize in different forms: managing deadlines at work, tending to family’s needs or worrying about paying bills.

These stresses, unlike a dash from a predator, tend to be ongoing. If not relieved, chronic pressure and tension can put us at risk for health problems. Negative manifestations of stress might include disturbed sleep, heart disease, depression, or problems with digestion and obesity. Chronic heightened anxiety also affects on the brain, altering the physical structure and impacting the way we think and remember.

What You Need to Know

First, the biology. When you are physically threatened — say, by a swarm of bees or a car that runs a red light — your body immediately becomes aware of these threats through nerve signals. Then, your hypothalamus (an almond-shaped region at the base of your brain but above the brain stem) sends a signal down the spinal column to the adrenal glands (located at the top of your kidneys), encouraging them to release a combination of hormones, two of which are adrenaline and cortisol.

Adrenaline increases your heart rate and blood pressure. It pushes more oxygen-rich blood to the brain and muscles, giving you the quick energy you need for a flight or fight response. Adrenaline is what makes you feel “pumped” before a race or a public speech.

Cortisol increases glucose (sugar) in the bloodstream, improving its use for energy by the brain. When stress becomes overwhelming, cortisol helps us deal with impounding stress by shutting down those bodily functions not essential for immediate survival, such as the reproduction and immune systems.

Together, adrenaline and cortisol work together to make the stored energy in our bodies (fats and sugars) available to us when we need them quickly. Adrenaline takes only seconds to work, while cortisol is effective from minutes to hours.

The Benefits of Stress

Reacting to stress in the short term is actually good for us. Adrenaline and cortisol give that quick energy boost and summon more brain power to work through the challenge of immediate stress, which increases the connections between neurons in the brain. These hormones also give a sense of heightened awareness and memory, and reduce sensitivity to pain. After a perceived threat passes, the body self-regulates, decreasing hormone levels in order to return to homeostasis, a normal state of balance.

But that’s when everything goes according to plan. In the modern world, stress can become continuous, and that can mean bad things for the brain. So, what is the takeaway? That stress is an inevitable part of life and how you react to stress or change the way it negatively impacts your life will help improve your motivation, mood and cognitive functioning.

To learn more about what chronic stress can do the brain, read The Neurobiology of Stress: Part 2.