Does Stress Affect Brain Health?

Short-term stress is natural and necessary for human health. By definition, stress is any situation that requires us to change. Our ancestors depended on the stress response to help them out-run predators and survive other threats to life, and in modern-day life, we still need a bit of stress to help us adapt to ever-changing environments. Yet, when stress lingers, it can impact our health and happiness.

Stress that won’t go away is detrimental to digestion, immunity, and more. It also has a profound effect on brain health. It contributes to memory and learning problems, forgetfulness, brain fog, trouble sleeping, and more. It has short and long-term effects, so it’s important to understand the stress response and manage it through nutritional supplements and lifestyle changes.

What is the HPA Axis?

The hypothalamic-pituitary-adrenal (HPA) axis is a communication loop that influences the body’s stress response. It’s called an axis because it refers to the relationship between the hypothalamus and pituitary gland, located in the brain, and the adrenal gland, located at the top of the kidneys.

During times of stress, the hypothalamus, pituitary gland, and adrenal glands communicate with one another. The hypothalamus sends a chemical signal to the pituitary gland, which releases adrenocorticotropic hormone (ACTH). This hormone activates the adrenal glands, triggering them to release cortisol and adrenaline, two of the body’s primary stress hormones.

When cortisol levels rise to a sufficient level to manage stressors, the body ideally suppresses the hypothalamus and pituitary gland, so the adrenal glands stop releasing stress hormones, turning off the fight or flight response when it is no longer needed. However, bouts of chronic stress disrupt this feedback loop. The hypothalamus and pituitary gland do not stop the adrenals from releasing cortisol and adrenaline. This leads to adrenal insufficiency and imbalance.

Now, let’s consider why a basic understanding of the HPA axis is essential to brain health.

Stress Hormones and the Hormonal Cascade

All hormones in the body contribute to a hormonal cascade, meaning that each hormone interacts with all other hormones either directly or indirectly. Put simply, no hormone in the body acts alone.

For example, cortisol and pancreatic hormones, such as insulin and glucagon, significantly impact blood sugar levels. When you haven’t eaten in a while, blood sugar levels drop. The pancreas then releases glucagon to prevent blood sugar from dropping too low. When blood sugar and insulin are sufficient, the pancreas suppresses glucagon. But when cortisol levels are unbalanced during the stress response (either too high or too low), the body struggles to efficiently regulate blood sugar, a process critical to producing energy, control appetite, and regulate mood.

Stress also affects sex hormones in both men and women. In women, estrogen and progesterone levels are affected during adrenal imbalance. Pregnenolone, for instance, is a steroid that plays a role in creating progesterone. Without steady cortisol supplies, the body steals pregnenolone to convert it into cortisol, and this phenomenon is called pregnenolone steal. In men, stress can contribute to low testosterone, which is linked to low mood, lethargy, and apathy.[1]

When it comes to weight management, elevated cortisol levels trigger the body to consistently produce glucose, leading to increased blood sugar levels, appetite, and even insulin resistance.[2]

Stress and Sleep

If you’ve ever experienced a string of restless nights, you know the brain needs sleep to function optimally. Elevated cortisol levels can dramatically decrease sleep quality and duration, leading to a lack of focus, slowed reaction time, lowered capacity for problem-solving, forgetfulness, moodiness, increased irritability, and low mood.[3]

The Stress, Gut, Brain Connection

Stress also impacts the digestive system and gut health. Gut function has a profound effect on the brain. This bidirectional relationship is called the gut-brain axis, or GBA, and refers to the central nervous system throughout the entire body and the enteric nervous system within the gut. The gut contains millions of neurons that connect to the brain via the vagus nerve. This nerve facilitates communication between the gut and brain, and studies show that when stress disrupts normal vagus nerve activity , digestive problems can occur.[4]

Furthermore, elevated cortisol levels increase intestinal permeability (leaky gut), allowings particles such as proteins, bacteria, undigested foods, and toxins to move into the bloodstream, leading to inflammation and impaired blood-brain barrier integrity.[5]

The gut microbiome also influences brain health, as many gut microbes produce short-chain fatty acids, such as butyrate, which has been extensively studied for its role in vagus nerve activity and immune system regulation.[6]

RELATED CONTENT: Mind Diet: How DMG Supports Brain Health

Adaptogens for Stress Support*

Adaptogens are a group of botanicals that naturally support your body’s ability to deal with stress.* Common adaptogens include ashwagandha, ginseng, Rhodiola Rosea, holy basil, licorice root, and astragalus. Like any nutritional or herbal supplement, it’s important to discuss options and dose with your functional medicine doctor.

There are multiple players involved in managing stress and optimizing brain health. By understanding these mechanisms, you can more effectively intervene in the stress response, learn strategies to mitigate it, and ultimately take more control of your life.

By Dr. Ramneek Bhogal

[1] Kheirkhah, F., Hosseini, S. R., Hosseini, S. F., Ghasemi, N., Bijani, A., & G Cumming, R. (2014). Relationship between testosterone levels and depressive symptoms in older men in Amirkola, Iran. Caspian journal of internal medicine, 5(2), 65–70.

[2] Geer, E. B., Islam, J., & Buettner, C. (2014). Mechanisms of glucocorticoid-induced insulin resistance: focus on adipose tissue function and lipid metabolism. Endocrinology and metabolism clinics of North America, 43(1), 75–102. https://doi.org/10.1016/j.ecl.2013.10.005

[3] Kalmbach, DA, Anderson, JR, Drake, CL. The impact of stress on sleep: Pathogenic sleep reactivity as a vulnerability to insomnia and circadian disorders. J Sleep Res. 2018; 27:e12710. https://doi.org/10.1111/jsr.12710

[4] Sahar T, Shalev AY, Porges SW. Vagal modulation of responses to mental challenge in posttraumatic stress disorder. Biol Psychiatry. 2001 Apr 1;49(7):637-43. doi: 10.1016/s0006-3223(00)01045-3. PMID: 11297721.

[5] Obrenovich M. (2018). Leaky Gut, Leaky Brain?. Microorganisms, 6(4), 107. https://doi.org/10.3390/microorganisms6040107

[6] https://www.sciencedirect.com/science/article/abs/pii/S0197018616301747