Under Pressure

Whenever you experience stress, whether it’s from a work deadline, relationship woes, financial anxiety, or a bear on the trail, your body’s adrenal glands release cortisol, a key stress-related hormone.

This stress response evolved over time as a survival mechanism, boosting alertness and energy when facing immediate danger. However, when cortisol is chronically elevated, there can be negative impacts on the brain.

How cortisol levels affect brain health

Studies show a correlation between the size of the hippocampus, the seahorse-shaped structure in the brain that’s involved in memory, and stress response regulation and elevation. There are also negative impacts on the prefrontal cortex, the area of the brain responsible for executive functioning, causing erosion to our capacity for focused attention, impulse control, and flexible thinking.

In order to examine the relationship between stress and memory, researchers have conducted studies both in laboratories and in the real world. A longitudinal study that repeatedly measured the basal cortisol levels of a group of healthy older adults for five years found that participants who had persistently high cortisol had markedly smaller hippocampi on MRI. They also performed worse on memory tasks than the study participants whose cortisol stayed within the normal range.

Researchers found that the extent of hippocampal shrinkage was very closely related to the degree of cortisol elevation, suggesting that chronic stress hormones can actually erode the brain tissue that we rely on for learning and recall, which can, in turn, have significant impacts on memory.

A 2019 review published in Frontiers in Aging Neuroscience brought dozens of human and animal studies together. From the compiled data, a clear message emerged: chronically high levels of cortisol may pave the way for dementia.

Across clinical trials, people with persistently elevated cortisol scored lower on memory, language, decision-making, and processing-speed tests. In healthy adults, study participants who had higher cortisol levels were at greater risk of experiencing cognitive decline or Alzheimer’s disease years down the line.

Further, patients who were already experiencing mild cognitive impairment or Alzheimer’s consistently showed higher cortisol in their cerebrospinal fluid, and those with the sharpest cortisol spikes deteriorated the fastest.

The emerging body of evidence suggests that cortisol may be more than just a stress marker; it could also be an active driver of the neurodegenerative process and a potentially promising target for lifestyle or drug interventions aimed at protecting long-term brain health.

Stress hygiene: A preventive medicine revolution?

Just as dental hygiene became standard practice for proactively protecting your teeth, and sleep hygiene as a strategy for a better night’s rest, “stress hygiene” is gaining traction as a preventive measure for cognitive health. Stress hygiene refers to actively managing stress through daily practices aimed at reducing cortisol levels and mitigating its harmful effects.

Lifestyle changes to lower cortisol

Teshamae Monteith, MD, professor of clinical neurology and chief of the headache division at the University of Miami Miller School of Medicine, notes that many of us may have been revved up for so long that being at an elevated stress level actually feels normal.

Identifying that hidden tension is the first step in stress hygiene. Here are a few daily habits that can help keep cortisol in check and protect brain health:

Check-ins

Schedule brief pauses during the day to scan yourself from head to toe. Notice how you are feeling: do you have tight shoulders, a clenched jaw, shallow breaths, or other stress-related signs?

Stable daily routine

Incorporating consistency in your day-to-day, through practices like regular mealtimes, planned gym sessions, and realistic work blocks, may help avoid stress.

Micro de-stress breaks

When stress starts to build, insert a quick-release valve; try activities like deep breathing, meditation, exercise, or hobbies that you enjoy.

At-home cortisol testing: Stress in clearer focus?

Advancements in medical testing now allow for convenient, at-home saliva-based cortisol tests. These tests can measure cortisol variations throughout the day, providing insight into individual stress patterns.

It’s important to interpret cortisol test results carefully and to take these results within the context of the broader picture. Because cortisol naturally fluctuates throughout the day due to various factors, including sleep patterns, physical activity, and dietary habits, it’s important to be cautious in the interpretation of these results.

Health professionals caution that cortisol results must be integrated with a comprehensive assessment of lifestyle and clinical history to provide meaningful insights into an individual’s stress and overall health. In short, cortisol test results may provide a useful piece of data, but it certainly shouldn’t be the only one you’re relying on.

Personalized stress management: The future of brain health?

Emerging healthcare trends point toward personalized stress management as being important for preserving cognitive health. By integrating data from cortisol tests, wearable technology, and personalized healthcare approaches, future strategies could provide targeted interventions specifically tailored to an individual’s stress profile.

By integrating stress hygiene as a foundational component of preventive medicine, you may be able to positively impact your cognitive health and overall quality of life.

This article was originally published in the October 2025 issue of alive magazine.