Cortisol suppresses inflammation caused by stressors.

Cortisol, often referred to as the “stress hormone,” is produced by the adrenal glands and plays a crucial role in regulating various bodily functions, including the body’s response to stress and inflammation.  It helps keep inflammation in check by suppressing the immune system’s inflammatory response. When cortisol levels are adequate, it prevents excessive inflammation, which is essential for maintaining brain health. Low cortisol levels can lead to increased inflammation in the brain because cortisol’s anti-inflammatory effects are diminished, allowing the immune system to overreact to stressors. When a new stressor is introduced, the already heightened inflammatory response can become even more pronounced, leading to further brain inflammation. 

Inflammation in the brain can have several detrimental effects, including cognitive decline, mood disorders, brain fog, lack of focus and energy, and increased risk of neurodegenerative diseases. Chronic inflammation can damage brain cells and disrupt normal brain function, leading to symptoms such as memory loss, confusion, and depression. 

There is a growing body of research linking low cortisol levels to conditions such as long COVID and chronic fatigue syndrome (CFS). Studies have shown that COVID-19 proteins can remain in the brain long after the initial infection, causing a drop in cortisol levels and leading to persistent inflammation and exaggerated stress responses. A 2024 animal study out of the University of Colorado at Boulder is the latest to document the link between dropping cortisol levels and brain inflammation, specifically in the instance of long COVID or CFS. Stress causes inflammation in the brain unless cortisol suppresses that damage. Normal cortisol levels control this process, but when cortisol levels lower because of outside factors, new stressors repeatedly trigger inflammation in the brain, as explained in this discussion of the study. This process can explain the neurological symptoms seen in long COVID patients, such as brain fog, fatigue, and depression.

Similarly, CFS has been associated with low cortisol levels. A paper in the Lancet analyzed patients with CFS and how they responded to corticosteroids. Patients with CFS often exhibit mild hypocortisolism, which can contribute to chronic fatigue and other symptoms, and the weakened stress response in these patients can exacerbate their condition, making it difficult to cope with daily stressors- for the same reasons that those patients with long COVID might.

Other factors can lower cortisol levels, including chronic stress, poor sleep, an unhealthy diet, a lack of physical activity, and certain medical conditions. If this state of low cortisol extends for a longer period of time, then the brain inflammation that may be triggered through new stressors could become chronic and damage the brain permanently. 

Surveying a patient’s cortisol level, particularly if they have symptoms of long COVID, chronic fatigue, or brain fog, would be wise. Cortisol testing, particularly the Advanced Adrenal Stress Test from Precision Point Diagnostics, can assess the overall level of cortisol in a patient and track cortisol levels over a 24-hour period. This comprehensive testing method measures cortisol, DHEA, and secretory IgA in saliva samples, providing a more accurate picture of adrenal function and stress response.

By monitoring cortisol levels throughout the day, healthcare providers can identify patterns of adrenal dysfunction and develop personalized treatment plans to address fatigue, insomnia, thyroid disorders, and other related conditions.

If a patient is found to have low cortisol, or if their cortisol cycle is out of sync, then training those patients to avoid and handle stressors is crucial for maintaining healthy cortisol levels and preventing inflammation-related conditions. Stress management techniques, such as mindfulness, relaxation exercises, and cognitive-behavioral therapy, can help patients develop effective coping strategies and reduce their overall stress levels. By learning to manage stress more effectively, patients can improve their adrenal function and reduce the risk of inflammation and related health issues. Lifestyle changes, such as regular exercise and adequate sleep can also help. Supplements or perhaps even corticosteroids may be possible treatments in some cases as well. As always, the first step should be functional testing for any condition to chart a game plan.