Key points
- Stress-driven inflammation affects both physical and mental health
- Stress is associated with poorer cardiovascular health
- Stress results in neuroinflammation that has a raft of health effects and may contribute to depression, anxiety, and other mental health disorders
In this issue of the Carb-Appropriate Review, we have looked at the effect of stress on immunity. Part of the immune-inflammatory cascade is the often talked about, but perhaps seldom properly understood concept of inflammation.
What is inflammation?
Inflammation is part of the body’s normal response to damage from injury, irritants, and infection. It is a protective response of innate (not adaptive or pathogen-specific) immunity, involving immune cells, blood vessels, and inflammatory mediators. The main functions of inflammation are:
- Eliminate the cause of cell injury
- Clear damaged tissue and metabolic waste
- Trigger tissue repair
Inflammation is marked by the cardinal signs of calor, dolor, rubor, tumor, and functio laesa, or heat, pain, redness, swelling, and loss of function.
Inflammatory balance is important, as too little inflammation or an inability to properly initiate and maintain inflammatory responses promotes excessive tissue damage and an inability to repair. Conversely, chronic, excessive inflammation also results in damage and is associated with a range of diseases including allergy states, autoimmune conditions, cardiovascular disease, neurodegenerative disorders, and metabolic disorders like diabetes.
Stress and inflammation
In response to physical stress, inflammatory processes occur. These can also occur in response to psychological stress.1 Several stress-related illnesses are associated with increased inflammatory activity. For example, post-traumatic stress disorder (PTSD)2-4 and chronic anxiety disorders are associated with increased levels of pro-inflammatory cytokines (especially interleukin‐1β and tumour necrosis factor‐α).3 In PTSD, the resulting inflammation is thought to cause structural alterations to the brain, especially the amygdala, hippocampus, and frontal cortex, potentially resulting in further worsening of stress and emotional problems.2
Stress-driven inflammation also has an association with cardiovascular disease. Stress increases inflammatory markers such as c-reactive protein, and this measure of systemic inflammation has a better predictive value for risk of cardiovascular disease than either total or LDL cholesterol.5
From: https://www.frontiersin.org/articles/10.3389/fimmu.2018.02031/full?&utm_source=E
Stress is thought to play an important role in neuroinflammation or inflammation in the brain. Stress is marked by the release of various neurochemicals that activate the inflammatory cascade (via mast cells and other inflammatory cells). Further systemic stress results from this with the release of cortisol (driven by corticosteroid releasing factor) and there is an activation of the sympathetic nervous system (‘fight or flight’ system), the hypothalamic-pituitary axis (HPA), and secondary release of stress hormones including norepinephrine (adrenaline) and glucagon. These and other cytokines associated with stress initiate the other responses resulting in further stress-inflammation and might result in disturbances to gut-integrity and chronic inflammation.1
References
1. Black PH. Stress and the inflammatory response: A review of neurogenic inflammation. Brain, Behavior, and Immunity. 2002;16(6):622-53.
2. Kim TD, Lee S, Yoon S. Inflammation in Post-Traumatic Stress Disorder (PTSD): A Review of Potential Correlates of PTSD with a Neurological Perspective. Antioxidants. 2020;9(2):107.
3. Renna ME, O’Toole MS, Spaeth PE, Lekander M, Mennin DS. The association between anxiety, traumatic stress, and obsessive–compulsive disorders and chronic inflammation: A systematic review and meta-analysis. Depression and Anxiety. 2018;35(11):1081-94.
4. Speer K, Upton D, Semple S, McKune A. Systemic low-grade inflammation in post-traumatic stress disorder: a systematic review. J Inflamm Res. 2018;11:111-21.
5. Fioranelli M, Bottaccioli AG, Bottaccioli F, Bianchi M, Rovesti M, Roccia MG. Stress and Inflammation in Coronary Artery Disease: A Review Psychoneuroendocrineimmunology-Based. Frontiers in Immunology. 2018;9(2031).
