By Dr. John Thomas
Whether you are in the dry South, the humid East, or the cool plains of the West, signs of spring can be a bittersweet welcome if you, along with the other 40-60 million Americans, suffer from allergies.¹
Seasonal allergies are caused by a sensitive immune system response to airborne mold spores or pollens from grass, trees, and weeds. Symptoms can range from a mild runny nose and foggy head to itchy eyes, sneezing and coughing, and this response can cause unwanted stress and anxiety.
With so many chronic illnesses stemming from improperly functioning stress responses and immune functions, researchers have been digging deeper into the relationship between our mental health and how our body deals with allergens.
When our body is exposed to pollen, the allergen binds to IgE receptors on mast cells in our immune system. Mast cells protect our bodies from various types of pathogens outside of allergens, such as bacteria and parasites. They are primarily located in vascularized connective tissues or the submucosal layers of the gut and respiratory system.
Our body’s overall response to an allergen depends on which mast cells are activated and how. With seasonal allergies, allergens are inhaled via nasal or bronchial passageways, stimulating mucosal mast cells.² This can lead to increased mucus production by local epithelial cells, increased nasal irritation due to the release of various intracellular mediators, and airway congestion due to constricting blood vessels.
One of the main pro-inflammatory mediators released by mast cells is histamine, whose role is to help increase the permeability of blood vessels to allow other immune cells to infiltrate the area of attack. A popular target in many over-the-counter allergy medications, histamine release is deeply interconnected with our immune response.
When under stress, our immune system, mediated by the release of cortisol and other hormones, is down-regulated, leaving our body more susceptible to experiencing the uncomfortable symptoms of seasonal allergies.
Research on the connection between mental health and allergies is still in its early stages. A review published in the International Journal of Environmental Research and Public Health found that a history of seasonal allergies was associated with significantly higher odds for lifetime mood swings, including anxiety issues.³
Another review in Innovations in Clinical Neuroscience looked at the likelihood of a relationship between mood disorders and allergies in 12 different studies.4 After controlling the variables and variations in methodologies used, the researchers found that 99.9% of individuals studied showed a positive relationship between allergy symptoms and anxiety. Possible allergy-mediated variables that impacted the participants’ mood states included:
What is most intriguing is that these reviews, along with a study looking at the effects of allergic rhinitis on adolescents, found that it was the allergy-related symptoms that caused higher rates of anxiety and depression in adolescents.5
These symptoms can negatively impact important aspects of our daily routine, such as sleep, which is critical for our mental health and emotional well-being. Furthermore, other unpleasant seasonal allergy symptoms, such as brain fog or fatigue, can cause increased levels of frustration and stress. Our reaction to the unpleasant symptoms alone could be a catalyst for the stress we feel during allergy season.
This anticipation of unwanted symptoms increases our overall stress and can produce enough cortisol over time to down-regulate the function of our immune system. With a weakened immune response, the body is less likely than before to be able to handle small doses of a pathogen. Thus, it is quite possible that in a prolonged anxious state, we may have a harder time fending off seasonal allergy irritants.
Genetics and Our Allergen ResponseIf our allergic response can be characterized by the triggering of mast cells and the release of histamine and other cellular mediators, then this response can be characterized by the degradation of histamine. Histamine can be degraded via methylation by histamine-N-methyltransferase (HNMT) or with the enzyme diamine oxidase (DAO).
DAO is synthesized from the gene AOC1, and without it, the body would experience a histamine overload and eventually, histamine intolerance. If a parent has this genetic mutation, and it is passed down to the child, they will likely react to allergens more severely than those with normal levels of DAO.
With a large percentage of DOA produced in the gut, genetics is not the only way that its synthesis can be negatively impacted. Gut health and bacterial flora, as well as nutrient consumption, can have an impact on both mental and emotional stability.
Certain fermented foods—such as yogurt, undigested animal protein, and collagen—have been found to increase levels of histamine in the body.6 Overproduction of histamine can lead to a potentially longer and more severe allergic response. Maintaining a nutritious, wholesome diet can help prevent aggravation of the allergic response and any subsequent stress that may come from dealing with it.
We know that the relationship between anxiety and seasonal allergies is complex and interconnected, but we still don’t have a whole lot of empirical data on how they affect one another. However, recent studies and reviews have shown that those who experience seasonal allergies are also more likely to experience negative mood states, such as anxiety.7
Since stress lowers the strength of the immune system through hormonal and chemical mediators, it is possible that anxiety-induced stress can lead to a weakened immune response and a bout of allergic discomfort.
The production of DOA in the gut is directly responsible for the degradation and length of the allergic response. Whether through genetic mutation or improper nutrient intake and gut imbalance, if DOA is imbalanced, so are histamine levels and the overall allergic response.
The relationship between seasonal allergies and anxiety depends on numerous variables in our lives and our bodies. But by understanding how our stress response can influence our immune system’s ability to fight off irritants, we can approach our wellness from a more holistic approach, so we can live—and breathe—easier.
1" Hay Fever (Rhinitis) | Symptoms & Treatment | ACAAI Public Website." https://acaai.org/allergies/types/hay-fever-rhinitis. Accessed 10 Jul. 2019.
2 “Immunobiology: The Immune System in Health and Disease -NCBI.” 2001. https://www.ncbi.nlm.nih.gov/books/NBK10757. Accessed 22 Jun. 2019.
3 “Seasonal Allergies and Psychiatric Disorders in the United… -NCBI.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164754/. Accessed 22 Jun. 2019.
4 “Allergic Rhinitis: Relationships with Anxiety and Mood…- NCBI.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159540/. Accessed 22 Jun. 2019.
5 “The Burden of Allergic Rhinitis and Allergic Rhinoconjunctivitis … -Science Direct.” April 2018. https://www.sciencedirect.com/science/article/pii/S1081120618302503. Accessed 22 Jun. 2019.
6 “Probiotics and Disease: A Comprehensive Summary-Part 2… -NCBI.” December 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312833/. Accessed 22 Jun. 2019.
7 "Seasonal Allergies and Psychiatric Disorders in the United States - NCBI." 8 Sep. 2018, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164754/. Accessed 8 Jul. 2019..