- Previous research studies in rodent models indicated a link between anxiety, depression and asthma.
- A new study of Taiwan reported a strong association of allergic diseases to psychiatric and emotional health in humans.
- Researchers theorized that asthma and psychiatric disorders share underlying causes, including chronic stress, genetic factors, and inflammation.
Asthma is a complex, multifaceted disease that affects health in several ways. But not many are aware that the disease can be much more than just sneezing, coughing and congestion.
Studies show that there is an elevated prevalence of anxiety and major depressive disorder (MDD) among asthma patients compared to the general population. Also, patients with MDD, bipolar affective disorder, or other common mood disorders, stand at a higher risk of developing IgE-mediated allergic conditions including asthma, allergic rhinitis (hay fever) and atopic dermatitis (eczema). These are known as the three A’s.
Linking the 3 A’s with psychiatric disorders
Despite several studies, there existed no substantial research linking the 3 A’s and the overall risk of developing psychiatric disorders, until now. To study this in a large sample of people, the researchers used an extensive database of health insurance claims in Taiwan, covering a 15 year period. Unlike previous studies, this one included patients of all ages.
The study was the brainchild of Dr. Nian-Sheng Tzeng, a psychiatrist at Tri-Service General Hospital in Taipei. Tzeng was instigated to begin the research after noticing a pattern of emotional suffering in some patients with the three A’s, and hence, wanted to clarify whether these allergic diseases are associated with psychiatric disorders.
The study, published in the journal Frontiers in Psychiatry, revealed that patients with asthma and hay fever have an increased risk of developing psychiatric disorders. Almost 11% of patients with common allergic diseases developed a psychiatric disorder within a 15-year period, compared to only 6.7% of those without any of the three A’s, indicating almost double the risk.
So, why might patients with certain allergic diseases have a higher risk of psychiatric disorders?
- Inflammation may be the factor that connects allergic diseases and psychiatric disorders.
Inflammation is central to allergic diseases and is also found to be linked to depression and anxiety. It is, therefore, possible that it may contribute to psychiatric disorders in the same patients. The psychological stress of a psychiatric disorder might also contribute to physical symptoms.
- Hypoxia or lack of oxygen has a direct impact on the brain.
Besides, during an asthma attack, muscles that are around the airways tighten, leading to swelling of the the airways' linings. The swelling allows less oxygen to be taken in by the body and used by vital organs. Lack of oxygen affects the brain the most: the brain uses 20% of the body's oxygen. 4-6 minutes of no oxygen and the brain cells begin to die. The hippocampus, the part of the brain located in the medial temporal lobe and responsible for converting short-term memories to long-term memories, is very susceptible to hypoxia. Memory loss can only occur in a severe asthma attack where breathing becomes completely restricted. The amount of oxygen being taken in is less than 50% of normal capacity.
When treated quickly, the effects of less oxygen intake are almost nothing, however, a long period of time without enough oxygen can affect the normal function of the brain.
Inflammation, on face, is a good thing. The National Center for Biotechnology Information defines it simply as “the body’s immune system’s response to stimulus.” It allows the body to ramp up its defenses in order to heal wounds or fighting off bacteria. The problem is that, in too many cases, the body perceives an enemy when there isn’t one, and switches on an inflammatory response that never gets turned off.
Actionable information
The current study did not examine the potential cause of this phenomenon and researchers need to complete further studies to identify the precise mechanisms involved. However, knowing that there is a link between allergic diseases and psychiatric disorders could help doctors to care for their patients.
Paula Carino, LMHC, a psychotherapist based in New York City, points out that the body and the nervous system express stress in a variety of ways. “Someone may process trauma somatically via allergies, but if the initial trauma isn't resolved, they could start expressing it in more dramatic ways like psychiatric disorders,” she says.
Research has shown that stress can trigger or worsen existing allergic diseases. As a result, stress can become a vicious cycle that exacerbates an individual’s allergy or asthma symptoms, while affecting their mental or emotional health.
Even without knowing the root cause as to why allergies might be linked with psychiatric disorders, the medical community can still take action to be aware and proactive; thereby, helping to limit psychiatric stress in allergy patients.
