An autoimmune disease develops when your body fails to distinguish between itself and foreign invaders it needs to attack. Approximately 1 in every 20 people worldwide has an autoimmune disease. Some diseases develop most commonly during childhood, others in early adulthood, and some develop later in life. Experts have identified more than 80 unique autoimmune diseases, many of which are lifelong conditions. (Source, Source)
There are two types of triggers to consider in autoimmune diseases — those that bring about disease development, and those that trigger flares. In this article, we’ll look at both.
What Causes Autoimmune Diseases?
Scientists don’t know what causes autoimmune diseases, but some people are more likely to develop them. For example, there’s a genetic component, which means a person with certain inherited traits or genes from their family may be more likely to develop an autoimmune disease. (Source)
Beyond that, some autoimmune diseases are more prevalent among specific groups. Overall, autoimmune diseases are most common in women. There are also significant variations between different ethnicities. African Americans, for example, are more likely than European Americans to develop systemic lupus erythematosus (SLE) but less likely to develop type I diabetes or multiple sclerosis (MS). (Source)
So, why do some people with dispositions develop autoimmune diseases while others don’t? There’s evidence that viruses, bacteria, hormonal changes, stress, drugs, toxins, and some lifestyle factors can trigger autoimmune diseases in people who are at risk. (Source, Source)
Viruses
It’s widely accepted that viral infections are a major factor in the development of autoimmune diseases. However, the connections between the two are poorly understood.
One theory is that antigens (substances that trigger an immune response) within the viruses may be similar in shape and size to molecules within the body. It’s possible this phenomenon, termed “molecular mimicry,” may confuse the body, so it begins attacking itself.
Alternately, some experts have proposed something called “bystander activation,” where the immune system overreacts to a viral infection, triggering inflammation in a specific area of the body and initiating the release of the body’s own antigens, which the immune system attacks. (Source)
Bacteria
Regardless of your autoimmune status, your body is full of bacteria. Some bacteria are good and help you stay healthy, but others are harmful and can make you sick. Your gut microbiome consists of trillions of microorganisms in your gut, including bacteria.
Immune dysfunction can be triggered by changes in the gut microbiome. The inflammatory bowel diseases Crohn’s and ulcerative colitis, for example, are characterized by abnormal growth of a specific type of gut bacteria called proteobacteria. (Source)
A well-functioning body depends on balance, and it’s not just too many bacteria that can cause problems. Antibiotic use can disrupt the balance within the gut microbiome, potentially triggering autoimmune diseases. (Source)
Hormonal Changes
Events characterized by major hormonal changes, such as pregnancy, can lead to the development of autoimmune diseases. The influence of hormones on autoimmunity partly explains why women are more affected than men.
Women undergo drastic hormonal changes at puberty and again at menopause. As noted, in women with children, there’s another boost in activity during pregnancy. Estrogen, progesterone, androgens, leptin, oxytocin, and prolactin (all hormones that can increase or decrease in concentration) play roles in the body’s immune response. (Source)
Pregnancy doesn’t just trigger the development of autoimmune disease in the moment, either. There’s evidence that having a pregnancy can increase a woman’s risk of developing an autoimmune disease decades later. (Source)
Environmental Factors
Environmental factors play a role in immunity. Cigarette smoke, pesticides, mercury, silica, and other substances we commonly come into contact with have been linked to the development of autoimmune diseases. (Source, Source)
Stress
Stress is strongly associated with a range of negative health outcomes. Some conditions are stress-induced, meaning stress causes them. Others are stress-aggravated, which means stress can make them worse. In the case of autoimmune diseases, it seems stress (both physical and emotional) may trigger or worsen certain conditions. (Source, Source)
Poor Sleep
Sleep has a restorative effect on immune processes. There’s evidence that long-term lack of sleep (or poor quality sleep) could lead to the development of autoimmune diseases. Interestingly, there’s also evidence that the sleep disorder narcolepsy may be rooted in autoimmunity, indicating there are many connections between autoimmunity and sleep that we don’t yet understand. (Source)