A new study involving Liverpool researchers has shown that many of the symptoms in fibromyalgia syndrome are caused by antibodies that increase the activity of pain-sensing nerves throughout the body.

Between January 1st, 2020 and December 31st, 2021, 3,814,479 participants were included in the study (888,463 cases and 2,926,016 controls). After matching, the COVID-19 cohort exhibited significantly higher risks of rheumatoid arthritis (aHR:2.98, 95% CI:2.78–3.20), ankylosing spondylitis (aHR:3.21, 95% CI:2.50–4.13), systemic lupus erythematosus (aHR:2.99, 95% CI:2.68–3.34), dermatopolymyositis (aHR:1.96, 95% CI:1.47–2.61), systemic sclerosis (aHR:2.58, 95% CI:2.02–3.28), Sjögren's syndrome (aHR:2.62, 95% CI:2.29–3.00), mixed connective tissue disease (aHR:3.14, 95% CI:2.26–4.36), Behçet's disease (aHR:2.32, 95% CI:1.38–3.89), polymyalgia rheumatica (aHR:2.90, 95% CI:2.36–3.57), vasculitis (aHR:1.96, 95% CI:1.74–2.20), psoriasis (aHR:2.91, 95% CI:2.67–3.17), inflammatory bowel disease (aHR:1.78, 95%CI:1.72–1.84), celiac disease (aHR:2.68, 95% CI:2.51–2.85), type 1 diabetes mellitus (aHR:2.68, 95%CI:2.51–2.85) and mortality (aHR:1.20, 95% CI:1.16–1.24).

Plausible, need to reread.

More about the Icelandic study of PTSD and autoimmunity and the role stress plays in autoimmunity.

This was about correlation, not causation, but a study of more than 100,000 people concluded that the presence of a stress-related disorder (PTSD, acute stress disorder, etc) makes someone 30-40% more likely to also be diagnosed with an autoimmune disease (such as celiac disease, psoriasis, or rheumatoid arthritis).

I'd argue this number is an underestimation, considering some of us suffered with undiagnosed celiac disease for 30 years after our traumas, and the study was 30 years long.

Chronic and severe acute stress has been a known autoimmune trigger for a long time, but this is an unprecedented study in its size, length, and comprehensiveness.