Question

I know that ME and CFS are both classified by the World Health Organisation as a neurological disease. But I’ve also seen statements on the internet to say that ME is now being classified as an autoimmune disease. Is this correct?

Answer

Autoimmune diseases are conditions where the immune system starts to produce harmful antibodies that can attack the body’s own tissues – such as muscle and the thyroid gland – instead of producing protective antibodies that help to fight off infections and reduce allergic responses. These harmful antibodies are called autoantibodies and well-known examples of autoimmune diseases include Addison’s disease, coeliac disease, Hashimoto’s thyroiditis, myasthenia gravis and pernicious anaemia – all of which have fatigue and some other symptoms in common with ME/CFS.
Some people with ME/CFS (and Long Covid) have low levels of these autoantibodies (such as ANA/ antinuclear antibodies) as part of the immune-system dysfunction that occurs in ME/CFS. However, these findings are not sufficiently consistent, robust, or clearly linked to symptoms to say that this indicates that ME/CFS is an autoimmune disease. Neither is there any sound evidence to show that people with ME/CFS often have other autoimmune diseases – which tends to be the case with true autoimmune disease.
What can be said, in our current state of knowledge, is that there is an autoimmune component to ME/CFS in some people.

Research findings relating to autoimmunity in ME/CFS are summarised and referenced in the Research (Immunology) section of the MEA Clinical and Research Guide (available free to healthcare professionals): https://meassociation.org.uk/pbme