People who have autoimmune disorders may be 20 per cent more likely to develop dementia. That’s according to an analysis of 1.8 million hospital cases in England.
Based on data collected between 1999 and 2012, the study’s findings add to mounting evidence that chronic inflammation – a common feature of many autoimmune disorders – may be a trigger of dementia and Alzheimer’s disease.
Previous studies have found that if infections or chronic inflammatory diseases – including diabetes – have pushed a person’s immune system into overdrive, this can lead to immune cells attacking healthy brain tissue.
According to the analysis, people with multiple sclerosis are among those with autoimmune disorders who are most likely to develop dementia. This finding isn’t very surprising, as the disorder is caused by the immune system attacking the central nervous system. The study, led by Michael Goldacre at the University of Oxford, found that people with the condition have double the risk of developing dementia.
But other autoimmune disorders were also associated with rises in dementia risk. The skin condition psoriasis was linked to a 29 per cent increase, while the risk of developing dementia was 46 per cent higher in people who have lupus erythematosus, a disorder that involves rashes and fatigue.
However, people with rheumatoid arthritis turned out to have around a 10 per cent lower risk of dementia. This could be because many people with arthritis take non-steroidal anti-inflammatory drugs, such as aspirin and ibuprofen, which may tame inflammation that could otherwise contribute to causing dementia.
“They reduce inflammation and that could explain why there’s less spillover, at least in principle,” says Goldacre.