Rheumatoid arthritis, systemic lupus erythematosus and ankylosing spondylitis are caused by the body's immune system going wrong and causing inflammation in the joints and spine. Rheumatoid arthritis affects between 1-2% of the population, and ankylosing spondylitis between 0.5-4%. Lupus has a strong imbalance between the sexes affecting 4 per 100,000 men but over ten times (45 per 100,000) as many women. These diseases are also associated with an increased risk of mental-health problems either because of their biological effects or through the stress and anxiety they cause people. A Swedish study looked at the entire population in 1973 and again in 2004. It found that individuals with rheumatic diseases had a higher risk of psychiatric disorders than the general population with those with lupus and ankylosing spondylitis having the highest risk. Lupus carried an increased risk of dementia and delirium. Women with rheumatoid arthritis and lupus had an increased risk of psychotic disorders and severe depression.
Sundquist, Kristina ... [et al] - Subsequent risk of hospitalization for neuropsychiatric disorders in patients with rheumatic diseases Archives of General Psychiatry May 2008, 65(5), 501-507