CI, 1.32 - 1.61).The authors noted that by chance alone, only one or two would be significant at P = .05.However, although significant, effect sizes were small."As risks go, it's a relatively small elevation," said Dr Goldacre. "Risks start to seem important at the individual patient level when they are about two-fold or over, when the risk is something like doubled."Researchers found no notable differences in the RRs for dementia after excluding cases of dementia recorded within a year of the autoimmune disease admission. This suggests that the dementia diagnosis was not the result of being admitted soon after an autoimmune disease admission.Different DementiasInvestigators subdivided patients admitted with a record of dementia into those having AD and those having vascular dementia.Of the 81,502 people with an autoimmune disease and dementia, 20,032 had a record of AD and 22,536 a record of vascular dementia. The risk for vascular dementia after an admission with an autoimmune disease was higher (RR, 1.28; 95% CI, 1.26 - 1.31) than the risk for AD (RR, 1.06; 95% CI, 1.04 - 1.08)."We think that's probably because these autoimmune diseases are themselves conditions that predispose to atherosclerotic vascular disease," said Dr Goldacre.Some autoimmune diseases were associated with an elevated risk for future vascular dementia but not AD. This was the case for RA, where the RR for vascular dementia was 1.16 (95% CI, 1.12 - 1.20) but for AD, it was 0.89 (95% CI, 0.86 - 0.93)."We might have been tempted to just dismiss the seemingly protective effect — the inverse relationship between RA and AD — were it not for the fact that others have reported on that before, so it's not an entirely sort of eccentric finding," said Dr. Goldacre.The finding helps support the hypothesis that nonsteroidal anti-inflammatory drugs (NSAIDs) protect against AD. "People with rheumatoid arthritis generally take NSAIDs to manage their condition, so if rheumatoid arthritis is at least partially a proxy for NSAID use, the real association may be between NSAID use and a reduced risk of AD," write the authors.Since dementia subgroups were not well coded on hospital records, the authors cautioned that the separate analyses of AD and vascular dementia should be viewed with caution.In analyzing the data separately for men and women, the researchers found that the adjusted RRs for dementia were broadly similar when they looked at individual diseases, but for all of them together, the RR was higher in men than women.Dr Goldacre pointed out that autoimmune diseases are generally more common in women than men. "It's often the case that the sex with the lower disease frequency has outcomes that are worse than the sex with the higher disease frequency."For example, he said, although women don't develop myocardial infarction as often as men, they tend to have a slightly higher death rate from it, he said. "I am highly speculative, but that pattern might fit here."The researchers also analyzed the data according to time interval between the autoimmune disease and dementia admissions. Most associations remained significant for 5 or more years, although they were generally stronger with shorter