Dementia Risk Tied to Autoimmune Disease Hospitalization

A previous hospital admission for an autoimmune disease was associated with a 20% increase in a dementia-related admission.
A previous hospital admission for an autoimmune disease was associated with a 20% increase in a dementia-related admission.

People with a history of autoimmune disease-related hospital admission are more likely to develop dementia, according to data  from a large database of hospitalizations in the National Health Service of England. The results were published in the Journal of Epidemiology and Community Health.

Previous research has linked autoimmune and inflammatory diseases to the development of dementia and Alzheimer's disease (AD), noting that AD has a similar female-to-male ratio as rheumatoid arthritis and multiple sclerosis, and an association between AD development and antithyroid antibodies.

Professor Michael J. Goldacre, MSc, FRCP, from the University of Oxford in the United Kingdom, and colleagues identified a retrospective cohort of patients admitted to the hospital with autoimmune disease using data from the Hospital Episode Statistics (HES) of England. The cohort was then analyzed  for future admissions with a diagnosis of dementia to detect possible associations between autoimmune diseases and dementia.

From 1999 to 2012, the investigators identified approximately 1.8 million hospitalizations for an autoimmune disease with a control cohort of approximately 7 million people.

Within this cohort, a history of an autoimmune disease-related admission was linked to a 20% higher likelihood of a dementia-related admission (relative risk [RR] 1.20, 95% CI: 1.19-1.21). In cases in which the dementia subtype was identified, the investigators found an RR of 1.28 (95% CI: 1.26-1.31) for vascular dementia and 1.06 (95% CI: 1.04-1.08) for AD.

In total, 18 of the 25 studied autoimmune diseases were significantly associated with dementia (18 with P <.05 and 14 with P <.001). Notably, multiple sclerosis (RR 1.97, 95% CI: 1.88-2.07), Addison disease (RR 1.48, 95% CI: 1.34-1.64), systemic lupus erythematosus (RR 1.46, 95% CI: 1.32-1.61), and psoriasis (RR 1.29, 95% CI: 1.25-1.34) were significantly associated with dementia (P <.001 for all).

Of interest, for all autoimmune diseases studied, men demonstrated a higher relative risk for dementia than women (RR 1.32 vs 1.17;

P <.001 for both). The risk of dementia was further heightened in men with MS compared with women with MS (RR 2.52, 95% CI: 2.32-2.74; P <.001 and RR 1.79, 95% CI: 1.69-1.89; P <.001, respectively).

The investigators suggest that the slightly greater risk of vascular dementia after an autoimmune disease-related admission may be tied to the association between autoimmune disease and cardiovascular disease risk factors.

The study was limited by missing cases that did not lead to an admission, as well as coding errors for the sub-types of dementia, particularly AD, which may have been miscoded or underdiagnosed.

The researchers concluded that while “people admitted to hospital with an autoimmune disease, likely to be those at the severe end of the disease spectrum, do appear to have an elevated risk of dementia,” the “findings should be considered as indicative rather than definitive.”

Reference

Wotton CJ, Goldacre MJ. Associations between specific autoimmune diseases and subsequent dementia: retrospective record-linkage cohort study, UK [published online March 1, 2017]. J Epidemiol Community Health. doi:10.1136/jech-2016-207809

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