Rheumatoid Arthritis and Cognitive Impairment or Dementia: An Updated Review of Epidemiological Data.

Rheumatoid arthritis (RA) is hypothesized to be associated with cognitive impairment and dementia, including Alzheimer's disease, through shared biological processes related to inflammation. It is important to elucidate this potential relationship as both conditions confer increased morbidity and even mortality among older adults. This narrative review provides a survey of recent epidemiologic studies, examining the association between rheumatoid arthritis and either dementia or cognitive impairment. Sixteen studies were included after searching in PubMed and EMBASE. All were published between 2012 and 2022 and were characterized as epidemiologic studies (either cohort, cross-sectional, or case-control). Studies varied in location, design, measures of exposure and outcome, and covariates considered. Of the 16 studies included, only five found statistically significant positive associations between RA and dementia or cognitive impairment. One study found an inverse relationship, while five studies found no associations at all. The remaining five studies found variable statistically significant associations between demographic or RA disease characteristics and cognitive measures. Given these mixed findings, further studies at both the mechanistic and population level are needed to clarify the possible shared biological underpinnings of these two conditions.