Rheumatoid arthritis (RA) is a disorder related to chronic pain and inflammation in joints of the body. It is not commonly linked to the central nervous system and brain changes. However, some studies conducted on RA have reported high rates of cognitive impairment (CI) in adults with RA. This systematic review aimed to recognize and inspect the rates and types of CI in RA.

Multiple databases were explored within a time frame between 1994 to 2016 to acknowledge studies that have included: (i) adults with RA; (ii) standardized neuropsychological tests; and (iii) sufficient information to ascertain the relationship between CI and demographic, clinical and psychological factors. Out of 1,980 titles considered, 75 were retained at the abstract level, 36 at the full-text level and 15 studies in the final review. Then an assessment was made using a modified Newcastle-Ottawa Evaluation Scale, and the findings were synthesized using a narrative approach.

Results indicated that 10 out of 15 studies compared RA to other clinical and/or control groups. Based on summed effect size analyses, individuals with RA significantly underperformed on cognitive function tests as compared to the control groups; particularly on verbal function, memory and attention. Less clear differences were found between RA and other clinical groups. Some factors like demographics (age, education), clinical (disease activity) and psychological (depression) were found to be linked with CI but inconsistently so across studies. The limitations included a small and predominantly female sample, limited cognitive domain inclusion, lack of study details and management of confounding variables.

Overall, it was concluded that there exists some evidence for CI prevalence in adults with RA, but further studies are needed to confirm prevalence rates and examine potential mechanisms.