Cognitive Impairment in Rheumatoid Arthritis: A Systematic Review

Objectives: Rheumatoid Arthritis (RA) is not commonly associated with central nervous system and brain changes. However a number of studies have reported high rates of cognitive impairment (CI) in adults with RA. The objective of this systematic review was to identify and explore the rates and types of CI in RA. Methods: Multiple databases were searched including a time frame between 1994 to 2016 to identify 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 psychology factors. Of 1,980 titles, 75 were retained at abstract level, 36 at full-text level and 15 studies in the final review. These were evaluated using a modified Newcastle-Ottawa Evaluation Scale and the findings were synthesized using a narrative approach. Results: Ten out of 15 studies compared RA to other clinical and/or control groups. Based on summed effect size analyses, individuals with RA significantly under-performed on cognitive function tests compared to the control groups; particularly on verbal function, memory, and attention. Less clear differences were found between RA and other clinical groups. Some demographic (age, education), clinical (disease activity) and psychological (depression) factors were associated with CI but inconsistently so across studies. A number of limitations were identified: small and predominantly female samples, limited cognitive domain inclusion, lack of study details, and management of confounding variables. Conclusions: There is evidence of CI in adults with RA. Further studies are required to confirm prevalence rates and examine potential mechanisms.