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 in adults with RA. The objective of this systematic review was to identify and explore the rates and types of cognitive impairment in RA.
Multiple databases were searched for articles published between 1994 and 2016, to identify studies that have included: adults with RA; standardized neuropsychological tests; and sufficient information to ascertain the relationship between cognitive impairment and demographic, clinical, and psychological factors. Of 1,980 titles, 75 were retained at the abstract level, 36 at the full-text level, and 15 studies in the final review. These were evaluated using a modified Newcastle-Ottawa Scale, and the findings were synthesized using a narrative approach.
Ten of 15 studies compared RA to other clinical groups and/or a control group. Based on summed effect size analyses, individuals with RA significantly underperformed 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 and education), clinical (disease activity), and psychological (depression) factors were associated with cognitive impairment, 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.
There is evidence of cognitive impairment in adults with RA. Further studies are needed to confirm prevalence rates and examine potential mechanisms.