Adults with rheumatoid arthritis (RA) are more likely to demonstrate cognitive impairment compared with healthy adults, according to research published in the Journal of Clinical Neuroscience. Researchers highlight the potential burden of cognitive impairment in RA management.

Researchers conducted a cross-sectional, case-control study of consecutive patients to examine the prevalence of cognitive impairment and the specific factors associated with this impairment in RA.

Patients were recruited from the rheumatology unit of a university-affiliated, tertiary referral hospital between January 2016 and December 2018. Eligible patients were aged 18 years or older with an RA diagnosis based on American College of Rheumatology criteria. Patients with diagnosed dementia prior to RA diagnosis were excluded.

The final study cohort included 210 patients with RA and 70 healthy controls (83.8% and 78.6% women, respectively): Both groups were homogenous in terms of age, sex, and education level, although patients in the RA group were more likely to have hypertension, diabetes, and mood disorders.

Investigators found a statistically significant difference between the rates of cognitive impairment between the RA and control groups; 72.4% and 97.65% of patients in the RA group classified as cognitively impaired based on the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), respectively. Comparatively, only 20% and 68.6% of patients in the control group were classified as cognitively impaired (MMSE and MoCA, respectively). More patients in the RA group experienced neuropsychiatric impairment (59.5%) or subjective memory complaints (67.1%).

Mean MMSE and MoCA scores were significantly lower in patients with RA, whereas mean Hospital Anxiety and Depression Scale (HADS) Total, HADS Anxiety, and HADS Depression scores were significantly higher. Patients with RA performed significantly worse on MMSE in terms of individual analysis of cognitive domains, particularly in terms of attention, remote memory, repetition, stage command, writing, read and obey, and copy. MoCA results demonstrated statistically significant differences between RA patients and controls in almost all cognitive domains, excluding orientation.

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Patients being treated with biologic therapy were less likely to be classified as cognitively impaired according to the MMSE, whereas patients treated with oral glucocorticoid therapies and those who had positive rheumatoid factor were more likely to be classified as cognitively impaired based on the MoCA.

A linear regression analysis found that Health Assessment Questionnaire results were correlated with MMSE scores, MoCA scores, and HADS scores (r=-0.21, -0.27, and 0.46, respectively). Logistic regression analyses found that patients who were older, or who exhibited their first disease symptoms at an older age, had increased odds of being classified as cognitively impaired according to the MoCA.

Limitations to the study included the cross-sectional nature of the design, meaning that despite statistical significance, “the causal pathway to cognitive impairment could not be determined.” Additionally, this sample is not representative of all patients with RA, and therefore results may not be generalizable.

“Patients with RA may present more neurological deficits than is commonly thought,” the researchers concluded. “For persons with chronic diseases such as RA, intact cognitive function is critical for the successful performance of daily activities based on one’s current health condition … Further studies are needed to better investigate the epidemiology and the physiopathology of dementia in RA patients.”

Reference

Vitturi BK, Nascimento BAC, Alves BR, de Campos FSC, Torigoe DY. Cognitive impairment in patients with rheumatoid arthritis [published online August 22, 2019]. J Clin Neurosci. doi: 10.1016/j.jocn.2019.08.027