Impact of inflammation on cognitive function in patients with highly inflammatory rheumatoid arthritis.

Objective: To evaluate cognitive function in patients with rheumatoid arthritis (RA) and inflammatory activity.

Patients and methods: We performed a cross-sectional study of a cohort of patients with RA initiating their first biological treatment due to moderate-to-high inflammation and a healthy control group (no inflammatory diseases) matched for age, sex and educational level. All participants underwent a comprehensive neuropsychological assessment, with cognitive impairment defined as a Montreal Cognitive Assessment (MoCA) score<26. Additional assessments included various cognitive tests (STROOP, forward and backward digit spans), anxiety and depression scales (Hospital Anxiety and Depression Scale), quality of life measures (Quality of Life-Rheumatoid Arthritis) and average inflammatory activity according to the 28-joint Disease Activity Score (DAS28)-C-reactive protein (CRP) into high activity (DAS28≥3.2) and low activity (DAS28<3.2) groups, also CRP levels and interleukin 6 (IL-6) levels were measured using an ELISA.

Results: The study population comprised 140 participants, 70 patients with RA and 70 controls. Patients more frequently experienced cognitive impairment than controls (60% vs 40%; p=0.019) and had lower mean (SD) values in the MoCA (23.6 (3.9) vs 25.1 (3.4); p=0.019. As for subtests of the MoCA, involvement was more marked in patients than in controls for the visuospatial-executive (p=0.030), memory (p=0.026) and abstraction (p=0.039) domains. Additionally, patients scored lower on executive function, as assessed by the backward digit span test (4.0 (1.7) vs 4.7 (1.9); p=0.039). Cognitive impairment is associated with age and a lower educational level in the general population, and among patients with RA with educational level, obesity and average inflammatory activity (DAS28, CRP, and IL-6).

Conclusions: Patients with RA with high inflammatory activity are more susceptible to cognitive impairment, which specifically affects the domains of visuospatial, memory, abstraction and executive function.