Clinical associations of cognitive dysfunction in systemic lupus erythematosus

Abstract

Objective Cognitive dysfunction in SLE is common, but clinical risk factors are poorly understood. This study aims to explore the associations of cognitive dysfunction in SLE with disease activity, organ damage, biomarkers and medications. Methods We performed cross-sectional cognitive assessment using a conventional neuropsychological test battery, with normative values derived from demographically matched healthy subjects. Endpoints included two binary definitions of cognitive dysfunction and seven individual cognitive domain scores. Clinical parameters included disease activity (SLEDAI-2K) and organ damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index). We performed regression analyses to determine associations between clinical parameters and cognitive endpoints. Results 89 patients with SLE were studied, with median age of 45 and disease duration of 15 years. Organ damage was significantly associated with severe cognitive dysfunction (OR 1.49, CI 1.01-2.22) and worse cognitive test performance in three of the seven individual cognitive domains. In contrast, no significant associations were found between SLEDAI-2K at the time of cognitive assessment and any cognitive endpoints on multivariate analysis. Higher time-adjusted mean SLEDAI-2K was associated with better verbal memory scores but had no significant associations with other cognitive endpoints. The presence of anti-dsDNA antibodies and high IFN gene signature were negatively associated with severe cognitive dysfunction; there were no significant associations with the other autoantibodies studied or any medications. Substance use was significantly associated with lower psychomotor speed. Only 8% of patients who had cognitive dysfunction on testing had been recognised by clinicians on their SDI score. Conclusions In SLE, cognitive dysfunction was positively associated with organ damage, but not associated with disease activity, and serological activity and high IFN signature were negatively associated. Cognitive dysfunction was poorly captured by clinicians. These findings have implications for preventative strategies addressing cognitive dysfunction in SLE.