Proportion, domains, and risk factors of cognitive impairment in systemic lupus erythematosus

Cognitive impairment (CI) in systemic lupus erythematosus (SLE) is quite common and is an important prognostic factor due to its severity. The aim of our study was to determine the proportion and type of CI in SLE and to identify associated risk factors.

We performed a cross-sectional study (January - March 2022). Participants included SLE patients and controls (No-SLE). SLE patients were subdivided into those with and those without CI to identify associated risk factors. CI was defined based on the results of eight specific tests assessing various cognitive functions, with MMSE used for overall cognitive assessment. Impairment was indicated by abnormalities in at least five of these eight functions.

Our study included 60 lupus and 40 non-lupus participants. The median disease duration of patients in the SLE group was 72 months (interquartile range: 24 - 150 months). The proportion of cognitive impairment in SLE was 31.7%. The comparative study of cognitive functions between the two groups of participants with and without SLE concluded that executive functions and verbal fluency were more impaired in the lupus group compared to the non-lupus group. It also concluded that there were no statistically significant differences in attention and concentration, episodic memory, working memory, calculation, visuospatial and visuoconstructive activity, or judgement. In the multivariate analysis, patients with SLE have a significantly higher risk of CI (Adjusted OR 3.76, 95% CI: 1.217 - 11.621) compared to non-SLE individuals. Each additional year of age increases the risk by 4.4% (Adjusted OR 1.044, 95% CI: 1.008 - 1.082). For factors associated with CI in SLE, the multivariate analysis concluded that the duration of corticosteroid therapy, by months, had an adjusted OR equal to 1.009 (CI (95%): 1.000-1.018), and the duration of education, by years, had an adjusted OR equal to 0.857 (CI (95%): 0.736-0.999).

Screening for CI in lupus patients is important, especially for those with factors associated with these disorders such as prolonged duration of corticosteroid therapy and shortened schooling.