The effects of disease activity on neuronal and behavioural cognitive processes in systemic lupus erythematosus.

Objectives: Factors common across many chronic diseases, such as fatigue and depression affect cognitive dysfunction (CD) but the effect of SLE disease activity on CD remains unclear. We aimed to explore the effects of disease activity in SLE on cognitive function whilst taking into consideration other potential mediators.

Methods: Two groups of SLE patients were recruited; stable/low disease activity (SLE-S, n = 36) and active disease (SLE-F, n = 26). The SLE-F group were studied during a flare; with a second visit when disease activity had reduced. In addition to demographic, clinical and psychiatric data, CD was measured using a computerised battery of tests (CANTAB®). Functional MRI (fMRI) was used to examine neuronal responses to working memory and emotional processing tasks.

Results: No differences between the groups/visits were found using the CANTAB® battery. The fMRI results showed that the SLE-F group had a less attenuated response in the medial prefrontal cortex (a default mode network-DMN region) compared with the SLE-S group during the working memory task (P =0.012). Exploratory correlations within the SLE-F group showed associations between neuronal responses and depression, cognitive fatigue, disease activity measures and IL-6.

Conclusion: Functional brain processes but not cognitive behavioural measures were affected by disease activity. Flaring SLE patients were less able to suppress DMN regions during a working memory task. This could reflect emotional interference during cognitive tasks and may cause cognitive fatigue. A number of factors are associated with brain function in flaring patients, which has potential implications for holistic treatments.