Background/Purpose: Memory impairment is prevalent in systemic lupus erythematosus (SLE), however the pathogenesis is unknown. In a previous functional Magnetic Resonance Imaging (MRI) study we demonstrated altered brain activity dynamics and less brain deactivation in patients with SLE without overt neuropsychiatric manifestations as compared to healthy controls, when performing a learning and memory task. Our findings localized this impairment to the anterior medial prefrontal cortex of the default mode network (DMN). In addition altered networking of the hippocampal subsystem of the DMN was seen in patients with SLE when performing this task. These findings may reflect compensatory mechanisms to overcome memory impairment. The purpose of the present study is to search for a structural substrate for the abnormal recruitment pattern observed in the functional MRI studies using Diffusion Tensor Imaging (DTI).

Methods: Using a DTI sequence in a 3.0T MRI scan, we characterized brain diffusivity in ten SLE patients and nine healthy controls. We examined two tracts associated with the DMN: the corpus callosum and the cingulum.

Results: In the left cingulum fibers higher apparent diffusion coefficient (ADC, F_(1,16) = 4.9, p<0.05) and radial diffusivity (Dr, F_(1,16)=4.6, p<0.05) values were seen in SLE patients as compared to controls. Similarly, in the corpus callosum, higher ADC  values (F_(1,16)=13, p<0.005), radial diffusivity (Dr )(F_(1,16)=7.4, p<0.05)  and longitudinal diffusivity (Da) ( F_(1,16)=14.4, p<0.005) were evident in SLE patients.

Conclusion: Higher diffusion coefficients in the corpus callosum and the left cingulum may indicate impaired organization / reduced integrity of these tracts which may underlie the abnormal pattern of brain activity recruitment of the DMN observed during a verbal learning and memory task. The abnormal findings in the left cingulum are in line with the central role of the left hippocampus in verbal memory and suggests that these findings may contribute to the impairment seen in patients with SLE on performance of a verbal memory task.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/impaired-diffusion-tensor-imaging-findings-in-the-corpus-callosum-and-cingulum-may-underlie-impaired-learning-and-memory-abilities-in-systemic-lupus-erythematosus/