Patients with systemic lupus erythematosus (SLE) without overt neuropsychiatric symptoms displayed impairment of working spatial memory and cognitive dysfunction during an ethological assessment compared with matched control patients, according to recent research published in The Journal of Rheumatology.1
Chun-Min Zhu, MD, department of radiology, First Affiliated Hospital, Medical College of Shantou University, Guangdong Key Laboratory of Medical Molecular Imaging, and Graduate School of Beijing Normal University in Zhuhai, China, and colleagues identified 18 patients with SLE who did not have neuropsychiatric SLE (NPSLE) as classified by the American College of Rheumatology.2
The non-NPSLE patients and 18 matched control subjects underwent the Montreal Cognitive Assessment (MOCA) scale test, blood-oxygen-level dependent (BOLD) functional MRI (fMRI), and n-back tests to assess function, memory, and activation intensity of cognition-related areas.
High-Yield Data Summary
- Defects in spatial working memory and mild cognitive dysfunction related to right dorsolateral prefrontal cortex-posterior parietal lobe and parahippocampal gyrus damage were identified by functional MRI imaging in patients with non-neuropsychiatric SLE.
In subtests for naming or orientation, there were no significant between-group differences in MOCA-Chinese revised (MOCA-CR) performance; however, there were significant between-group differences regarding language subsets, visuospatial/executive assessment, attention assessment, and total scores ( P <.01) as well as memory and abstraction subtests (P <.05).
While all patients demonstrated a memory-related load effect in accuracy and reaction time when increasing from 0-back to 2-back tasks, there was a significant difference in accuracy during 2-back tasks (P =.002) but not during 0-back tasks (P =.505) or 1-back tasks (P =0.319).
Dr Zhu and colleagues reported significantly different reaction times in both groups for all n-back tasks (F = 169.26, P <.0001), but there was a larger difference in patients with SLE during the 2-back task.
The researchers found the bilateral dorsolateral prefrontal cortex (DLPFC), parietal lobe, premotor area (preMA), supplementary motor area (SMA), and anterior cingulate cortex (ACC) formed a right hemisphere dominating neural network during the n-back tasks, with patients with non-NPSLE showing only a right SMA/ACC load effect and lower activation of spatial working memory (WM)-related brain areas in the 3 memory load tests.
“Further, we found that the activation intensity of some cognition-related areas, including the bilateral caudate nucleus/insula and hippocampus/parahippocampal gyrus were lower than the control group under the memory loads,” Dr Zhu and colleagues wrote in their study.
Summary & Clinical Applicability
“To our best knowledge, this is the first study using MOCA-CR, the n-back task, and BOLD-fMRI technology to investigate the spatial WM function and the brain activity network of non-NPSLE patients,” Dr Zhu and colleagues wrote in their study. “The findings showed that spatial WM was processed by a network of frontoparietal lobe and subcortical structures.”
The researchers noted that there was an inverse association between individual activation intensity and disease duration, and predicted that longer disease duration could correlate with increased central nervous system damage among patients with non-NPSLE.
“[Non-NPSLE patients] already have WM hypofunction, and the miopragia of the DLPFC/[parietal area]/PreMA network might be one of the neural mechanisms responsible for this spatial WM impairment,” the researchers wrote.
- Researchers noted a small study population limited the results, and future studies should include more neuropsychological tests to improve cognitive assessment of patients
This study was sponsored by grants from the National Natural Science Foundation of China, Natural Science Foundation of Guangdong Province of China, Science and Technology Planning Project of Guangdong Province of China, Shantou Technology Bureau Science Foundation of China, and Shantou Government Technology.
Zhu, C-M, Ma Y, Xie L, et al. Spatial working memory impairment in patients with non-neuropsychiatric systemic lupus erythematosus: A blood-oxygen-level dependent functional magnetic resonance imaging study. [published online January 15, 2017] J Rheumatol. 2017; doi: 10.3899/jrheum.160290.
The American College of Rheumatology nomenclature and case definitions for neuropsychiatric lupus syndromes. Arthritis Rheum. 1999;42:599-608.