Antibodies against N-methyl-D-aspartate receptors in patients with systemic lupus erythematosus without major neuropsychiatric syndromes

Abstract

Purpose Approximately 14–54% of patients with systemic lupus erythematosus without a history of major neuropsychiatric syndromes (nonNPSLE) have cognitive deficits. Elevated N-methyl-D-aspartate (NMDA) receptor antibodies (anti-NR2) have been reported in 35% of patients with SLE, but few studies have utilized controls or a composite memory index. We hypothesized that serum anti-NR2 would be elevated in nonNPSLE compared to healthy controls, and that elevated anti-NR2 would be associated with memory dysfunction and depression. Methods Subjects included 43 nonNPSLE patients with a mean age of 36.5 (SD = 9.0) and mean education level of 14.7 years (SD = 2.5). Twenty-seven healthy control subjects with similar demographic characteristics were also enrolled in this study. A global Cognitive Impairment Index (CII) and a Memory Impairment Index (MII) were calculated using impaired test scores from the ACR–SLE neuropsychological battery. Serum samples were analyzed using a standard ELISA for anti-NR2. Results Elevations of serum anti-NR2 were found in 14.0% of the nonNPSLE and 7.4% of the controls ( p = 0.47). There was no relationship between elevated anti-NR2 status and higher CII or performance on the MII. No relationship between levels of depressive symptoms and anti-NR2 was found. Conclusions The frequency of elevated anti-NR2 was low (14.0%) in this sample of SLE patients and not significantly different from controls. A relationship was not found between the presence of anti-NR2 in serum and global cognitive or memory indices, or with depression. Results suggest that serum anti-NR2 is not likely related to mild cognitive dysfunction in SLE patients without a prior history of NPSLE.