Memory impairment associated with neurometabolic abnormalities of the hippocampus in patients with non-neuropsychiatric systemic lupus erythematosus

Objective: Memory impairment is common in patients with systemic lupus erythematosus (SLE). This study examined hippocampal volumes and neurometabolic alterations in relation to memory function in SLE patients without a history of neuropsychiatric syndromes (nonNPSLE).

Methods: Subjects included 81 nonNPSLE patients and 34 healthy controls. Volumetric magnetic resonance imaging and magnetic resonance spectroscopy of the right and left hippocampal areas (RH, LH) were performed. Verbal and visual memory tests were administered and a Memory Impairment Index (MII) was derived from standardized tests.

Results: Higher memory impairment (MII) was correlated with lower RH glutamate + glutamine/creatine (p = 0.009) and lower RH N-acetylaspartic acid/creatine (p = 0.012) in nonNPSLE patients. A trend for a negative correlation between RH and LH volumes and MII was evident for absolute hippocampal volumes. Lower RH glutamate + glutamine/creatine was also correlated with worse performance in a mean visual memory index (p = 0.017).

Conclusions: An association between reduced memory and lower N-acetylaspartic acid/creatine in the RH suggests neuronal damage in nonNPSLE patients with very mild and early disease. Alterations in glutamate + glutamine/creatine further indicate early metabolic changes in nonNPSLE are related to memory impairment, a finding that might suggest that memory impairment relates to presynaptic glutamatergic dysfunction in the hippocampus.