Abstract
OBJECTIVES: Cognitive dysfunction has been reported in 20-80% of SLE patients. Converging evidence has indicated the importance of vitamin D as a neuroimmunomodulator for cognitive function. In this study, we evaluated the relationship between vitamin D and cognitive dysfunction. METHODS: Consecutive age- and gender-matched SLE patients and healthy controls (HCs) were administered Automated Neuropsychological Assessment Metrics in this cross-sectional study. The primary outcome was the total throughput score (TTS). Anxiety and depression were measured using the Hospital Anxiety and Depression Scale (HADS). Levels of 25-hydroxyvitamin D [25(OH)D3 and total 25(OH)D] were measured using Liquid Chromatography-Tandem Mass Spectrometry. RESULTS: In total, 61 SLE patients and 61 HCs were studied. SLE patients scored significantly lower than HCs in the TTS (p = 0.004). There were no statistically significant differences in 25(OH)D3 levels, total 25(OH)D levels and total 25(OH)D deficiency between SLE patients and HCs. However, more SLE patients had 25(OH)D3 deficiency compared to HCs [12 (19.7%) versus 2 (3.3%), p = 0.003]. Deficiency of 25(OH)D3 (β = -63.667, SE = 27.456, p = 0.025), but not other vitamin D variables, independently predicted worse TTS after adjusting for age, education, gender, ethnicity, HADS-Total, duration of SLE, SELENA-SLEDAI, SLICC/ACR Damage Index and cumulative steroid dose in SLE patients. Age (β = -4.261, SE = 0.866, p < 0.001) was the only predictor of TTS after adjusting for education, gender, ethnicity, HADS-Total, vitamin D levels or status in HCs. CONCLUSIONS: Deficiency of 25(OH)D3, a potentially modifiable risk factor, independently predicted cognitive impairment in SLE patients.