Serum brain-derived neurotrophic factor levels as a novel biological marker for the activities of psychiatric symptoms in systemic lupus erythematosus

Abstract

Objectives. Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious but potentially treatable disease. However, biological markers such as IgG index or IL-6 do not always reflect the severity of the psychotic symptoms of NPSLE. We hypothesized that serum BDNF levels may be a biological marker for reflecting the severity of the psychiatric symptoms of NPSLE. Methods. The participants enrolled in this study were 28 healthy volunteers and 54 Japanese SLE inpatients at the University Hospital of Occupational and Environmental Health, all of whom fulfilled the criteria for the classification of SLE. SLE patients were divided into the three groups: NPSLE with psychiatric symptoms including an acute confusional state, anxiety disorder, cognitive dysfunction, mood disorder, and psychosis (NP group); NPSLE without psychiatric symptoms (NN group); and SLE without neuropsychiatric symptoms (S group). The serum BDNF levels were measured by ELISA. Results. Serum BDNF levels were significantly increased in the NP group (mean ± SE = 37.0 ± 5.46 ng/ml) compared with those in the other three groups (NN group; mean ± SE=9.1 ± 2.44 ng/ml, P < 0.0001, S group; mean ± SE=10.4 ± 2.51 ng/ml, P < 0.0001, healthy control; mean ± SE= 11.44 ± 0.69, P < 0.0001). Subsequently, serum BDNF levels were decreased in parallel with the improvement of psychiatric symptoms in the NP group. Conclusion. These results suggest that serum BDNF is a biological marker for the severity of psychiatric symptoms in NPSLE patients.