Association Between Serum BDNF and S100 B Levels in Community-Dwelling Older Adults

Population aging has made the maintenance of cognitive function and mental health in older adults a major public health priority. Brain-derived neurotrophic factor (BDNF) and S100 calcium-binding protein B (S100 B) are biomarkers of brain health, reflecting neurotrophic support and neuroinflammatory activity, respectively. The objectives of this study were to examine the association (a) between serum BDNF and S100 B levels and (b) between these biomarkers and cognitive function and depression in community-dwelling older adults. This cross-sectional study included 95 community-dwelling adults aged ≥65 years living in rural Japan. Serum BDNF and S100 B levels were measured using enzyme-linked immunosorbent assays. Cognitive function and depressive symptoms were assessed using four instruments. Spearman's correlation analyses examined associations between the biomarkers and neuropsychological measures. Multiple regression analyses were performed using log10-transformed S100 B as the dependent variable and log10-transformed BDNF, age, sex, education, and BMI as independent variables. Serum BDNF levels were negatively correlated with serum S100 B levels (β = -0.509, p < 0.0001). This association remained significant across adjusted models (all p < 0.0001). Sensitivity analyses yielded consistent results. No associations were observed between serum BDNF or S100 B levels and cognitive function or depression. The inverse relationship between BDNF and S100 B suggests a link between neurotrophic and neuroinflammatory processes. Nursing interventions that enhance BDNF may also affect S100 B level, which may foster brain health in older adults.