Associations between long-term changes in serum BDNF and oxytocin levels in older adults: A 10-year follow-up study

Objectives This longitudinal study investigated the relationship between serum brain-derived neurotrophic factor (BDNF) levels—measured at baseline, follow-up, and as 10-year changes—and serum oxytocin levels at follow-up in community-dwelling older adults in rural Japan. Methods A total of 46 participants (mean age at baseline = 69.54 ± 4.11 years) who completed assessments at both baseline (2005–2007, T1) and follow-up (2016–2017, T2) were included. Serum BDNF and oxytocin levels were measured using enzyme-linked immunosorbent assays. Cognitive function was assessed with the Mini-Mental State Examination, Frontal Assessment Battery, and Clinical Dementia Rating. Results Results indicated a significant increase in serum BDNF levels over the 10-year period. Pearson’s correlation analysis revealed no significant association between BDNF levels at T1 and T2. Notably, both BDNF levels at T2 and the 10-year change in BDNF (ΔBDNF: T2−T1) were significantly and positively correlated with oxytocin levels at T2. These associations remained robust after adjusting for age, sex, and years of education in multiple regression models. However, no significant associations were observed between changes in BDNF and changes in cognitive function scores over the same period. Conclusions These findings suggest that higher or increasing BDNF levels over time may be linked to elevated oxytocin levels in older adults, providing preliminary biological evidence of an association between long-term BDNF dynamics and oxytocin regulation in older adults. Given the observed association between BDNF and oxytocin signaling, further research is warranted to elucidate the underlying mechanisms and their implications for cognitive and mental health in aging populations.