The direct path from log10 BDNF to hippocampal atrophy was not significant, while the direct paths from age and education to hippocampal atrophy were significant (β = 0.321, p < 0.001 and β =  − 0.188, p = 0.004, respectively), as had been shown in our previous study20. Here, BDNF is linked to hippocampal atrophy.