Furthermore, the synbiotic-treated group showed a significant negative correlation between BDNF and Parts I, II and III of the MDS-UPDRS, which reflects the role of BDNF in alleviating symptoms of PD, since BDNF was reported to maintain neuronal plasticity and adaptation to environmental challenges (Scalzo et al. 2010a; Bathina and Das 2015; Geng et al. 2023). This evidence concerns the gene BDNF and Parkinson disease.