PDYN and Anxiety: However, other opioid peptides, such as enkephalins and dynorphins, are also known to affect anxiety, aversion, and stress, all of which could be related to mood changes reported by patients using LDN (Wittmann et al., 2009; Femenía et al., 2011; Ménard et al., 2013; Melo et al., 2014; Nam et al., 2019).