BDNF and post-traumatic stress disorder: The effects of exercise on enhancing extinction learning and augmenting exposure therapy in PTSD also involves neurochemical events involving the endocannabinoid system (Marsicanoet al., 2002), dopaminergic signalling (Cisleret al., 2020;Cuiet al., 2020;Esseret al., 2021), BDNF (Notaras & van den Buuse, 2020), and mammalian rapamycin (Moyaet al., 2020).