BDNF and Mental deterioration: In terms of cognitive processes, higher levels of BDNF expression have been implicated in long-term potentiation of neurons and synaptic plasticity, which may explain why higher levels of BDNF expression are associated with enhanced spatial and verbal memory and recognition capabilities, and may also counteract the effects of chronic stress and cognitive decline (Korte et al., 1995; Voss et al., 2013b; Wang et al., 2015; Liu and Nusslock, 2018; for reviews of plasticity see Lu et al., 2013, 2014; Karpova, 2014; Leal et al., 2015).