BDNF and Alzheimer disease: 2008; Jang and Chung 2016). Drug interventions can improve the cognitive impairment observed in AD by improving synaptic plasticity in the hippocampus. Researchers have also observed a decrease in brain-derived neurotrophic factor (BDNF) and synaptic proteins in the hippocampus, including synaptophysin (SYN) and postsynaptic density protein 95 (PSD95), in stress-induced depression-like behaviour and cognitive impairment (Shen et al. 2019).