BDNF and Alzheimer disease: Oxidative injury, chronic activation of inflammatory pathway(s), mitochondrial impairment, vascular changes, neurotrophin(s) imbalance, protein quality control deficits and proteostasis, metal ion dyshomeostasis, genetics causes, or a combination of them are proposed to be involved in age-related disorders featured by brain and retinal degeneration, including Alzheimer’s disease (AD) and age-related macular degeneration (AMD; Kaarniranta et al., 2011; Masuzzo et al., 2016; Xu et al., 2018; Acevedo et al., 2019; Micera et al., 2019; Mufson et al., 2019; Wang and Mao, 2021).