Among them, β-amyloid waterfall hypothesis is highly recognized, which suggests that the imbalance between the production and clearance of β-amyloid protein in the brain of AD patients, the aggregation to form age spots, and the mitochondrial damage induced by neurotoxicity (Yuyama and Igarashi, 2017) are the initial events of neuronal degeneration and dementia. The gene discussed is PPIB; the disease is dementia.