In the central nervous system (CNS), these alterations may result in reduced levels of brain-derived neurotrophic factor (BDNF), leading to glutamatergic activation and consequently triggering three major pathways of neuronal death: excitotoxicity, oxidative stress, and the induction of apoptosis [6, 55, 56], all of which contribute to cognitive decline in the aging brain. The gene discussed is BDNF; the disease is Mental deterioration.