Neurons are genetically programmed to have long lives

Most neurons are created during embryonic development and have no ''backup'' after birth. Researchers have generally believed that their survival is determined nearly extrinsically, or by outside forces, such as the tissues and cells that neurons supply with nerve cells. Scientists have challenged this notion and reports the continuous survival of neurons is also intrinsically programmed during development.

source https://www.sciencedaily.com/releases/2020/07/200724141020.htm