NAD+

Only gods can be immortal. When you are a god, you don't have a normal brain. You have a god brain and there are certain things you just know, or have common knowledge about.

>>19423331
What if there aren't any gods.

What if they're works of human fiction, conceived for the purpose of controlling large groups of people via hijacking their natural fear of death.

>>19423329
the brain is altered I believe

one would learn forgetfulness after the first 100 years of existence

Schwann cells, if humans had the equivalent of that and could keep building neural pathways then they wouldn't necessarily forget something that happened 100 years ago. You would forget the unimportant things to make room for healthy cells.

If someone was actually biologically immortal they would need to either keep growing somehow, either forget their old memories entirely over many years or perhaps back them up somehow on external storage