Memory issues, here. I didn’t think I would have bad memory issues until just a while ago, I had a thought on the tip of my nose, but forgot it in seconds and how it took me minutes to recall it. That’s a key sign right there.
Some people have better memory in old age, like it’s unreal sometimes with what some of them can remember. While the average person forgets thoughts in moments.
Aging. I didn’t expect to live through my twenties due to a reckless lifestyle that included lots of drugs and partying and rubbing shoulders with questionable types of people. I saw an old lady being helped walking with a younger woman at age ~27 and went, oh shit. That might be me one day. I had severely chilled out and converted to a more typical lifestyle by then.