[he0001]

I’m much older than you, and I don’t feel any of what you are describing. I’m taking on harder and harder problems, and in fact I believe I’m improving. I’m doing all R&D for my dept as none of my colleagues do/want or can do this. I’m usually the one people go to when they have problems. I haven’t used drugs, stopped drinking alcohol couple of years back and workout regularly. When I feel slow, it’s usually due to bad or little sleep.