Can nicotine and caffeine cause mental problems/disorders?

Quiting tobacco will make you live longer and make you a lot healthier. Caffeine was my Friend for years - until for some reason I was very dizzy. After a week in a hospital, and nobody had a clue, I decided to stop drinking gallons of iced tea a day because it made me pee so often. My dizziness went away. I used drink coke too. No more caffeine, and I feel a lot better.