Does medication ruin your brain or can it go back to normal?

[deadendgame]

I'm asking this because I'm about to start a new job which requires mental as well as physical ability. I don't know if I will be able to do this due to all the medications I have taken in the past. I taken them in large amounts. Also, I drink caffeine everyday multiple times a day. Coffee energy drinks everything. I also smoke alot of cigarettes. Will I be able to hold this new job at all or will it just be an uphill battle for me? Thanks for your response.

 

[LuGoJ]

What kind of job? They are all different
What is expected of you? Every job has difference requirements
What medication? There are thousands of medications. Are you talking about a tylenol once a week or Thorazine and haldol benders every day?
How does the caffeine effect you? I know I can't be quiet, focus and sit still if i'm hopped up on caffeine and energy drinks.
Does your job allow smoke breaks? My last job only had a short lunch break and didn't allow other breaks. As a result, heavy smokers had a very difficult time there and didn't last very long.