Is it true that smoking changes your brain somehow, making it harder to stop smoking? If so, how does that happen? Is there anything that can be done to change it back? Yes, that's true. When you smoke, your brain changes in response to the very high levels of nicotine delivered by cigarettes.
https://newsnetwork.mayoclinic.org/discussion/smokers-brains-change-in-response-to-high-levels-of-nicotine/
https://newsnetwork.mayoclinic.org/discussion/smokers-brains-change-in-response-to-high-levels-of-nicotine/