What do cigarettes do to your brain?

Answer 1

The give you a Psychological affect that makes you addicted.
Here is a link about what Nicotine can do to you,
http://wso.williams.edu/orgs/peerh/drugs/nicotine.html

Answer 2

Hardening and narrowing of the arteries due to roughness of the arterial wall attracting deposits of cholesterol. It's true of all the vasculature in the body, not just the brain.

Answer 3

There is an old but true saying : " No two objects can occupy the same space at the same time". When you inhale smoke you are not inhaling the oxygen that your body needs and it lowers the immune system.