Some people have genes that will make it easier to become addicted to alcohol:
The feel food chemical is called dopamine
I believe u mean PEER pressure Yes it has an affect on the brain, it manipulates/pushes it to do something even if it doesn't want to. it can affect the body by harming urself from peer pressure.
if u DO mean pure pressure, as in pain, yes it has a physical affect and idk if it affects the brain.
I HOPE I HELP (ノ・ω・)ノ