Joh Cigarettes and alcohol are physically addictive, whereas gambling or sex addiction are mental problems
They all work with Serotonine, Dopamine, Noradrenaline, Endorphines, Phenethylamine and Oxytocine - the six chemicals that get emitted in your brain chemistry to make you become happy.
So, all in all, they work with theese.
Addiction works with theese chemicals. As soon as you take a dose of it a certain amount of at least one of those chemicals gets set free. Tabacco works in a slightly different way, too. It works with the transmittion of synapses by sendkng out an intense impulse