Monoamine oxidase inhibitors [1] which are present in cigarettes seem to greatly contribute to the nicotine addictiveness. See this literature review from Gwer

Monoamine oxidase inhibitors [1] which are present in cigarettes seem to greatly contribute to the nicotine addictiveness. See this literature review from Gwern for more information. [2] [1] https://en.m.wikipedia.org/wiki/Monoamine_oxidase_inhibitor https://en.m.wikipedia.org/wiki/Monoamine_oxidase_inhibitor [2] https://www.gwern.net/Nicotine#addictiveness https://www.gwern.net/Nicotine#addictiveness