Nicotine and related disorders Causes and symptoms How nicotine works Nicotine is the main addictive drug among the 4,000 compounds found in tobacco smoke. Such other substances in smoke as tar and carbon monoxide present documented health hazards, but they are not addictive and do not cause cravings or withdrawal symptoms to the extent that nicotine does. Nicotine is both a stimulant and a sedative. It is a psychoactive drug, meaning that it works in the brain, alters brain chemistry, and changes mood. Once tobacco smoke is inhaled, nicotine passes rapidly through the linings of the lungs and into the blood. It quickly circulates to the brain where it indirectly increases the supply of dopamine, a chemical in the brain that affects mood. Dopamine is normally released in response to pleasurable sensations. Nicotine, like cocaine or heroin, artificially stimulates the release of dopamine. This release accounts for the pleasurable sensation that most smokers feel almost as soon as they light up a cigarette. Nicotine also
This is the end of the preview. Sign up
access the rest of the document.