Nicotine from cigarette smoke passes through the lungs into the blood and reaches the brain within a few seconds. There it binds to nicotinic receptors and increases the release of dopamine, a substance linked to feelings of pleasure and reward. This rapid effect after every puff reinforces the habit of reaching for a cigarette. The World Health Organization recognises nicotine dependence, also called nicotine addiction, as a disease and describes it in the ICD-10 classification under code F17.2 and in ICD-11 under code 6C4A.2.
In someone who smokes every day, the brain adapts to the constant presence of nicotine, and the number of nicotinic receptors grows. When the nicotine level drops, irritability, anxiety, low mood and cravings appear, and the next cigarette relieves them for a while. According to a review published in the New England Journal of Medicine, this relief of withdrawal symptoms is probably the main reason smokers feel calmer and concentrate better after a cigarette.
Withdrawal symptoms ease after a few weeks, but the urge to smoke can return for much longer. After years of smoking with coffee, after meals, with alcohol or among friends who smoke, these situations alone can trigger cravings, as can the smell of smoke or holding a cigarette. That is why the Anti-Nicotine Treatment Plan combines medication, if recommended by the doctor, with sessions in which an addiction therapist helps the patient prepare for these situations.