All leading health authorities support the three major conclusions of a 1988 report by the Surgeon General of the United States regarding nicotine and tobacco:
- Cigarettes and other forms of tobacco are addictive;
- Nicotine is the drug in tobacco that causes addiction;
- The physiological and behavioral processes that determine tobacco addiction are similar to those that determine heroin and cocaine
Nicotine fosters addiction through the brain’s “reward” pathway. Both a stimulant and a relaxant, nicotine affects the central nervous system; increases in blood pressure, pulse, and metabolic rate; constricts blood vessels of the heart and skin, and causes muscle relaxation. When nicotine is inhaled it enters the bloodstream through membranes in the mouth and upper respiratory tract and through the lungs. Once nicotine in the bloodstream reaches the brain, it binds to receptors, triggering a series of physiologic effects in the user that are perceived as a “buzz” that includes pleasure, happiness, arousal, and relaxation of stress and anxiety. These effects are caused by the release of dopamine, acetylcholine, epinephrine, norepinephrine, vasopressin, serotonin, and beta endorphin. With regular nicotine use, however, these feelings diminish and the user must consume increasing amounts of nicotine to achieve the same pleasurable effects.
Nicotine causes neurological changes that create addiction. Repeated exposure to nicotine causes neurons in the brain to adapt to the action of the drug and return brain function to normal. This process, called neuroadaptation, leads to the development of tolerance in which a given level of nicotine begins to have less of an effect on the user.
Once a brain is addicted to nicotine, the absence of nicotine causes compulsive drug-seeking behavior, which, if not satisfied, results in withdrawal symptoms including
- Difficulty concentrating;
- Increased eating;
- Heart palpitations;
- Intense cravings for nicotine.
Though smokers commonly report pleasure and reduced anger, tension, depression and stress after smoking a cigarette, many of these effects are actually due to the relief of unpleasant withdrawal symptoms that occur when a person stops smoking and deprives the brain and body of nicotine.
Nicotine causes permanent brain changes. The effects of nicotine exposure on the brain of youth and young adults include addiction, priming for use of other addictive substances, reduced impulse control, deficits in attention and cognition, and mood disorders.
Nicotine is also a carcinogen and is associated with a wide variety of very serious health issues, including:
- Various cardiovascular problems, including an increased risk of Coronary Vascular Disease by producing acute myocardial ischemia and peripheral arterial disorders;
- Various reproductive health problems;
- Immunosuppressive problems;
- Adverse effects to the heart, eyes, lungs, kidneys, and reproductive organs;
- Increased blood pressure;
- Increased risk of stroke;
- Increased risk of heart attack;
Adolescents are particularly susceptible to neurological injuries as a result of nicotine exposure. Nicotine affects neurological development in adolescents, and exposure to nicotine during adolescence produces an increased vulnerability to nicotine addiction. Adolescent nicotine addiction causes “substantial neural remodeling” including those parts of the brain governed by dopamine or acetylcholine, which play central roles in reward functioning and cognitive function, including executive function mediated by the prefrontal cortex.
Other brain changes from nicotine include increased sensitivity to other drugs and heightened impulsivity. As a result, public health authorities have concluded that e-cigarettes are unsafe for anyone under age 26.