Definition of Addiction
The American Psychiatric Association defines addiction using five criteria, tolerance, withdrawal, loss of control, preoccupation, and continuation despite adverse consequences. An addict will display three or more of the criteria.
Mechanisms of Addiction
Nicotine stimulates the release of the brain's neurotransmitters (messenger chemicals.) An increase in neurotransmitters creates a heightened alertness and aids short-term memory. The first rush of nicotine hits the brain within a few seconds. The amount of nicotine in the blood begins falling rapidly as soon as the user stops smoking or chewing. Within 45 minutes of using, the concentration of nicotine in the blood is at about half of its peak. The user begins to feel withdrawal symptoms, like irritability and restlessness. The withdrawal drive the user to smoke or chew again.
Over time, the tobacco user’s brain becomes accustomed to a certain concentration of nicotine in the blood, and tolerance builds. Users’ brains actually trick them into maintaining a set level of nicotine. Studies have shown that smokers who switch to lower nicotine cigarettes subconsciously smoke more cigarettes, inhale more deeply, hold the smoke longer, or cover the tiny holes in the filter. All of these strategies, conscious or not, increase the amount of nicotine the smoker absorbs.
The tobacco industry insisted in public for decades that nicotine was not addictive, but was "flavoring" agent. However, internal industry documents reveal the truth. Tobacco company Brown & Williamson’s general counsel wrote in 1963, "…nicotine is addictive. We are, then, in the business of selling nicotine, an addictive drug effective in the release of stress mechanisms."