According to the National Cancer Institute, about 70 - 80 percent of smokers want to quit, but less than five percent of those who try to quit remain smoke-free at 12 months.
It is possible that both genetics and learned behavior affect the development of substance dependence. The concept of access certainly influences at least the type of drug used. In neighborhoods where heroin and crack cocaine are readily available, the rates are high for dependence on these drugs. Medical professionals often become dependent on prescription opiates and sedatives with anesthesiologists and nurse anesthetists generally selecting fentanyl as their drug of choice. Peer pressure is frequently cited as the reason many people experiment with drugs and alcohol. In some social sets peer pressure may result in continued abusive use but may not explain the development of dependence.