Do people freely choose to keep using drugs?

The initial decision to take drugs is typically voluntary. But with continued use, a person's ability to exert self-control can become seriously impaired; this impairment in self-control is the hallmark of addiction.

Brain imaging studies of people with addiction show physical changes in areas of the brain that are critical to judgment, decision-making, learning and memory, and behavior control.12 These changes help explain the compulsive nature of addiction.