The answer to this perplexing question spans basic neurobiological, psychological, social, and environmental factors. The repeated use of addictive drugs eventually changes how the brain functions. Resulting brain changes, which accompany the transition from voluntary to compulsive drug use, affect the brain’s natural inhibition and reward centers, causing the addicted person to use drugs in spite of the adverse health, social, and legal consequences (Baler and Volkow 2006; Volkow et al. 2010; and Chandler et al. 2009). Craving for drugs may be triggered by contact with the people, places, and things associated with prior drug use, as well as by stress. Forced abstinence (when it occurs) is not treatment, and it does not cure addiction. Abstinent individuals must still learn how to avoid relapse, including those who may have been abstinent for a long period of time while incarcerated.

Addictive drugs can cause long-lasting changes in the brain: PET scans showing glucose metabolism in healthy (normal) and cocaine-addicted brains. Even after 100 days of abstinence, glucose metabolism has not returned to normal levels.

Potential risk factors for released offenders include pressures from peers and family members to return to drug use and a criminal lifestyle. Tensions of daily life—violent associates, few opportunities for legitimate employment, lack of safe housing, and even the need to comply with correctional supervision conditions—can also create stressful situations that can precipitate a relapse to drug use.

Research on how the brain is affected by drug abuse promises to teach us much more about the mechanics of drug-induced brain changes and their relationship to addiction. Research also reveals that with effective drug abuse treatment, individuals can overcome persistent drug effects and lead healthy, productive lives.