ABSTRACT
The development of addiction involves widespread changes in reward- and stress-related brain systems. In response to repeated, greater-than-normal activation of reward circuits and suppression of stress circuits from exposure to psychoactive substances, the brain settles into an abnormal equilibrium that requires continued substance use to maintain. Withdrawal and protracted abstinence are characterized by a dampened positive emotional state and elevated negative emotional state. Initial substance use typically is driven by impulsive choices and positive reinforcement stemming from the rewarding effects of substance use. As addiction develops, substance use becomes increasingly driven by a compulsion to reduce the discomfort that occurs when substances wear off and is maintained by pathological habits and impaired impulse control. Breaking the cycle of addiction involves applying strategies that address these underlying neuroadaptations and help the brain re-establish a healthier balance. This chapter examines the brain biology and maladaptive learning processes involved in the transition from rewarded substance use behaviors to substance use disorders and implications for treatment and recovery.
