Chemicals that activate the reward system are reinforcing to a wide variety of species from reptiles to humans. Their physiological activation of brain reward systems is believed to be the starting point for the neurobiological changes that launch the addiction trajectory. Research on addiction has started to uncover the sequence of events and long-lasting sequelae that can result from the persistent abuse of addictive substances. These studies have shown how repeated drug use can target key molecules (both common and specific for various drug types) and brain circuits, and eventually disrupt the higher order processes that underlie emotions, cognition, and behavior, and enable an individual to exert self-control. Specifically, preclinical and clinical brain imaging studies have shown that addiction is characterized by an expanding cycle of dysfunction in the brain. The impairment appears to start in the more evolutionarily primitive areas that process reward, but then moves on to other brain regions that are responsible for more complex cognitive functions. Thus, in addition to reward, addicted individuals can experience severe disruptions in learning (memory, conditioning, habituation), executive function (impulse inhibition, decision making, delayed gratification, judgment), cognitive awareness (interoception), and emotional response (mood and stress reactivity). The combined, cumulative impact of addiction on all these circuits results in poor decision making in addicted individuals despite awareness of negative consequences, and the inability to delay gratification despite future losses. Scientific advances in this area are informing strategies for medication development to help buffer the brain dysfunction associated with chronic drug exposure and addiction.

• Dialogue 27
  11 sessions
• October 30, 2013
  Dharamsala, Himachal Pradesh, India
• Session Audio
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