Advances in medical imaging have revealed that addiction is a complex disease of the brain, said NIDA director Dr. Nora Volkow.
“By understanding how addiction affects different neuronal processes, we can gather insights that give us a better understanding of why the behaviors of people who are addicted are so disruptive to their lives and frequently that of others,” said Volkow at the Clinical Center’s Contemporary Clinical Medicine: Great Teachers Grand Rounds Lecture held recently in Lipsett Amphitheater.
What nearly every abused drug that results in addiction—whether it be cocaine, alcohol, opioids or nicotine—has in common is not only that they activate the reward circuit of the brain but also that their repeated use modifies the function of the prefrontal cortex. The prefrontal cortex, which is necessary to exert self-regulation and to assign saliency value to stimuli in the environment, doesn’t develop fully until the mid-twenties. The prefrontal cortex, in coordination with the reward circuit, fuels behaviors “that are indispensable for survival.” If a person is hungry, procuring food becomes a salient motivating behavior and eating is experienced as rewarding. Normally, people stop thinking about food once they’ve eaten and food loses its incentive value, which is assigned by the ventral component of the prefrontal cortex (orbitofrontal cortex).