The more scientists understand about the brain pathways involved in addiction, the better they can provide targets for intervention. In a review article published in the New England Journal of Medicine, three experts in the field describe three phases of addiction.
- Binge and intoxication,
- Withdrawal and negative affect, and
- Preoccupation and anticipation (or craving).
Each stage is associated with neurobiological changes in specific brain systems. During the getting high phase, the drug activates the brain's reward and motivational systems through the release of dopamine. Eventually, the person must use more of the drug to reach the same degree of pleasure.
During the avoiding the low phase, the drug influences nerve cells in the limbic system. When the drug is absent, the limbic system, which regulates emotion, sends out signals to the body to feel anxious, down and restless. The person needs the drug not to feel pleasure but to avoid feeling bad.
During the craving phase, the brain becomes obsessed with getting more of the drug. In this phase, even more changes occur in the brain, affecting how people think, learn, plan and make decisions.
With increasing knowledge about how the brain is rewired by drugs, researchers are able to develop critical therapies.