There are many biological factors that are involved with the addicted brain. "The addicted brain is distinctly different from the nonaddicted brain, as manifested by changes in brain metabolic activity, receptor availability, gene expression, and responsiveness to environmental cues" (2) In the brain, there are many changes that take place when drugs enter a person's blood stream. The pathway in the brain that the drugs take is first to the ventral tegmentum to the nucleus accumbens, and the drugs also go to the limbic system and the...