In New York, researchers are looking at a different dopamine receptor DR1. Scientists suspect that DR1, which gives a sensation of satiety when stimulated by dopamine, is a sort of check to DR2, said Dr. Marc Laruelle, an associate professor of psychiatry and radiology at the Columbia College of Physicians and Surgeons. The hope is that the ratio of DR1 to DR2 will be predictive. And then, perhaps, we will be able to identify addicts with very low levels of DR1 and give them a drug to stimulate DR1 more effectively. Perhaps as important as the issue of genetic susceptibility is the effect drugs have on the wiring of the brain.
Drugs lure people back because they tap into a very primal system in the human brain.
In essence, drugs of abuse hijack the brain circuitry that has evolved to help people find their way back to food sources or a sexual partners to reproduce, Dr. Childress said. Once people experience a pleasurable or terrible moment, the amygdala helps the brain remember how it got that feeling and how to get it or avoid it in the future. Normally this would drive them into a frenzy of excited anticipation. People with severe amygdalar damage quite literally have difficulty staying alive. They will cross the street in front of oncoming cars, as the normal signals for fear have been undone.