For those who have never used drugs or experienced a dependence upon them, it is hard to understand the draw. Yet, when someone is dependent upon drugs or alcohol, the pleasure center within the brain is hijacked, which disrupts the normal functioning of its reward circuitry. Science Daily has reported on the latest research in drug and alcohol dependence. The addiction "switch" has often been studied and researchers have now implicated a naturally occurring protein. A dose of this protein allows them to get rats hooked without using drugs at all. "If we can understand how the brain's circuitry changes in association with drug abuse, it could potentially suggest ways to medically counteract the effects of dependency," said Scott Steffensen, in the Science Daily piece. Steffensen is a neuroscientist at Brigham Young University who co-authored the study with two of his undergraduate students, one of his grad students, and a team of researchers at the University of Toronto. An increase of a naturally occurring protein called BDNF can occur in chronic drug users' reward circuitry in the brain. This is the region that scientists call the ventral tegmental area. In this study, researchers directly infused extra BDNF into this part of the brain in rats and found that it made the rats behave as though they were dependent on opiates, even though they never received the drug. The research team found that this protein is a critical regulator of drug dependency. After the BDNF injection was received, specific chemicals that would normally inhibit neurons in this part of the brain instead excited them. This is the "switch" that is known to occur in people when they become dependent on drugs. The findings from this research suggest that BDNF is crucial for inducing a drug dependent state. If continued research supports this theory, it could help to introduce new treatment methods for those who have a drug or alcohol dependence problem.