Primates that aren't predisposed to addiction will become compulsive users of cocaine as the number of D2 receptors declines in their brains, Dr. Volkow noted.

The New Zealander-Australian country music star battled an addiction to cocaine in the late '90s, but cleaned up before releasing his self-titled American debut in 2000.

Additionally, the researchers saw activity in the forebrain regions known to be associated with gain and loss, addiction, cocaine cravings, addiction, and emotional regulation.