A new study has found a direct correlation to drug addiction and brain levels of serotonin, which could potentially spark a revolution in addiction treatment.

Sarah Bradbury, who will receive her PhD this week in Psychology, found that a person’s serotonin levels in their first experiences with using drugs play a critical role in whether they will become addicted. She suggests that serotonin levels also begin to decrease once drug use becomes more frequent. Although her research was focused on MDMA and cocaine use, Bradbury said her findings translate to a broader range of drug addictions.

"People develop drug addiction due to changes in specific brain systems following repeated drug use, but not all drug users become addicted," she explained. "Another brain chemical, dopamine, seems to be the critical determinant of drug addiction during this phase.”

Her findings are similar to other recent research projects. A December 2011 study from researchers at Vanderbilt University found a correlation between recreational ecstasy use and sustained increases in serotonin receptor density, which can lead to major serotonin depletion and severe depression once the drug exits a person’s system.

Ronald L. Cowan, MD, PhD, explained to The Fix that this damage to serotonin receptors is permanent, even if a person stops using the drug. Although some scientists use ecstasy as a means of treating autism and post-traumatic stress disorder, Cowan said it’s a different situation than simply using it for fun.

“If you have kids taking this drug and going out dancing or having sex, these behaviors increase the risk of raising the body temperature,” he said. “There’s a difference between using the drug recreationally and using it therapeutically, at a low dose in a controlled setting.”

Dopamine levels have also been linked to susceptibility to addiction. A study published last July in the journal Proceedings of the National Academy of Sciences found that chronic marijuana use dampened the brain’s dopamine reaction to stimulants, which means they could experience less of a reward or motivation from things that most people find pleasurable. Contrary to the stereotypes of marijuana use, however, it could also leave them feeling more irritable, moody and restless.