Science Daily reports that the findings were presented at Neuroscience 2009, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.

"Our finding suggests a promising therapeutic strategy for cocaine addiction, for which there is no approved treatment," said lead author Khaled Moussawi of the Medical University of South Carolina in Charleston.

Cocaine is a highly addictive drug characterized by frequent cravings for the drug, which lead to relapses. Recent advances in brain imaging are helping scientists uncover what happens in the brain when an addicted person is exposed to the drug-associated "cues" that trigger craving and lead to relapse. They’ve found that repeated exposure to psychoactive drugs such as cocaine causes an imbalance in the brain circuits regulating reward and cognitive control.

One of these circuits is a pathway involving the neurotransmitter glutamate. In the current study, Moussawi and his colleagues found that NAC restored normal functioning to this circuit in rats that had been previously addicted to cocaine. In addition, after receiving NAC, the previously cocaine-addicted rats did not reengage in drug-seeking behavior, even in the presence of drug-associated cues.

"Clinical trials involving people addicted to cocaine and nicotine have already suggested that N-acetylcysteine may be useful in decreasing cravings for those drugs," said Moussawi. "Our research adds support to that suggestion." A phase III clinical trial using NAC to treat cocaine addiction is currently underway.

Research was supported by the National Institute of Drug Abuse.

The compound, called NNK, is a chemical substance that becomes carcinogenic when it is altered by the metabolic processes of the body. NNK does not appear to harm brain cells directly, but it may cause neuroinflammation, a condition that leads to disorders such as Multiple Sclerosis.

“Considering the extreme economical and disease burden of neuroinflammation-related disorders, it is extremely important from a medical, social, and economic point of view to discover if NNK in tobacco causes neuroinflammation” said Ghosh.

The team conducted two types of tests—one outside of a living host in glass and one in laboratory mice. They used blot analysis techniques that showed that the introduction of NNK resulted in a clear increase in proinflammatory signaling proteins, proinflammatory effector proteins, and other stress-related proteins. They also found increased levels of proinflammatory cytokines, which act as molecular messengers between cells.

This shows that NNK provokes an exaggerated response from the brain’s immune cells, known as microglia. These cells act as destroyers for the brain by attacking damaged or unhealthy cells. But when provoked by NNK, these cells start to attack healthy brain cells rather than the unhealthy ones they are supposed to attack.

NNK is present in all forms of tobacco, so it can also enter the body through chewing. In addition, second-hand smoking may lead to the same neuroinflammation conditions because NNK is also present in the smoke itself. Smoke-filled air indoors may contain up to 26 nanograms of NNK, and concentrations of NNK in tobacco can vary from 20-310 nanograms. This means that both direct and second-hand smoking can lead to substantial measures of NNK intake.

“This research sheds light on the processes that lead to nerve cell damage in those who smoke cigarettes or consume tobacco products on regular basis,” said Ghosh.

By administering injections of cocaine to a group of monkeys (who share many similar genes to that of humans) and comparing their brain functions to a control group of monkeys who did not receive drugs, scientists were able to see that several biochemical changes occurred in the monkeys who received the drugs. Simply put, the monkeys who received the cocaine injections soon developed a biological dependence on the addiction, which has given scientists and doctors new information in the battle against addiction.

According to one scientist who participated in the study, the cocaine changed the structure of neurons and protein activity, which explains why many addicts find it so hard to continue in their quest to quit drugs after a relapse. It’s an important step in realizing the kind of obstacles addicts have to overcome in the fight against addiction, and why relapse is not only likely – it should be expected. Since the experiment has shown that the brain is essentially programmed and conditioned to need the cocaine after only a few injections, it should provide doctors, therapists and society in general with a better understanding of what an addict must go through in order to win the battle against addiction.

Additionally, as many medications are developed based on the understanding of how the human brain functions, this new information is vital for research scientists and pharmaceuticals looking to develop highly effective medication to treat addictive disorders. Since popular misconceptions about addiction have indicated that abnormal brain activity leads to addiction, it’s important to realize that, very often, it’s addiction that leads to abnormal brain functions – thus, addiction should be looked at in a very new light!

This study not only has an impact on developing medicine for addicts, but it will certainly help drug education to further deter individuals from even picking up the habit in the first place. Since abusing drugs has very real long-term consequences, it’s important for drug educators to stress that quitting cold turkey will be very nearly impossible, as addiction biologically programs the brain to crave the desired drug. Thus, an addict can never “stop” whenever he or she feels like, as research has shown that relapse is practically inevitable.

This kind of research also helps to promote the theory that addiction should be treated as a disease instead of just a psychological disorder. Since debate is still raging about whether or not addiction is a disease, this study provides further evidence that addiction is founded in abnormal biochemical compositions; thus, it should be treated by doctors and scientists as a highly debilitating disease.