Two years ago, Antonello Bonci, a researcher at the National Institute on Drug Abuse, published a study in the journal Nature. After making rats so addicted to cocaine they’d brave electric shocks to get their fix, Bonci’s team stimulated the rats’ brains with a relatively new technique called optogenetics.
The treatment introduces light-sensitive proteins into the brain, then activates the proteins with light beams. The light stimulated the rats’ prefrontal cortex, the part of the brain most associated with addiction, and afterwards, the rats showed less interest in cocaine.
Shortly thereafter, a newspaper in Bonci’s small hometown in northeastern Italy published an article about the work. A man whose son struggled with cocaine addiction and suicidal thoughts saw the article and wondered, could this be something that could work in humans? He went to talk to a researcher at the University of Padua in Italy, who agreed the work sounded promising.
Optogenetics is still relatively new and has only ever been tested on animals. But researchers believe transcranial magnetic stimulation (TMS), which is known to be safe on humans, works by stimulating the brain in a similar way. Physicians at the University of Padua thought perhaps TMS could be used on humans with a similar effect that optogenetics has on rats.
With Bonci as a collaborator, the doctors in Padua spearheaded a new study that looked at the effects of TMS on cocaine's cravings. Subjects received treatment using a small, figure eight-shaped magnetic device placed near the skull, which delivered painless pulses to the brain on five consecutive days, followed by once-a-week treatments for three weeks. Though small—it only enrolled 29 subjects—its results have generated excitement in the addiction treatment community. Out of the 13 subjects who received an all-TMS protocol, 10 showed “significant improvement” in terms of craving.
“I have met with these patients, I have seen them, I have seen their families,” says Bonci, a co-author on the study. One of the participants was the addict who had desperately tried to end his life. “They are alive, they are well…something has clearly happened to these people,” he says.
TMS, which has been around for about three decades, is largely used for treatment-resistant depression. But in recent years, a number of studies have looked at its use in treating other disorders, including OCD, Parkinson’s, epilepsy and migraine, with somewhat mixed results. A growing body of research suggests TMS may have applications for various kinds of addictions and addictive behaviors, including alcoholism, smoking and binge-eating. Though most of the studies have been very small, results have been generally positive.
No one knows exactly how TMS works—perhaps it stimulates production of certain neurotransmitters, like dopamine, or maybe it enhances neural connectivity. In the case of addiction, it may “scramble” the brain’s craving signals. And it’s still unclear whether TMS will be just as effective when tested on larger and more diverse populations. The Italian study, for example, used mostly Caucasian men. In addition, the participants were all “treatment seekers,” meaning they were motivated to get better and potentially more subject to placebo effect.
“This is a pilot study—we have a lot of work to do,” Bonci says. He is currently in the process of launching a much larger, placebo-controlled, double-blind study of cocaine addicts. “I think that we will know, in just a few years, if this will become an accepted treatment [for a variety of addictions],” he says.
While there were once few medical options for addicts, there are now a number of drugs aimed at preventing cravings or reducing the neural reward for using. Still, many of these drugs have side effects. Topiramate/Topamax, used to reduce alcohol cravings, is sometimes nicknamed "Stupamax" for making users dopey and forgetful. Other drugs, such as methadone, used for treating opioid addiction, must be used for a long period of time. TMS is largely free from reported side effects, barring the occasional headache.
“I think this is just an extraordinary time,” Bonci says. “To be able to speak with patients and hear ‘if I am alive, it is because of your rodent study’—nothing beats that.”