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Lasers used to turn off cocaine addiction in rat brains, may translate into human therapy

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Neurons with light sensitive molecules
Neurons with light sensitive molecules

Kicking a cocaine addiction may be as simple as beaming a laser straight into the brain — at least in rats. That's the result of a new study of cocaine-addicted lab rodents published today by US researchers working with the National Institute on Drug Abuse. But the scientists behind it think that their results could be easily and quickly replicated in humans using a less intrusive therapy that involves stimulating the brain with magnets on the outside of the skull, and they're aiming to get human trials going by the end of the year.

"That's the most the exciting part for me," said Antonello Bonci, a research director at the National Institute of Drug Abuse who led the study, in a phone interview with The Verge. "Generally there is a 15-year-lag between the day you discover something and when you can try it in humans."

The research relies on similarities between rat and human brains

The promising new results of Bonci and his colleagues' research relies on similarities between rat and human brains, specifically an area of the rat brain known as the prelimbic cortex, which in humans is called the anterior cingulate cortex. Previous studies of human cocaine addicts have found that this area suffers from diminished activity. The researchers wanted to see if stimulating this region in addicted rats would be enough to stop cravings for cocaine.

The researchers genetically engineered the brains of a group of about 100 rats to respond to light. They took a handful of the bunch and trained them to press levers that would administer cocaine on demand. Then the researchers implanted fiber optics into these rats' brains and beamed a low-intensity laser from several feet away. While the laser was shining, rats didn't press the levers. In non-addicted rats, deactivating this part of the brain caused them to seek out cocaine. They haven't yet tested it out on other drugs, but are looking to do so in the near future.

"When we give that certain level of activity to the prefrontal cortex, the desire to take cocaine is gone."

The therapy doesn't need light to work, just a form of energetic stimulation. So researchers think that transcranial magnetic stimulation (TMS), a less invasive procedure involving placing magnets on the side of the skull, which is already being used today to treat symptoms of depression in humans, could be adapted to help cocaine addicts.

Still, there are some big unanswered questions, such as "how many times and for how long" the treatment needs to be administered to completely eliminate cravings for the drug. "We don't know that the addiction is cured," Bonci said. "All we know is that when we give that certain level of activity to the prefrontal cortex, the desire to take cocaine is gone. We can't prove that it's gone forever."