Lasers could hold key to drug treatments

ZAPPING the brain with lasers could help researchers in the search for new treatments for drug addiction.

A study in the journal ­Nature found that stimulating one part of the brain with laser light could combat addictive ­behaviour.

The research carried out on rats also found that the lasers could turn animals who were not ­addicted into “compulsive cocaine ­seekers”.

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The researchers now hope to produce the same effect in the brains of humans, but using magnets rather than lasers.

In the new US study, involving researchers from the National Institutes of Health and the Ernest Gallo Clinic and Research Centre at the University of California in San Francisco, the team used rats bred to mimic those suffering compulsive cocaine ­addiction.

The animals, like addicted ­humans, were more likely to make bad decisions and take ­cocaine even when they had been conditioned to expect it would harm them.

Research has found that these rats have extremely low activity in the part of the brain known as the prefrontal cortex, which is fundamental for impulse control and decision making.

Other studies in humans have also found that those addicted to cocaine have a similar low level of activity in this region.

Researcher Billy Chen and colleagues used a special technique combining genetics and optics to turn the activity in this part of the brain on and off.

Light sensitive proteins called rhodopsins were inserted into the brain cells of rats in their prefrontal cortex. Targeting a laser in this region was able to turn the nerve cells on and off.

The team found that when they activated these cells they wiped out the rats’ compulsive behaviour, while switching them off turned the non-
addicted rats into addicted ones.

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Researcher Antonello Bonci said: “When we turn on a laser light in the prelimbic region of the prefrontal cortex, the compulsive cocaine seeking is gone.”

He said the most exciting aspect of the research was that there was a way to induce the same response in humans using a technique called transcranial magnetic stimulation (TMS).

Using this technique, an external electromagnetic field is applied to the brain. It has previously been used as a treatment for depression.

Clinical trials are now being designed to test whether this approach would work in addicted humans.

The researchers are planning to start trials of the technique in people addicted to cocaine.

Dave Liddell, director of the Scottish Drugs Forum, said he was “highly sceptical” of a miracle cure for cocaine dependency, but said it would be interesting to see the results of clinical trials.

“Hopefully such a trial will look at the impact on individuals beyond a narrow measure of whether or not they continue to use cocaine – looking at the person’s general well-being and functioning and whether or not they substitute cocaine with other substances including alcohol,” he said.