Mimicking the effects of the drug ecstasy seems to restore normal social behaviour in mice modified to have social difficulties.
聽at Stanford University in California and his colleagues have been studying sociability in mice, as a way to understand why some people with autism can find social situations unpleasant and confusing. They have found that mice missing a section of DNA are less interested in spending time with other mice. The equivalent region of human DNA is often missing in people with autism.
When mice socialise, they usually get a rush of the feel-good chemical serotonin in the brain鈥檚 nucleus accumbens. But the modified mice don鈥檛 get this serotonin surge, which may explain why they are less interested in hanging out with other mice.
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To enhance serotonin activity in the nucleus accumbens of these mice, Malenka鈥檚 team stimulated specific brain cells using laser light or a drug called CP93129. These treatments were enough to make these mice become newly sociable.
Not safe for humans
Similar treatments could potentially improve sociability in people with autism too, says Malenka.
But although the approach is promising, it is a big leap from mice to humans, says Matthew Hale at La Trobe University in Melbourne, Australia. Modified mice only mimic certain elements of autism, like reduced social motivation, rather than the whole complex condition, he says.
The techniques used by the team could not be safely used in humans, as both the drug and the laser treatments need to be applied directly to the brain.
Drugs that boost serotonin in the brain 鈥� such as the antidepressants known as selective serotonin reuptake inhibitors (SSRIs) 鈥� are already available, but these don鈥檛 seem to help people with autism. 鈥淚t might be because SSRIs only release serotonin slowly, like a dripping faucet, whereas the manipulations we did were like turning on the faucet full blast,鈥� says Malenka.
MDMA as medicine?
One drug that does flood the brain with serotonin is ecstasy. Also known as MDMA, the drug is known to make users feel loved-up and strongly connected to the people around them. It is illegal in most countries.
In mice, Malenka and his colleagues have found that MDMA exerts its pro-social effects by stimulating serotonin release in the nucleus accumbens. They are now studying whether the drug increases social behaviour in mice modified to mimic autism.
A drawback of MDMA is that it also binds to serotonin receptors in other parts of the brain and the gut and cardiovascular system, leading to side effects like insomnia, loss of appetite and high blood pressure.
However, MDMA is being trialled in people with autism already. 聽at the University of California, Los Angeles,聽and his colleagues recently conducted a trial of MDMA in 12 adults with autism. Half were given MDMA and half a placebo during two therapy sessions. Six months later, those given MDMA displayed greater reductions in social anxiety. The results will be presented at the聽聽in San Francisco this week.
Nature
Read more: Autism can bring extra abilities and now we鈥檙e finding out why
