Natural cannabis-like chemicals in the brain may help combat the leading genetic cause of autism, research has shown.
Scientists linked blockages in a signalling pathway dependent on the compounds, called 2-AG endocannabinoid transmitters, with symptoms of Fragile X syndrome.
Correcting the fault with drugs led to dramatic behavioural improvements in mice with a version of the condition.
Fragile X syndrome is the most common known genetic cause of autism.
It results from a mutation in the FMR1 gene on the female X chromosome. Men possess one copy of the chromosome, paired with a male Y chromosome, and women two.
Boys are much more likely to be born with Fragile X than girls. This is thought to be because with two X chromosomes, a defect in one may be compensated for by the other.
People with the syndrome suffer mental impairment, learning difficulties, and may be hyperactive or impulsive.
They also possess notable physical characteristics such as an elongated face, flat feet and large ears.
The scientists, writing in the journal Nature Communications, stress that while their discovery may help people with Fragile X syndrome it will not provide a cure.
“What we hope is to one day increase the ability of people with Fragile X syndrome to socialise and engage in normal cognitive functions,” said lead researcher Professor Daniele Piomelli, from the University of California at Irvine in the US.
The study was the first to identify the role of endocannabinoids in the neurobiology of Fragile X, she said.