SINGAPORE: A major scientific study of children with autism spectrum disorder is set to start its final leg to test if a Melbourne-made cannabis oil reduces core symptoms of the neurological condition.

If successful the medicine’s developer, Neurotech International, says it would be one of the first approved to treat core symptoms of autism in children globally.

Around one in 40 Australians are on the autism ­spectrum, a complex neurodevelopmental condition that ­affects how a person’s brain ­develops and functions.

A smaller clinical trial of the oral cannabinoid drug, led by Monash Health, found it helped reduce symptoms such as anxiety and improved mood and cognitive engagement in 84 per cent of children within eight weeks.

This staggering result came from a clinical global impression score that measures how children improve on a therapy.

This final phase three study, also to be led by Monash Health, is recruiting 150 ­Victorian children who will ­receive either a placebo or drops of the pharmacy-grade cannabis oil twice a day.

The product is made using predominantly CBDA, rather than the more widely known chemical CBD. These are both substances from the cannabis plant, but interact differently in the body.

Study lead Michael Fahey is a professor of pediatrics at ­Monash Health and director of the Pediatric Neurology ­Department at Monash Children’s Hospital.

His team is investigating the oil’s safety and effectiveness at improving autism spectrum disorder symptoms.

Professor Fahey welcomed the results of a landmark review into cannabis oil published on Tuesday in the international journal Lancet Psychiatry. The Australian study analysed the results from 54 trials published over 45 years testing the effectiveness of medicinal cannabis for mental disorders and found there was no evidence to support medicinal cannabis treatment for most mental illnesses.

“It was a really important study,” Professor Fahey said.

“I think it speaks to what’s important across health and that is that we do good work, and we ask questions. Across the mental health space I think there’s been studies that are not high quality, so they leave you in a place where you’re not sure how to interpret the outcome correctly.”

Professor Fahey said cannabis was one area where people had made assumptions and had access to a cannabis product without it going through a high-grade clinical trial.

He said scientific studies need to be safe and scientists had to stick to the principles of doing things the right way to find out if a substance worked, or didn’t.

Professor Fahey said early data showed there was potential for this medicine.

“I wouldn’t be doing it if I didn’t think there was potential and there are so few options as far as the autism space goes,” he said. “We have treatments that we use that have side effects; we have treatments that we use that we know are problematic and they don’t work in everyone. In our pilot studies, this (medicine) was promising and it allowed us to design better trials going forward.

“We did a pilot study, we did a phase two trial and now we’re moving … into a phase three. And if you look at the study this week, that’s really what’s missing: people haven’t done high-quality trials.”

Neurotech CEO Anthony Filippis said what set the medicine apart was it was CBDA-rich and had low doses of THC, the main psychoactive ingredient in the cannabis plant.

“Our earlier trials showed clinically meaningful and statistically significant improvements in the core symptoms of autism spectrum disorder,” Dr Filippis said.