Experts have associated cannabis with higher levels of THC and/or lower levels of CBD to development of dependence on the substance and a heightened risk of psychotic illness. File Photo by 7raysmarketing/pixabay

Dec. 31 (UPI) -- The potency in cannabis resin and herbal cannabis has risen, a new study says.

Researchers from the University of Bath and King's College London published a study Sunday in the journal Addiction looking at at data from 28 EU member nations, along with Norway and Turkey.


"These findings show that cannabis resin has changed rapidly across Europe, resulting in a more potent and better value product," Tom Freeman, a researcher at Bath, said in a news release.

Cannabis resin, as opposed to herbal cannabis, usually contains cannabidiol, or CBD, as well as THC. The use of CBD to treat several medical conditions like childhood epilepsy, psychosis and anxiety has risen in recent years. CBD may negate some of the harm of THC like paranoia and memory impairment.

Experts have associated cannabis with higher levels of THC and/or lower levels of CBD to development of dependence on the substance and a heightened risk of psychotic illness.

About 24 million people in Europe and 192 million people have used cannabis, the news release says.

"CBD has the potential to make cannabis safer, without limiting the positive effects users seek. What we are seeing in Europe is an increase in THC and either stable or decreasing levels of CBD, potentially making cannabis more harmful," Freeman said. "These changes in the illicit market are largely hidden from scientific investigation and are difficult to target by policy makers. An alternative option could be to attempt to control THC and CBD content through regulation."