The researchers studied three genetic markers, and the material they collected could point to reasons why some people became dependent on the drug.
Lead researcher Dr Chandni Hidocha of UCL's Clinical Pharmacology Unit said the team had looked at whether the three markers could predict addiction-related responses, such as the extent to which one's attention was drawn to cannabis-related pictures.
The researchers investigated three different markers of genetic variation — all involved in the body's endocannabinoid system — that had been previously suspected to have a role in cannabis addiction; however, all three had not been considered in a single study.
"They were tested for drug cue salience (which means how attention-grabbing cannabis-related images were versus neutral images, such as side-by-side images of a woman smoking cannabis and a woman holding a pen near her mouth); a satiety measure (testing whether they still wanted more cannabis after they'd already had some) and a craving measure. They were also tested for the three genetic markers," the study said.
"Differences to drug cue salience and state satiety were found for all three genetic variants. One genotype, regarding the Cannabinoid receptor 1 gene, was associated with people continuing to want more cannabis after having used it, and continuing to be more drawn to cannabis-related imagery while under the influence."
The researchers said this suggested that people with that genetic marker could be more prone to cannabis addiction, especially as tetrahydrocannabinol, the psychoactive component in cannabis, binds to this receptor.
"There's still more work to be done to clarify how these genetic variants impact drug effects, and to identify what other factors should be considered to gauge how vulnerable someone is to cannabis addiction," the study's senior author, Professor Val Curran of the UCL Clinical Psychopharmacology Unit, said.
"With time, we hope that our results could pave the way towards more personalised approaches to medicinal cannabis prescription."