People who use cocaine “recreationally” may be closer to becoming addicted than they think, a study has warned.

Even among non-dependent cocaine users, visual cues associated with consumption of the illicit drug lead to dopamine release in an area of the brain responsible for cravings, according to research published in the medical journal Scientific Reports.

Dopamine is a chemical that causes people to seek pleasurable activities, and researchers have known for years that cocaine use triggers the release of the neurotransmitter.

The research suggests that using cocaine just once may cause an addiction.

“The study provides evidence that some of the characteristic brain signals in people who have developed addictions are also present much earlier than most of us would have imagined,” said Prof Marco Leyton, an expert on the neurobiology of drug use and addictions at McGill university in Montreal, Canada.

In people with addictions, visual cues – such as seeing someone using cocaine – are often enough to trigger dopamine release.

This cue-induced release of dopamine shifts to the dorsal striatum, a structure deep inside the brain thought to be particularly important for when people start to lose control of their reward-seeking behaviours.

To better understand how soon this effect might be seen, Leyton’s team used positron emission tomography (Pet) scans to look at what happens in the dorsal striatum of recreational cocaine users.

The scientists created highly personalised cues by filming participants ingesting cocaine in the laboratory with a friend with whom they had used the drug before.

During a later session, subjects underwent a Pet scan while watching the video of their friend taking cocaine.

Exposure to the cocaine-related cues increased both craving and dopamine release in the dorsal striatum.

“An accumulation of these brain triggers might bring people closer to the edge than they had realised,” said Prof Leyton.

The findings also underscored the importance of providing help early to avoid the severe effects of dependency, he said.