E-cigarettes, designed to help people quit smoking, could act as a "gateway" to trying more harmful illicit drugs, researchers claim.
Like conventional cigarettes, the devices, which contain "pure nicotine", are said to raise the addiction to banned substances such as cannabis and cocaine.
In tests on mice, US neuroscientist Professor Eric Kandel found they developed a need for cocaine and warned this could have the same effect in humans.
The effects of using of e-cigarettes is stronger in adolescents than adults, experts claim.
Professor Eric Kandel, whose research suggests E-cigarettes could lead to harder drug use, said: "The effects we saw in adult mice are probably even stronger in adolescent animals.
"One drug alters the brain's circuitry in a way that enhances the effects of a subsequent drug. Therefore, we should do all we can to protect young people from the harmful effects of nicotine and the risks of progressing to illicit drugs."
More than a million people in the UK are believed to get their nicotine fix from e-cigarettes but opinion is divided about the safety of them.
The first E-cigarette dates back to 1963 in Pennsylvania when a 40-a-day smoker filed for a patent "smokeless non-tobacco cigarette".
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.