Heroin use in the US is skyrocketing. The number of people using this powerful, addictive drug has grown by nearly 300,000 in the past decade, and more and more people are dying from overdose.

But while tragic, these numbers are still outshadowed by another, equally disturbing statistic: The rise in deaths from people overdosing on powerful opiate painkillers such as Vicodin or OxyContin — the same drugs many experts have said may open the door to later heroin use.

Research suggests that one of the reasons that abusing opiates can make people more susceptible to future heroin abuse is because the drugs act similarly in the brain. A new CDC report released Tuesday found that people who abused opiate painkillers were 40 times as likely to abuse heroin.