"Bath salts" may have become the punchline to many bizarre crimes in recent years, but the drug is no joke: a new study has found it may be more addictive than meth. In experiments with rats, the test subjects worked much harder to get doses of methylenedioxypyrovalerone —or bath salts—than methamphetamine. The rats pressed a lever an average of 600 times for the former, and just 60 for the latter, LiveScience reports. "Some rats would even emit 3,000 lever presses for a single hit of MDPV," says study author Shawn Aarbe, per Forbes.
Of course, rats aren't humans, but "the drugs that are readily self-administered by rats tend to be the compounds that have abuse liability in humans," says one of the researchers, reports LiveScience. The rats also acted like humans do after taking bath salts, engaging in repetitive behavior akin to people grinding their teeth or picking their skin, Forbes reports. "One stereotyped behavior that we often observed was a rat repeatedly licking the clear plastic walls of its operant chamber—a behavior that was sometimes uninterruptable," says Aarde. "One could say MDPV turned some rats into 'window lickers' of a sort."