‘Bath salts’ reduce communication in rat brains

WASHINGTON — The recreational drugs known as bath salts reduce communication between different areas of the brain in rats, new research finds. This decline may be tied to the depression and aggressive behavior that some users feel after taking the drugs.

Compared with control animals, rats dosed with one bath salt variant had less synchronized activity, or “functional connectivity,” among the 86 brain areas that the researchers examined.

“The higher the dose, the less connectivity you get in the brain,” says neuroscientist Marcelo Febo, who presented the research November 15 at the annual meeting of the Society for Neuroscience. “It causes a pretty global reduction.”

Bath salts are a group of stimulants that boost levels of dopamine, a messenger molecule related to reward and pleasure, as well as norepinephrine and serotonin, which play roles in attentiveness and mood. They are chemically similar to methamphetamine, cocaine and ecstasy, and take their name from their similar appearance to the Epsom salt crystals sprinkled in bathwater.

Initially marketed as “legal highs,” the most common bath salt variants were banned in 2011. One of them,  MDPV (short for 3,4-methylenedioxypyrovalerone), is much more potent than cocaine, says Michael Baumann, a neuroscientist at the National Institute on Drug Abuse in Baltimore. “For people experimenting with this drug, if they’re used to doing a line of cocaine and they do the same-sized line of this drug, it’s essentially like they just did 10 lines of cocaine.”

Low doses of bath salts can make users feel euphoric and alert. Within hours of taking MDPV, however, some users experience a powerful crash that can make them delirious, suicidal or violent.

To investigate the lingering effects of bath salts on the entire brain, researchers gave 46 rats doses of MDPV or saline, waited an hour, and took functional MRI scans of the rats’ brains. In rats dosed with MDPV, functional connectivity decreased widely.

The findings suggest that bath salts have effects that reach beyond the dopamine reward system. “It can happen with other drugs after chronic use,” says Febo, of the University of Florida in Gainesville. He pointed out that longtime cocaine users can experience panic or anxiety after taking the drug. “But with bath salts it appears to be a much more rapid onset.”

Diminished communication between different areas of the brain may lead to the behavior that accompanies crashes, he says.

His team must still compare the effects of MDPV to those of other stimulants. Attempts to scan the brains of rats dosed with cocaine made the animals too unstable to obtain results.

Without a comparison, the data lack context, says Baumann. “They’re really big findings,” he says. “But the question is, do other stimulants do this? Or is it unique to bath salts?”

In the future, the researchers want to repeat the test with other stimulants, test rats at eight and 24 hours after being dosed with MDPV, and investigate whether the effects on connectivity match up with behavioral changes such as aggression.