Phil Walter/Staff

Ecstasy (MDMA) is known as the “love drug,” because it prompts cuddles, hugs and, often, a sense of deep understanding between people. Methamphetamine, meanwhile, has a much darker reputation for producing paranoid, obsessive and antisocial behavior.

But a new study suggests that — at least in low, oral doses — the effects of methamphetamine may be much more like those of ecstasy than previously believed, increasing sociability and playfulness, and belying its bad name. What’s more, the study finds that the empathetic behavior exhibited by ecstasy users may result from a reduced ability to read certain social cues, rather than any enhancement in sharing other people’s feelings. (More on Time.com: The Most Dangerous Drugs? Alcohol, Heroin and Crack — in That Order)

Published in Biological Psychiatry, the research examined the effects of MDMA, methamphetamine and placebo in four sessions with 21 healthy volunteers who were regular ecstasy users but had not previously taken methamphetamine. They reported on their experiences during each session and were also tested on their ability to read emotions in faces and voices in several tasks.

“It’s a really cool idea for a study,” says Iain McGregor, professor of psychopharmacology at the University of Sydney, who was not associated with the research. “It was surprising inasmuch as [the researchers] expected to show quite a big difference between ecstasy and methamphetamine in terms of the warm, huggy, cuddly effect.”

Instead, however, says lead author Gillinder Bedi, who conducted the research as a postdoctoral fellow at the University of Chicago, “We found that [methamphetamine] increased sociability and feelings of playfulness.” People taking ecstasy did not report any increase in feelings of sociability, but they said they felt more “friendly.” They also reported an increase in “loving” feelings, but methamphetamine users did too — just not as much. “It just didn’t reach statistical significance,” says Bedi. “But it was pretty close.” (More on Time.com: Federal Study Finds Teen Marijuana Use Up; Binge Drinking, Smoking Rates Down)

(Also, since the participants were alone in a lab during the study — and not in a big loved-up rave party — MDMA users also reported feeling lonely.)

The surprisingly benign effects of methamphetamine were probably related to dose and to the fact that it was orally administered in a safe laboratory setting, rather than taken in a less predictable environment. In fact, methamphetamine is available by prescription for use in the treatment of ADHD; when used as prescribed, it rarely produces the effects associated with street use of crystal meth.

“I really want to emphasize this,” says Bedi, “The thing with our study and with all research on [these types of drugs] is that it is highly controlled. No one is suggesting that it’s good idea for anyone to go take ecstasy or methamphetamine [on their own] to help anything.”

Dose is a key part of drug effects. “If you think about it, alcohol has different effects at different doses,” Bedi says, “You may be friendly after a couple of glasses of champagne, but at other end, you might be more likely to get into a fight when you have drunk a lot.” She adds, “At low oral doses, we saw a social enhancing effect [of methamphetamine] that doesn’t really speak to the effects of drug seen in the way that it’s typically abused.” (More on Time.com: Are Stoners Dumb—or Do They Just Think They Are?)

Methamphetamine did not affect users’ ability to read emotions in other people’s faces or voices, but MDMA did, resulting in its unexpected effect of reducing one aspect of empathy. “We found that the drug actually decreased the capacity to read negative emotion, specifically fear,” says Bedi. Reducing the detection of fearful faces might increase “empathetic” behavior — even while reducing the ability to accurately read feelings — by making people more likely to get closer to strangers, rather than maintaining distance because of fear.

“Probably part of what ecstasy does is subtly bias people towards happy faces, removing social anxiety. That all contributes towards increasing prosocial behavior and attraction to others,” says McGregor. For someone who may be prone to seeing minor negative signals of fear and anxiety in others and interpreting them as rejection, MDMA would clearly facilitate social closeness if it changed that negative bias into a positive one.

This could be useful in treatments for conditions like post-traumatic stress disorder or depression, where people have increased sensitivity to fear and rejection, respectively. “If people are less sensitive to subtle signs of negative emotion, for instance, from a therapist, that might allow you to better go into some of difficult [issues] that you didn’t want to deal with before,” says Bedi.

Part 2 of this story will explore how the hormone oxytocin may be involved in ecstasy’s cuddly effects. It will also examine why a new anti-addiction drug being tested for the treatment of autism may work by modulating oxytocin, and how oxytocin may one day even be used to treat methamphetamine addiction.

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