MDMA, known on the street as Molly or Ecstasy, is a popular party drug despite largely contradictory research on its dangers. Experts have long argued over the exact effects of MDMA on the brain and body — it’s been connected to several overdose deaths, but the substance may also have potential as a therapeutic drug. Recently, experts from the University of Liverpool in England consolidated past ecstasy research, and examined the effects of the drug on different parts of the brain to see if other drugs have a similar effect on the pathways MDMA disturbs.

Drs. Carl Roberts and Andrew Jones, both from the university’s Institute of Psychology, Health, and Society, teamed up with Dr. Cathy Montgomery from Liverpool John Moores University to analyze seven previous studies, all of which used molecular imaging to monitor the neuropsychological effects of ecstasy. It’s well known that MDMA significantly affects the serotonin pathway, which is involved in a staggering number of brain processes, including memory, perception, sleep, appetite, mood, and emotion.

Animal research has demonstrated that MDMA can damage serotonin-containing neurons, and previous human studies have compared ecstasy users to control groups in terms of various neuropsychological functions to determine that the drug users do indeed show changes in brain function and a higher risk of cognitive impairment. Like these studies, the Liverpool team found that ecstasy users showed significant reductions in serotonin transport in the brain — a deficit that can impact the regulation of appropriate emotional reactions to situations.

Ecstasy users also showed the greatest differences in this pathway compared to other drug users.

“Eleven out of the 14 brain regions included in analysis showed serotonin transporter reductions in ecstasy users compared to those who took other drugs,” Roberts said in a press release. “We conclude that, in line with animal data, the nerve fibers, or axons, furthest away from where serotonin neurons are produced… are most susceptible to the effects of MDMA. That is to say that these areas show the greatest changes following MDMA use.”

The authors warned that the findings are speculative, but may be important for future research into the effect of long-term chronic ecstasy use.

“It is conceivable that the observed effects on serotonin neurons contribute to mood changes associated with ecstasy/MDMA use, as well as other psychobiological changes,” Robert said. “Furthermore, the observed effects on the serotonin system inferred from the current analysis may underpin the cognitive deficits observed in ecstasy users.”

Source: Roberts C, Jones A, Montgomery C. Meta-analysis of Molecular Imagining of Serotonin Transporters in Ecstasy/Polydrug Users. Neuroscience & Behavioral Reviews. 2016.