MDMA (Ecstasy, Molly) and mephedrone are two illegal\/illicit substances that act as stimulants in the human body. Some recreational drug users\/abusers treat these two substances as equivalent and interchangeable. However, according to the results of a study review published in March 2014 in the British Journal of Pharmacology, people who treat mephedrone as an MDMA substitute subject themselves to serious potential negative consequences. These include the onset of intense mephedrone withdrawal symptoms and a possible increase in the odds of ultimately developing a physical dependence on drug intake. \r\nThe Basics\r\nMDMA is a \u201cclub drug\u201d that combines the central nervous system effects of stimulant drugs and medications with some of the perceptual changes produced by hallucinogenic substances. Specific effects associated with intake of the drug include blood pressure and heart rate increases, a sometimes-steep rise in body temperature, feelings of expansiveness and changes in both normal touch and normal light sensitivity. Some sources report that the form of MDMA known as Molly has fewer impurities than the form of the drug known as Ecstasy. However, since MDMA is not made in monitored conditions, no one knows for sure if these claims accurately describe any real-world differences. Some users of MDMA experience at least one of the known symptoms of substance addiction: continued consumption of the drug despite exposure to significant negative outcomes related to that consumption. Mephedrone is one of the most common ingredients found in the relatively new illegal\/illicit drugs known as \u201cbath salts.\u201d Like the other typical active ingredients contained in these drugs, it belongs to a group of chemicals called synthetic cathinones, which resemble both MDMA and the stimulant amphetamine. Mephedrone increases the normal rate of activity in the central nervous system just like amphetamine, cocaine and other stimulant drugs and medications. In addition, it produces hallucinations similar to those associated with the use of MDMA or classic hallucinogens like LSD. Some drugs users knowingly substitute mephedrone for MDMA under certain circumstances; others may unknowingly use substances that, although sold as MDMA, actually contain mephedrone or some other synthetic cathinone.\r\nConsequences of Substitution\r\nIn the study review published in the British Journal of Pharmacology, researchers from Great Britain\u2019s University of Nottingham used an analysis of previous studies to compare the impact of MDMA use to the impact of mephedrone use. The researchers also looked at what can happen when a given individual uses mephedrone as a substitute for MDMA. Some of the studies under consideration involved laboratory experiments on animals, while others involved clinical experiments on human beings. After completing their analysis, the researchers came to several important conclusions. First, they concluded that both MDMA and mephedrone produce largely similar short-term health risks in users; however, users of MDMA have specific risks for developing a dangerously high body temperature, as well as for experiencing certain toxic reactions inside the brain. The researchers also concluded that, for a number of reasons, people who use mephedrone may have a higher chance of developing the symptoms of physical drug dependence than users of MDMA. These reasons include mephedrone\u2019s relatively strong mind-altering effects inside the brain, the relatively short amount of time from mephedrone ingestion to the onset of the drug\u2019s effects and the relatively brief amount of time during which mephedrone triggers its peak drug impact. In combination, these characteristics may cause mephedrone users to \u201cbinge\u201d on the drug and unwittingly accelerate the brain changes required to produce physical dependence and the highly dysfunctional behaviors associated with drug addiction. The researchers also concluded that the rapid activity of mephedrone inside the brain may also make users of this drug susceptible to the symptoms of drug withdrawal. As a rule, drug withdrawal occurs when a person affected by physical dependence does not receive enough of the drug in question to meet the brain\u2019s expectations and established requirements. Since mephedrone\u2019s effects don\u2019t last for long, users of the drug may experience unusually intense withdrawal symptoms.\r\nSignificance and Considerations\r\nThe authors of the study review published in the British Journal of Pharmacology note that the results of their analysis indicate that mephedrone differs substantially from other types of synthetic cathinones, as well as from MDMA. However, altogether, their work reinforces the growing scientific consensus that use of bath salts can lead to the eventual development of diagnosable symptoms of drug addiction. Since some drug users knowingly or unknowingly substitute mephedrone for MDMA, they may also increase their chances of developing serious addiction-related problems.