Mephedrone Decreases Memory, Increases Depression, Craving

Deborah Brauser

January 18, 2012

January 18, 2012 — Despite considerable cognitive side effects associated with the street drug mephedrone, many young adults in the United Kingdom (UK) continue to use the synthetic stimulant, new research shows.

In a small study of 40 young adults, regular users of mephedrone had increased rates of psychosis, depression, and cognitive impairment compared with their non-using peers. Mephedrone was also associated with increased craving and "binge-style" usage.

"We predicted that craving or 'wanting' mephedrone would be elevated when users were intoxicated, and our results supported this hypothesis," lead author Tom P. Freeman, PhD candidate in psychopharmacology in the Clinical Psychopharmacology Unit at the University College London, told Medscape Medical News.

Tom Freeman

"However, I was surprised by the extent of bingeing that we found in this high functioning, predominantly student sample," said Mr. Freeman.

He added that approximately half of the mephedrone users reported using the drug repeatedly during a typical session until they had completely run out of product; the average session length was almost 8 hours across the whole group.

The investigators note that the mephedrone users also reported that fewer side effects and positive reviews from friends would be key components in switching to a "new legal high."

"Factors that influence users' attitudes to new drugs might help to predict future trends in use of the many new psychoactive substances emerging on the Internet," the investigators write.

The study was published January 18 in Addiction.

"Unprecedented Rise" in Use

Mephedrone (which is also known as 4-methylmethcathinone, meow-meow, MCAT, bubbles, and drone) is one of the ingredients in "bath salts." Until its reclassification in 2010 by UK officials as a Class B drug, it was legal and easily found online under the description "plant food."

According to the investigators, there was "an unprecedented rise" in the drug's consumption throughout Europe in 2009, leading to the reclassification and decision that mephedrone needed to be better controlled throughout the European Union (EU).

"Despite these changes, the drug is still available through street dealers at high prices and also online," write the researchers.

"Mephedrone was almost unheard of prior to 2008 but by 2010 had become the second most popular drug amongst 16 to 24 year olds and equal to cocaine, according to the 2011 British Crime Survey," said Mr. Freeman.

"Since this study was the first to document the acute and long-term effects associated with mephedrone use in humans, it presented itself as an important public health issue."

The investigators enrolled 20 individuals (55% men; mean age, 21.6 years) who reported using mephedrone more than 2 times a month and 20 "healthy control participants" (70% men, mean age, 21.6 years).

Increased Craving

Both groups were evaluated twice (one week apart) in their homes. The drug users were first assessed while they were intoxicated with their own mephedrone; they were assessed again when they were drug free for at least the previous 24-hour period.

The control groups reported having tried mephedrone once before but not in the previous 6 months. Both of their assessment periods were while they were drug free.

Measurements used included the visual analogue scale (VAS) to evaluate want and feelings about the drug, the Beck Depression Inventory, the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) to assess trait schizotypy, and the Mephedrone and Future Use Questionnaire.

Cognition was assessed using the Rivermead Behavioral Memory Test (for prose recall), a spatial N-back test, a trailmaking test, and the Wechsler Test of Adult Reading. Phonological and semantic fluency were also evaluated.

Results showed that for the mephedrone group, a typical use session lasted almost 8 hours (mean, 7.65 hours; ± 4.55 hours); they persons in that group typically consumed 1.06 g per session. All reported administering the drug through the nose.

The mephedrone group also had significantly worse prose recall scores (P = .037) and significantly higher scores in depression (P = .01), total schizotypy (P < .001), and cognitive disorganization (P = .001) compared with the healthy control participants.

In addition, according to results from the VAS, "mephedrone acutely primed a marked 'wanting' for the drug (P < .001)," report the investigators.

Not Benign

Mephedrone users also had higher scores than healthy control participants in impulsive nonconformity (P = .02) on the O-LIFE, which correlated with the number of hours in an average use session.

"Those who were more impulsive tended to self-administer the drug over a longer period of time than more self-controlled individuals," said Mr. Freeman.

Finally, since mephedrone became illegal, 100% of respondents reported they now purchased it on the street; 65% reported a decrease in the quality of the drug; and 55% reported increased use of other illicit drugs.

When choosing a new substance for getting high, study participants cited purity, no long-term or short-term side effects, positive endorsement by friends or from the Internet, and that it was legal.

A lack of research on a particular drug was not a strong deterrent. Media interest in the drug was cited as the least important factor.

"Now that mephedrone is illegal, users are looking for a new legal high and are basing their decisions on unreliable sources," said Mr. Freeman.

The investigators report that there were 41 new substances detected in the European Union in 2010, 15 of which were synthetic cathinones.

"The toxicity of these new drugs should be investigated, as well as larger scale studies looking at why young people might be attracted to try new substances," said Mr. Freeman.

He added that clinicians need to understand that mephedrone is not a benign substance and that more studies are needed to examine its effect in humans, "as it may be a long-term addition to the illicit drugs market."

The study authors have disclosed no relevant financial relationships.

Addiction. Published online January 18, 2012. Abstract


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