Neurocognitive performance following acute mephedrone administration, with and without alcohol

Mephedrone, a recreational drug similar to MDMA, impairs short-term spatial memory one hour after intake but improves critical tracking performance four hours later. When combined with alcohol, mephedrone reduces reaction time compared to alcohol alone, but does not counteract alcohol's impairing effects on divided attention or spatial memory. Alcohol alone impairs both short- and long-term spatial memory and divided attention. The findings suggest mephedrone enhances psychomotor performance while harming memory, and its stimulatory effects are insufficient to offset alcohol-induced deficits on most cognitive tasks.

Study at a glance

Abstract

Recreational use of mephedrone, alone and in combination with alcohol, has increased over the past years. Pharmacological properties of mephedrone share similarities with methylenedioxymethamphetamine (MDMA), but its effect on neurocognitive function has not been well established in humans. The present study assessed the effect of mephedrone alone and after co-administration with alcohol on neurocognitive function. It was hypothesised that mephedrone would improve psychomotor performance but impair memory performance, when administered alone. Neurocognitive performance was expected to be impaired following mephedrone when combined with alcohol. Eleven participants received single doses of 200 mg mephedrone or placebo combined with 0.8 g/kg alcohol or placebo. Neurocognitive performance was assessed at baseline (T 0 ), at one hour (T 1 ) and four hours after (T 2 ) mephedrone administration, by means of the Divided Attention Task (DAT), Critical Tracking Task (CTT), and the Spatial Memory Test (SMT). Mephedrone intoxication impaired short-term spatial memory at T 1 and improved critical tracking performance at T 2 . Mephedrone alone did not affect divided attention, but did show an interaction with alcohol on reaction time at T 2 . Reaction time decreased when mephedrone was combined with alcohol as compared to alcohol alone. Alcohol intoxication impaired both short- and long-term spatial memory at T 1 and divided attention at T 1 and T 2 . Critical tracking performance was not affected by alcohol intoxication. The current findings support the hypothesis that mephedrone improves psychomotor performance, impairs spatial memory and does not affect divided attention performance. Stimulatory effects of mephedrone were not sufficient to compensate for the impairing effects of alcohol on most performance parameters.