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Wilfrid Laurier University Leaf
October 27, 2016
Canadian Excellence


Paul Mallet

Co-administration of THC and MDMA (‘Ecstasy’) synergistically disrupts memory in rats

Neuropsychopharmacology, 30, 1475 – 1482
Young, J.M., McGregor, I.S. & Mallet, P.E.

published: 2005 | Research publication | Journal article

Abstract: 3,4-Methylenedioxymethamphetamine (MDMA, ‘Ecstasy’) and cannabis are two of the most commonly used illicit drugs in the western world, and are often used in combination. Very little research has examined their effect on cognitive function or behavior when combined. The present study used a double Y-maze task to examine the acute effect of MDMA and ∆9-tetrahydrocannabinol (THC, the principal psychoactive ingredient of cannabis) on mnemonic function in rats, at a range of doses representative of common human use. Experiment 1 (low doses) examined the effect of 0.25 mg/kg THC and 1.25 mg/kg MDMA alone and together. At these doses MDMA or THC given alone had no effect on working memory, but the co-administered drugs significantly disrupted working memory. Experiment 2 (medium doses) examined the effect of 0.5 mg/kg THC and 2.5 mg/kg MDMA given alone or together. At these doses THC, but not MDMA, impaired working memory. Although MDMA alone had no effect, it exacerbated the impairment due to THC when the drugs  were co-administered. Experiment 3 (high doses) examined the effects of 1 mg/kg THC and 5 mg/kg MDMA alone and together. Both  drugs significantly impaired memory when given alone, although the impairment due to MDMA was less than that caused by THC. When co-administered at these doses, the drugs caused a major disruption of behavior and this precluded ascribing a mnemonic cause to poor  performance on the double Y-maze task. Taken together, these experiments demonstrate a synergistic disruption of working memory by acute co-administration of THC and MDMA. 

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revised Jan 20/06

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