This study aimed to examine the relationship between the consumption of ecstasy (3,4-methylenedioxymethamphetamine (MDMA)) and cannabis, and performance on the random letter generation task which generates dependent variables drawing upon executive inhibition and access to semantic long-term memory (LTM). The participant group was a between-participant independent variable with users of both ecstasy and cannabis (E/C group, n = 15), users of cannabis but not ecstasy (CA group, n = 13) and controls with no exposure to these drugs (CO group, n = 12). Dependent variables measured violations of randomness: number of repeat sequences, number of alphabetical sequences (both drawing upon inhibition) and redundancy (drawing upon access to semantic LTM). E/C participants showed significantly higher redundancy than CO participants but did not differ from CA participants. There were no significant effects for the other dependent variables. A regression model comprising intelligence measures and estimates of ecstasy and cannabis consumption predicted redundancy scores, but only cannabis consumption contributed significantly to this prediction. Impaired access to semantic LTM may be related to cannabis consumption, although the involvement of ecstasy and other stimulant drugs cannot be excluded here. Executive inhibitory functioning, as measured by the random letter generation task, is unrelated to ecstasy and cannabis consumption.
|Journal||Human Psychopharmacology: Clinical and Experimental|
|Publication status||Published - Oct 2011|
Murphy, P., Erwin, P., Maciver, L., Fisk, J., Larkin, D., Wareing, M., Montgomery, C., Hilton, J., Tames, F. J., Bradley, B., Yanulevitch, K., & Ralley, R. (2011). The relationships of ‘ecstasy’ (MDMA) and cannabis use to impaired executive inhibition and access to semantic long-term memory. Human Psychopharmacology: Clinical and Experimental, 26(7), 460-469. https://doi.org/10.1002/hup.1228