Purpose: Neurocognitive: To compare executive function in ecstasy users and non-user controls, and to further explore the nature and pattern of executive function in abstinent ecstasy users.

Design: Non-experimental (retrospective) 2-group between subjects design, with drug use (ecstasy use versus no ecstasy use) serving as a between-group factor, with all participants completing a measure of executive function.

Subjects: 24 ecstasy users and 24 non-user controls residing in the Toronto (Ontario) area and recruited via word of mouth (self-referred). Matching - Groups were matched on gender and education, and approximately matched on age.

Criteria for Inclusion, Ecstasy Users - Having used ecstasy at least once (measured as occasions). Non-Users - Never having used ecstasy, but use of other drugs permitted. Both Groups - Not pregnant, no past or current major medical or psychiatric illness, as assessed through medical interview, no current alcohol dependence, absence of current dyslexia, migraine or eating disorder, and fluent English-speaker. Abstinence from all psychoactive drugs for at least 2 weeks prior to the study day, with abstinence verified through urinalysis on study day. Having reported sleeping for 7-9 h each night for at least a week prior to study day.

Drug Use Parameters - Ecstasy Use - Average lifetime ecstasy use, reported as number of times used, was 31.21 times (range 1-150 times), with average dose per use being 1.21 tablets (Range = 0.5 - 2.5 tablets). Average duration of use, in months, was 23.88 months (Range = 3 - 72 months), and average frequency of use, as number of times used per month, was 1.91 uses per month (Range = 0.5 - 6 per month). Average time since last use, in days, was 118.7 days (Range = 14 - 1092 days). Other drugs - Use of each drug is reported as any prior use across lifetime. Cigarettes had been used by 20 / 24 ecstasy users and by 8 / 24 non-user controls. Alcohol had been used by 23 / 24 ecstasy users and by 15 / 24 non-user controls. 12 / 24 ecstasy users reported having used amphetamines, and 1/24 of non-users reported using amphetamines. Cocaine had been used by 6/24 ecstasy users and by none of the non-users. 1/24 ecstasy users and 1/24 non-users used anti-depressants. Sedatives and hypnotics were used by 1/24 ecstasy users and by 1/24 non-user. LSD had been used by 8/24 ecstasy users and by 1/24 non-user. 23/24 ecstasy users had used cannabis, and 9/24 non-users had used cannabis. Neither group reported having used solvents/inhalants or opiates. 4/24 ecstasy users reported using PCP or related drugs, and no non-users reported using these drugs. With the exception of alcohol, it does not appear that the two groups were matched on use of other drugs.

Group Demographics and Matched Variables - While the authors do not explicitly state variable matching, it appears that ecstasy users and non-users were matched on gender, education and (approximately) on age. Gender, as M/F ratio - Ecstasy users, 16/8: Non-user controls, 16/8. Age - On average, ecstasy users were 22.96 years old (range = 18-34) and non-users were 19.54 (Range = 17-26). Education, measured in years of education attained. Ecstasy users attained 14.54 years education (Range = 13-16 years), and non-user controls attained 14.33 years education (Range = 14-17). Other Variables - The proportion of ecstasy users reporting use of every other legal and illicit drug was greater than the proportion of non-user controls reporting use of the same drug.

Measures: Executive Function - Measured through the Behavioral Assessment of Dysexecutive Syndrome (BADS), containing 6 sub-tests. These are Rule Shift Cards (similar to WCST), Action Program (devise set of steps to solve problem, number of steps completed recorded), Key Search (measures efficiency of search strategy), Temporal Judgment (estimation of time required for four common events), Zoo Map (visit specific locations by following rules, number of correct sites visited and number of rules broken recorded) and Modified Six Elements Task (Organization in accordance to rules and restrictions, (presumably categorical), and number of tasks completed, number of rules broken and time taken to complete task recorded).

Analyses: Raw scores for each sub-test were transformed into profile scores (values 0-4), and these were summed to produce a total profile score. Sub-test profile scores and total profile scores were analyzed via between group ANCOVA, with drug-use (ecstasy use versus no ecstasy use) serving as a between-group variable and participant's age serving as a covariate. Effect size was also calculated for each sub-test and for total Profile Score.

Drug Use Parameters and BADS Test Performance - Associations between parameters of ecstasy use (number of times used, duration of use, average dose per use and frequency of use, and perhaps a "dose" variable and BADS scores were analyzed via correlational analyses (Pearson's product-moment). Dose score was calculated as average dose per use x frequency of use.

Results - Significant Differences: Executive Function - Ecstasy users had a lower total profile score than non-user controls. Significant differences in sub-test performance were found for Modified Six Elements and Temporal Judgement, with ecstasy users having lower scores than non-users on these sub-tests. The highest effect sizes were for Modified Six Elements Task and total profile score, followed by Rule Shift and Temporal Judgment.

Drug Use Parameters and BADS Test Performance - Lifetime use of ecstasy (in number of times used) was inversely (negatively) correlated with Modified Six Elements, Rule Shift and Action Program (poorer performance seen with increase in number of times ecstasy was used). Duration of ecstasy use was inversely associated with performance on Modified Six Elements, Action Program and Rule Shift, with longer duration of use associated with poorer performance on these tests. Usual dose per use, in tablets, was inversely associated with Rule Shift, with higher usual dose associated with poorer performance. Frequency of use was inversely correlated with Rule Shift and Temporal Judgment, with more frequent use associated with poorer performance. Lifetime use (occasions), duration of use and average dose per use were also inversely correlated with total profile score.

Results - No Differences Found: Executive Function - Ecstasy users and non-users did not show significant differences in test performance on the Rule Shift, Action Program, Key Search or Zoo Map sub-tests of the BADS. The lowest effect sizes were for differences in the Key Search sub-test, followed by Zoo Map and Action Program.

Drug Use Parameters and BADS Test Performance - There were no significant associations between any parameter of ecstasy use (number of times used, average dose per use, duration of use, frequency of use or time since last use) and performance on the Key Search or Zoo Map sub-tests. Time since last use was not correlated in any way with performance on any BADS sub-test, or with total profile score. None of the drug use parameters (Number of occasions, average dose per use, duration or frequency of use) were correlated with Key Search. Lifetime number of uses (occasions), duration of use and average dose per use were not associated with Temporal Judgements or Zoo Map. Average dose per use was not associated with performance on Action Program or Modified Six Elements. Frequency of use was not associated with performance on Action Program, Modified Six Elements or Zoo Map sub-tests. Frequency of use was not associated with total profile score, though it was associated with 2 of 6 BADS sub-tests.

Overall Effects: When age was controlled for (via serving as covariate), ecstasy users matched on gender and education were found to have significantly lower scores on all but one sub-test of executive function when compared with an equal number of non-user controls. Specifically, ecstasy users fared less well on tests of organization and use of categorization (Modified Six Elements Task) and a test of time estimation for common events (Temporal judgements). The overall BADS scores were lower for ecstasy users than for non-users. Effect sizes (measures degree of inter-group difference versus overlap) for each test ranged from small to large, with many being medium. Larger effect sizes were also found for group differences in Modified Six Elements and Temporal Judgment tasks, as well as Total Profile Score. All drug use parameters except for time since last use were significantly and inversely correlated with at least one sub-test of the BADS. While number of times used, duration of use and average dose per use were all inversely correlated with BADS profile score, neither time since last use nor frequency of use were correlated with total profile score. (It is possible that the authors did not use time since last use in their analyses). The Rule Shift test was inversely correlated with number of times used, average dose per use, duration of use and frequency of use, though there were no significant differences in Rule Shift scores for ecstasy users and non-users. Number of times used, duration of use and average dose per use were inversely correlated with Action Program scores (also despite the lack of significant differences between performance by ecstasy users and non-users). Modified Six Elements scores were inversely related to number of times used and duration of use, and Temporal Judgements scores were only inversely correlated with frequency of use.