BilZ0r
Bluelight Crew
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Evidence for executive deficits among users of MDMA (Ecstasy).
Br J Psychol. 2004 Nov;95(Part 4):457-466.
Fisk JE, Montgomery C, Murphy P, Wareing M.
[Abstract]
This article was posted on PubMed in the last couple of hours, so it must be rather new indeed.
Basically, they use a relatively large sample group: (44 current Ecstasy users, and 59 non-Ecstasy users), which are very similiar demographically:
___________________________Users________Non-users
________________________Mean___SD____Mean___SD__p
Age_____________________21.52__1.66___21.37__1.84__ns
Years of education_________15.66__2.23___15.29__2.16__ns
Ravens Progressive Matrices_48.77__5.94___47.95__5.11__ns
NART____________________28.91__6.88___30.05__5.72__ns
Ravens Progressive Matrices is basically a complete the series, kinda question you'd see in an IQ test. Here is an example.
NART is a reading test. So as you can see, the groups are quite equal as far as age, education, 'IQ' and reading skill.
The using group is composed of quite heavy users (Typical Britons)
Weeks since last used_______10.90
Length of use (weeks)_______183.27
Total number of tablets taken_343.38
Current use: times per week__0.44
Average (tablets per week)___2.14
The two tests were Random Letter generation, and computation span tests. The random letter generation test goes like this: The participant asked to speak aloud a letter each time they heard an auditory signal. Participants are asked to produce letters in a random sequence avoiding alphabetical or well-known sequences They were asked to avoid generating alphabetical sequences and repeat sequences such as AB or BBC. They are also asked to try to produce each letter with the same overall frequency. (It's surprisingly hard). The measure is how many overly redundant letters they used (i.e. if they had to give 260 letters, then they should give each letter 10 times).
The computation span test Participants were presented with a number of arithmetic problems (e.g. 4 + 7=) They were required to solve each problem as it was presented (by circling one of three multiple-choice answers), while at the same time remembering the second digit of each presented problem. At the end of each set of problems the second digits had to be recalled in the order in which they were presented. The measure is how many errors in recall.
Apposed to previous results, using smaller samples, Ecstacy users perfromed just as well as non-users in the Random Letter Generation Task. But, even after trying to account for high cannabis and cocaine user, ecstacy users performed worse on the computation span test.
In their conclusion, the authors state "Because the current study failed to find an Ecstasy-related deficit on the random generation task the available evidence suggests that Ecstasy may not be associated with any substantial impairment in this aspect of executive processing...
...Previous studies from our laboratory have revealed Ecstasy-related deficits in working memory span (e.g.Wareing, Fisk, Murphy, & Montgomery, 2004). However, controls for the use of other illicit drugs were not as extensive as those employed in this study... ...Thus, the current study offers the clearest evidence to date that Ecstasy users are impaired on one specific aspect of executive functioning, updating, and this deficit, at least in part, appears to be independent of the potential effects of other illicit drugs."
Unfortunately, this study doesn't look at abstinant users.
The full paper may be found here (102k).
Br J Psychol. 2004 Nov;95(Part 4):457-466.
Fisk JE, Montgomery C, Murphy P, Wareing M.
[Abstract]
This article was posted on PubMed in the last couple of hours, so it must be rather new indeed.
Basically, they use a relatively large sample group: (44 current Ecstasy users, and 59 non-Ecstasy users), which are very similiar demographically:
___________________________Users________Non-users
________________________Mean___SD____Mean___SD__p
Age_____________________21.52__1.66___21.37__1.84__ns
Years of education_________15.66__2.23___15.29__2.16__ns
Ravens Progressive Matrices_48.77__5.94___47.95__5.11__ns
NART____________________28.91__6.88___30.05__5.72__ns
Ravens Progressive Matrices is basically a complete the series, kinda question you'd see in an IQ test. Here is an example.
NART is a reading test. So as you can see, the groups are quite equal as far as age, education, 'IQ' and reading skill.
The using group is composed of quite heavy users (Typical Britons)
Weeks since last used_______10.90
Length of use (weeks)_______183.27
Total number of tablets taken_343.38
Current use: times per week__0.44
Average (tablets per week)___2.14
The two tests were Random Letter generation, and computation span tests. The random letter generation test goes like this: The participant asked to speak aloud a letter each time they heard an auditory signal. Participants are asked to produce letters in a random sequence avoiding alphabetical or well-known sequences They were asked to avoid generating alphabetical sequences and repeat sequences such as AB or BBC. They are also asked to try to produce each letter with the same overall frequency. (It's surprisingly hard). The measure is how many overly redundant letters they used (i.e. if they had to give 260 letters, then they should give each letter 10 times).
The computation span test Participants were presented with a number of arithmetic problems (e.g. 4 + 7=) They were required to solve each problem as it was presented (by circling one of three multiple-choice answers), while at the same time remembering the second digit of each presented problem. At the end of each set of problems the second digits had to be recalled in the order in which they were presented. The measure is how many errors in recall.
Apposed to previous results, using smaller samples, Ecstacy users perfromed just as well as non-users in the Random Letter Generation Task. But, even after trying to account for high cannabis and cocaine user, ecstacy users performed worse on the computation span test.
In their conclusion, the authors state "Because the current study failed to find an Ecstasy-related deficit on the random generation task the available evidence suggests that Ecstasy may not be associated with any substantial impairment in this aspect of executive processing...
...Previous studies from our laboratory have revealed Ecstasy-related deficits in working memory span (e.g.Wareing, Fisk, Murphy, & Montgomery, 2004). However, controls for the use of other illicit drugs were not as extensive as those employed in this study... ...Thus, the current study offers the clearest evidence to date that Ecstasy users are impaired on one specific aspect of executive functioning, updating, and this deficit, at least in part, appears to be independent of the potential effects of other illicit drugs."
Unfortunately, this study doesn't look at abstinant users.
The full paper may be found here (102k).