Purpose: Neuropsychological, behavioral: to compare ecstasy users and non-user controls on objective (laboratory) measures of aggression, and to investigate relationship between neuroendocrine profile and cardiovascular measures to aggression. Specific hypothesis Tested - that aggressive responses in the laboratory would increase with duration of use or lifetime ecstasy dosage.

Design: Retrospective (non-experimental) between-subjects design, with ecstasy use (present or absent) as the between-subjects variable. All participants underwent a laboratory procedure intended to induce aggression, and blood samples were drawn from all participants.

Subjects: 12 male ecstasy users (ages 18-29, mean = 24 +/- 3.55) and 20 male non-drug user controls (ages 19-32, mean = 26.4 +/- 6.5), with ecstasy users recruited after they initiated contact with substance abuse treatment clinic in Parma (Italy), and non-drug user controls recruited from hospital staff (not working in the substance abuse wing) in Parma. Matching - Ecstasy users were matched with non-users on gender, age and education.

Criteria for Inclusion, Ecstasy Users - Having used ecstasy on at least 50 occasions, male, having sought treatment or requested information about ecstasy or other drug use, self-reported minimal use of substances other than ecstasy, alcohol and nicotine, abstinence from ecstasy for three weeks prior to study days, with abstinence verified via urinary analysis 3 times each week.

Non-user controls - Never having used ecstasy, being male and matching ecstasy users in age, unclear whether use of drugs in lifetime permitted or not (previous studies only permitted use of legal psychoactives), abstinence from all psychoactive substances for 3 weeks prior to study day, with abstinence verified by urinary analysis (carried out either weekly for 4 weeks, or once 4 weeks before study days). Being hospital staff, but not employed at drug abuse treatment clinic. Both Groups - Healthy, as established via medical and psychiatric examination and laboratory analyses.

Drug Use Parameters - Ecstasy users had taken an average lifetime use of 77.9 +/- 23.51 tablets (range = 50-150 tablets), with an average dose per use of 1 to 2 tablets per use (variance of MDMA content in pills found in local area, 25 - 125 mg). Information on frequency of use not clearly stated, but apparently average use was no more than twice per week (on weekends), and no less than once a year, with implied use seeming to 4 times per month (weekly). Duration of use, in months, was 15.9 +/- 22.1 months (range = 12-36 months). Other Drug Use - 12/12 reported use of alcohol and cannabis, 3/12 reported (short-term) use of heroin, and 2/12 reported episodic use of cocaine. Group Demographics and Matched Variables - Authors matched ecstasy users and controls on gender (all male) and age; groups were reportedly matched for education and socioeconomic background. Gender, as MF variable, ecstasy users = 12/0, non-users = 20/0. Age - Average age of ecstasy users was 24 +/- 3.55 years (range = 18-29), and average age of non-users was 26.4 +/- 6.5 years (range = 19-32). Education - No information provided; 3/12 ecstasy users were students. Socioeconomic status - No information given; both ecstasy users and non-users reported to be in middle to upper-middle socioeconomic bracket.

Measures: Aggression - Italian version of BDHI (QTA) measured trait aggression (direct and indirect, verbal, irritability, negativity, resentment, suspiciousness, guilt, and total score). Computerized "game" with fictitious subject measured aggressiveness in response to provocation (Point Subtraction Aggression Paradigm , or PSAP). Participants earned money via pressing one button, and "opponent" could subtract money. Participant could subtract money from opponent (would not go to own account) by pressing different button, and participant could protect money from subtraction by pressing a third button. Aggression measured in 3 FSAP sessions lasting 25 min at hourly intervals, with 30 min break between intervals. Questionnaires completed at end of sessions indicated that participants believed "opponent" to be real.

Physiological Measures - HR, SBP and DBP measured once before each session, and once after completing each session, with measures occurring before and after all 3 FSAP sessions.

Neuroendocrine Measures - ACTH and cortisol measured from blood samples drawn from indwelling catheter, with blood drawn before first FSAP session and immediately after each session (0, 30, 90, 150 min after start of study). Cortisol was assayed by competitive enzyme immunoassay, and ACTH by commercially prepared immunoassay.

Norepinephrine and epinephrine - Epinephrine (E) and norepinephrine (NE) measured in blood drawn before initial FSAP session and immediately after each session (0, 30, 90 and 150 min after study). Both E and NE were assayed via HPLC with electrochemical detection.

Analyses: Laboratory aggression measure (FSAP) - Earning, aggression (subtract money) and escape responses examined with a 2 x 3 mixed between subjects/repeated measures ANOVA, with drug use (ecstasy user versus non-user) as the between subjects factor and session (Session 1, 2 or 3) as repeated measures. Unspecified post-hoc tests were used to compare significant differences, and p. = 0.05.

Trait Aggression - QTA (Italian BDHI) scores compared across groups via student's t test.

Neuroendocrine measures and E and NE - AUCs were calculated for cortisol, ACTH, E and NE. A mixed 2 x 3 between-subjects / repeated measures ANOVA was performed for each value (cortisol, ACTH, E, NE), with time of sample (0, 30, 90 and 150 min) serving as the repeated measure and drug use (ecstasy user versus non-user) serving as a between-subjects variable. Differences in AUCs (apparently basal versus after sessions) considered a measure of individual neuroendocrine pattern associated with aggressive responding.

Associations between aggressive response and neuroendocrine values - Possible relationships between cortisol, ACTH, E and NE and aggressive response were assessed via Pearson's r.

Results - Significant Differences Found: Trait Aggression - Ecstasy users scored higher than non-users on QTA direct aggression and irritability scores.

Laboratory Aggression Assessment (FSAP) - Pressing subtraction button (aggressive response) was positively correlated with direct aggressiveness and irritability scales of QTA. Ecstasy users made significantly more "subtractions" (aggressive response) across all three sessions, when compared to non-users. (While authors do not comment on it, figure indicates that aggressive responses appear to decline over sessions, so that the fewest aggressive responses are made in the final sessions compared with the first session). Ecstasy users were significantly more likely to press "protection" (escape) button during first FSAP session, but not the second or third session.

Physiological Measures - HR and SBP (but not DBP) increased for both ecstasy users and non-users over FSAP sessions. HR and SBP after FSAP sessions were significantly higher in ecstasy users when compared to non-users. Aggressive response was associated with increased HR and SBP, but not DBP, for both ecstasy users and non-users.

Neuroendocrine Measures - Basal levels (before FSAP) of cortisol and ACTH were higher in ecstasy users than in controls. ACTH was higher in both ecstasy users and non-users after FSAP Session 1. Plasma ACTH was higher for ecstasy users across all 3 FSAP sessions. Cortisol rose significantly from baseline in both groups after FSAP sessions; however, while cortisol was elevated for all 3 sessions for non-users, it was only significantly higher for ecstasy users after the first FSAP session.

Norepinephrine and Epinephrine - Both ecstasy users and non-users had higher plasma NE levels after Session 3, when compared with basal levels. Ecstasy users had higher NE levels after all 3 FSAP sessions. Both ecstasy users and non-users had higher plasma E levels after FSAP Sessions 2 and 3, as compared with basal levels. Ecstasy users had significantly higher plasma E after all FSAP sessions.

Relationships Between Aggressive Response and Neuroendocrine Values and Neurotransmitter Values - There was a positive association between levels of cortisol, NE and E with aggressive responding for both ecstasy users and non-users (more aggressive responses = higher values for all three). Relationship between Aggressive Responses and Extent of Ecstasy Use - There was a positive association between number of aggressive responses and number of ecstasy tablets taken over a lifetime

Results - No Significant Differences: Trait Aggression - Ecstasy users and non-users did not have significantly different scores on all other QTA scales (indirect aggression, verbal, negativity, resentment, suspiciousness, guilt).

Laboratory Aggression Assessment (FSAP) - There were no significant differences in monetary earnings or in maintaining responses for earnings in ecstasy users and non-users; ecstasy users earned slightly, but not significantly, less than non-users. Ecstasy users were slightly more likely to use "protection" (escape) button, but this was not significant.

Physiological measures - FSAP sessions did not increase DBP. Ecstasy users did not have higher DBP after FSAP sessions than did non-users. DBP was not associated with aggressive response in either group of volunteers.

Norepinephrine and epinephrine - Ecstasy users and non-users did not have significantly different basal levels of NE or E.

Relationships Between Aggressive Response and Neuroendocrine Values and Neurotransmitter Values - There was no association between levels of ACTH and aggressive responses in ecstasy users or in non-users. Ecstasy users and non-users did not differ in the degree of association between aggressive response and levels of cortisol, NE and E.

Relationship between Aggressive Responses and Extent of Ecstasy Use - There was apparently no significant association between duration of ecstasy use and number of aggressive responses made during the FSAP sessions.

Overall Effects: When tested in an experimental paradigm intended to elicit defensive aggression through provocation by a fictitious "opponent," men who had taken ecstasy at least 50 times were more likely to respond aggressively than men who had never taken ecstasy. Both groups earned similar amounts of money (via pressing a button on an FR schedule) and both maintained button pressing for money. There were also no overall differences between ecstasy users and non-users in the use of the "escape" button, which allowed participants to protect their earnings from further subtractions, though ecstasy users used the "escape" function more than non-users in the first FSAP session. Both ecstasy users and non-users were reactive to the FSAP situation, with both experiencing elevated HR and SBP, but ecstasy users appeared to be more reactive to the conditions of the FSAP, with higher HR and SBP during these sessions. Ecstasy users also had higher basal levels of cortisol, and increased ACTH throughout all 3 FSAP sessions. On the other hand, while cortisol was elevated in both groups after FSAP sessions when compared to baseline, cortisol was significantly elevated in ecstasy users only after FSAP session 1, whereas it remained elevated in non-users for all 3 sessions. Ecstasy users had higher levels of NE and E after all FSAP sessions, whereas levels of these neurotransmitters were increased in non-users only after FSAP Sessions 2 and 3. Aggressive responses were associated with increase in neurohormones and in norepinephrine and epinephrine, and with increased cardiovascular response, and number of aggressive responses was positively correlated with number of ecstasy tablets taken in a lifetime. The authors' hypothesis was confirmed, in that extent of aggressive responses evinced in the laboratory by the FSAP paradigm were associated with overall lifetime use (duration of use was apparently not associated with increased aggressive response).

Comments: This is the first paper to employ a behavioral assessment of aggressiveness in a comparison between ecstasy users and non-users. One straightforward interpretation of this paper is that individuals with higher self-reported aggressiveness will behave with higher aggressiveness than those with lower self-reported aggressiveness. This is an interesting result, but not as interesting as it would have been if a behavioral difference had been shown in volunteer groups that were matched for personality and risk taking/illicit drug use behaviors(other than ecstasy use). The dissociation between release of stress hormones and release of norepinephrine and epinephrine is interesting and probably deserves further exploration, both inside and outside the study of long-term effects of ecstasy use. Earlier findings by the same authors (Gerra et al. 2000) reported finding that ecstasy users ceased to have higher scores QTA aggressiveness scores than non-user controls after 12 months' abstinence from ecstasy. The findings reported suffer from the same limitations faced by earlier studies conducted by the same team (Gerra et al, 2000; Gerra et al. 1998). In all cases, ecstasy users were drawn from a sample of individuals who sought information or treatment about drug-related problems (though it is true that not all ecstasy users in this study are inpatients). All participants are male, and insufficient information is presented for evaluating how well matched participants are in education and use of drugs other than ecstasy. Non-users were recruited from hospital employees and may have been reluctant to admit to fellow employees their use of illegal drugs. Several studies (some of them cited by the authors of the current paper) indicate illicit drug users are generally more likely to engage in aggressive behavior than non-users, regardless of the specific drugs used. Although users and non-users were reported to be matched on social economic background, all non-users were employed while four of 12 users were unemployed and 3 of 12 users were students. Thus, users may have had a different financial incentive from non-users, although it should be noted that there was no evidence of such difference in behavioral measures. The study also shares the limitations of other retrospective studies. In its favor, this paper maintains the use of frequent urinary testing for presence of recent drug use rather than relying on self-report alone to assess compliance with requirement for abstinence from ecstasy prior to the study day. Accordingly, the presence of MDMA was confirmed in user biofluids three weeks before behavioral testing. It will be interesting to see whether the reported aggressive behavior decreases with abstinence from MDMA, as self-reported aggression has previously been reported by the authors to decrease. Of perhaps greater interest would be a study exploring likelihood of cooperative or other-rewarding responses between ecstasy users and non-users.