Purpose: Biochemical/metabolic: To examine blood antioxidant levels (including vitamin C and E), antioxidant enzyme activity, and lipoperoxidation (sign of oxidative stress) in Ecstasy users and non-drug using controls.

Design: Retrospective (non-experimental) study design, with drug use (Ecstasy use versus no drug use) serving as a between-group variable, and with all participants undergoing blood sampling for levels of lipoperoxidation, vitamin C, vitamin E, beta-carotene, superoxide dismutase (SOD) and catalase.

Subjects: 120 Ecstasy users and 120 non-user controls apparently residing in or near Hangzhou, China, with no information provided about participant recruitment. Matching - No specific information is provided on group matching. Nevertheless, noting group demographics and authors' statement of using "random control" study suggests that healthy volunteers may have been selected on the basis of demographic characteristics that made them similar to Ecstasy users, with selection made on the basis of demographics, such as age or gender, that would make them similar to Ecstasy users.

Criteria for Inclusion - Ecstasy users - Having used Ecstasy (possibly for at least one month), with Ecstasy use detected via urinary analysis and through self-report. Non-users - Never having used Ecstasy, or other drugs, including sedatives or hypnotics. All groups - Absence of major medical illness (especially those that might relate to differences in blood antioxidant levels), no use of vitamins or beta-carotene supplements, not working in jobs that exposed them to radiation, pesticides or "intoxicating materials," apparently absence of tobacco use or alcohol abuse (undefined). There are no statements concerning length of abstinence from Ecstasy within the study, nor any statement requiring participants to abstain from psychoactives for a given period of time.

Drug Use Parameters - (The authors fail to report a number of standard details of drug use history). No information is provided on lifetime Ecstasy consumption; a rough estimate between 23.2 tablets (assuming high-dose tablets and use twice per month) to 116 tablets (assuming low-dose tablets and use twice per month). Average dose per use, in mg, was 80.75 +/- 19.96 mg (range = 40 to 120). (Text refers to this as "daily use," but it more likely refers to average dose per use than actual dose "per day" every day.) Estimating from milligram dose and MDMA content per tablet, estimated average number of tablets per use is 2-10 tablets, depending on tablet contents. Duration of use, in months, was 5.8 +/- 2.9 months, (range = 1 to 12 months), and no information is provided about frequency of use. No information is provided about time since last use. Tablet MDMA content ranged from 8.75-47.53 mg (authors do not state whether this information was gathered by analysis of tablet contents or by requesting estimates from users). Other drugs - Minimal information is provided about use of other drugs, but the authors state that both Ecstasy users and healthy volunteers did not abuse alcohol (presumably defined differently from use) and did not use tobacco. Given knowledge of drug use behavior outside China, it is difficult to believe that Ecstasy users did not use other substances in addition to Ecstasy.

Group Demographics and Matched Variables - No information is provided concerning sample matching, but it appears that samples were matched on gender, age and tobacco use. Gender, as M/F Ratio - Ecstasy users, 67/53, non-user controls, 60/60. Age - Average, in years, Ecstasy users = 23.5 +/- 3.4 (range = 18-35), non-user controls = 23.6 +/- 3 (range = 20-35). No information is provided about educational attainment in either sample. Other variables - Average body mass index, Ecstasy users = 23.18 +/- 1.26, non-user controls = 23.25 +/- 1.33. Plasma Hemoglobin and albumen - Ecstasy users, hemoglobin = 134.94 +/- 6.96, albumen = 42.62 +/-2.3, non-users hemoglobin = 135.66 +/- 7.19, albumen = 42.85 +/- 2.4 Systolic blood pressure, diastolic blood pressure - Ecstasy users SBP = 110.82 +/- 11.19, DBP = 75.57 +/- 6.73, non-users, SBP = 110.10 +/- 10.52, DBP = 75.29 +/- 6.15

Measures: All antioxidants were assessed from fasting blood samples, apparently only drawn once (time of day unspecified). Erythrocyte lipoperoxide (LPO) was assessed via spectrometry (spectrophotometry) with thiobarbituric acid. Plasma vitamin C was assessed through chemical assay with trichloroacetic acid. Plasma vitamin E was assessed via chemical assay using ethanol and ferric trichloride. Plasma beta-carotene was extracted using ethanol and petroleum ether and assayed with spectrophotometry. Erythrocyte SOD activity was assessed via spectrometry involving inhibiting pyrogallol auto-oxidation. Erythrocyte catalase activity was detected via spectrophotometry using hydrogen peroxide, and acetic acid-potassium dichromate used to determine catalase activity expressed as K/ g Hb.

Analyses: Independent sample t tests were used to examine potential group differences levels of all vitamins, antioxidants and enzyme activities, with levels of each substance or activity in Ecstasy users compared with values in non-user controls. Analyses were performed for plasma levels of LPO, vitamin C, vitamin E, beta-carotene, SOD activity and catalase activity, with p = 0.05 and power = 0.8.

Drug use and plasma antioxidants and erythrocyte enzyme activity - Correlational analyses were performed for each plasma antioxidant or enzyme activity and "MDMA abuse dose" (not clearly defined, but perhaps referring to average dose per use) and duration of use, with p = 0.05.

Results - Significant Differences Found: Ecstasy users had lower plasma vitamin C, vitamin E and beta carotene levels than non-user controls. Ecstasy users had lower erythrocyte SOD and catalase activity than non-users. Ecstasy users had high erythrocyte LPO activity than healthy controls.

Drug use parameters and anti-oxidant levels - There was a negative (inverse) association between "MDMA abuse dose" (possibly average dose per use, though also possibly tablet dosage) and all plasma vitamin levels (vitamin C and E, and beta-carotene), wherein increased MDMA dose was associated with decreased plasma vitamin levels. A negative association was detected between "MDMA abuse dose" and erythrocyte antioxidant enzyme activity (SOD and catalase activity), with increasing dose associated with decreased detectability of enzyme activity. There was a positive association between "MDMA abuse dose" and LPO, with this activity increasing with increasing MDMA dose. Duration of Ecstasy use was negatively (inversely) related to all plasma vitamin levels (vitamin C, vitamin E and beta-carotene), wherein longer duration (in months) was associated with lower vitamin levels. Duration of Ecstasy use was inversely related (negatively associated) with erythrocyte enzyme activity, with longer duration of use associated with lower SOD and catalase activity. There was a positive association between duration of Ecstasy use and LPO activity, with longer duration of use associated with higher levels of LPO.

Results - No Significant Differences: Group differences were found on every vitamin or enzyme activity assessed and reported in this study.

Drug use parameters and antioxidants - All group differences in antioxidant levels and antioxidant enzyme activity were (generally) lower and oxidative stress higher in relation to Ecstasy use variables. However, the authors did not report on frequency of use or time since last use.

Overall Effects: A sample of gender, age, and BMI-matched Ecstasy users had significantly lower levels of antioxidant vitamins than non-user controls, and antioxidant enzyme activity was lower in Ecstasy users. Ecstasy users had greater levels of lipoperoxidation, an index of oxidative stress. Lower levels of vitamins and enzyme activity, and higher lipoperoxidation, were associated with longer duration of Ecstasy use and a variable referred to as "MDMA abuse dose," that may refer to average dose per use or average tablet dosage.

Comments: To date, this is the first report describing evidence of oxidative stress in Ecstasy users. Though the authors attribute higher oxidative stress to hyperthermia or proinflammatory activity, the occurrence of hyperthermia (versus slight increase in body temperature) is rare, and studies in humans and non-human animals (e.g. Pacifici et al. 2002; 2001) suggest that MDMA has anti-inflammatory, and not pro-inflammatory, actions. Though samples were matched for BMI and the authors excluded participants who reported taking nutritional supplements, it is not clear whether intake of specific items (such as sources of vitamin C) were measured or controlled for. Lastly, details of drug use history are poorly reported or reported in a confusing manner, as when the authors seem to indicate that Ecstasy was used "daily," a pattern almost never seen in Europe or North America. It is also surprising that the authors either failed to collect or failed to report on time elapsed from last Ecstasy use to study day, and did not analyze its possible relationship to antioxidant levels, since if MDMA or similar drugs are the cause of oxidative stress, such a relationship would be expected.