Materials and Methods.
Design. The study used a double-blind, within-participant design in which healthy adults received MDMA (100mg), MA (20mg) and placebo (PLC) on three separate sessions. At the expected time of peak drug effect participants engaged in an oddball task during which we recorded EEG responses to positive, negative, and neutral faces. ERP components related to different aspects of emotional and cognitive processing were recorded. Participants also completed self-report measures of the drugs’ effects.
Participants. Healthy men and women (N=25) aged 18-35 were recruited from the university and surrounding neighborhoods. Eligibility was determined first by online screening and then by clinical interview and physical examination. Inclusion criteria consisted of a minimum high school education, fluency in English, BMI 18-26, and good health. Exclusion criteria included use of prescription medications, history of cardiac disease or high blood pressure and previous negative experience with MDMA or hallucinogenic substances. Participants had to report between 4 and 40 previous experiences of MDMA to qualify for the study. Women who were not on oral contraceptives were tested only during the follicular phase (1-12 days from menstruation; White, Justice et al. 2002).
Procedure. Participants first attended an orientation to understand the procedures, provide informed consent and practice the tasks from the experimental sessions. They were instructed to abstain from drugs and alcohol for 24 hours before their sessions. They were told they would receive a sedative (e.g., Valium) ,stimulant (e.g., MDMA or amphetamine), or placebo drug in each session. The study was approved by the local institutional review board.
The three, four-hour drug sessions were conducted from 9am-1pm, separated by at least 4 days (M=7.5 days). Upon arrival at the laboratory, participants completed a breathalyzer and urine sample to test for recent drug use (CLIA waived Instant Drug Test Cup, San Diego, CA; amphetamine, cocaine, oxycodone, THC, PCP, MDMA, opiates, benzodiazepines, barbiturates, methadone, methamphetamine, buprenorphine), alcohol use (Alcosensor III, Intoximeters, St. Louis, MO) and pregnancy (in females; Aimstrip, Craig Medical, Vista, CA). They completed pre-capsule questionnaires and cardiovascular measures, measures that were repeated 60, 90, 180 and 240 minutes after the capsule. They ingested capsules containing dextrose (placebo), MA (20mg) or MDMA (100mg) under double blind conditions. Thirty minutes after taking the capsule participants’ EEG electrodes were placed, and recording began about 60 minutes after the capsule. Resting state EEG was determined first, and this was followed by three tasks completed in randomized order. Here we report data on an emotional oddball task assessing responses to happy, angry, and neutral faces (Raz et al., 2014). The EEG measures were obtained from 60 to 150 min post-capsule. After the EEG electrodes were removed, participants rated the arousal and valence of the faces they viewed during the EEG task. Participants left the laboratory after the final measure, 240 min post capsule.
Drugs: MDMA in powdered form (100 mg; Organix Inc, MA) was placed in opaque size 00 capsules with lactose filler. MA tablets (5 mg, total dose 20 mg; Desoxyn, Lundbeck) were placed in an opaque size 00 capsule with dextrose filler, and placebo capsules contained only dextrose.