None listed
Conditions
Brief summary
Understanding the effect of intoxication on witnesses is important to the legal system, but there are key gaps in our knowledge in this area. While the research on alcohol and memory is advancing (e.g., see Jores et al., 2019), there is still little known on other substance effects in an eyewitness context. Specifically, there is minimal research on amphetamines and event memory, and no known research on any type of amphetamines and their impact on face recognition in a line-up context. This leaves many remaining questions and gaps which this study aims to fill as itpertains to dosage, timing, expectancy effects (i.e., anticipating potential substance effects that influence performance). Furthermore, many crimes are distressing in nature, however minimal research has explored intoxication and memory in the context of a distressing event. The role of stress must also be addressed because stress hormones are released during amphetamine use. This requires research about whether stress and amphetamine intoxication combine to impact memory. Additionally, it is unclear whether alcohol use will reduce the stress response, or whether stress will lead to a pause in alcohol metabolism, and how either of these may interact with memory. Study hypotheses: it is anticipated that alcohol may impair memory completeness but not accuracy, whereas it is possible that dexamfetamine may improve memory. An exploratory aim is to investigate whether stress impacts drug response (e.g., makes drug effects more or less pronounced and subsequently impacts memory accordingly).
Interventions
This trial uses a crossover study design where each participant will attend 3 sessions with a washout period of 1 week in between each session. Comparison will be made between alcohol (positive control) and placebo (negative control) with the substance of interest dexamfetamine (2omg oral tablet) across three experimental sessions. Participants will attend these sessions in a randomly assigned order, for example:
Visit 1: Amphetamine pills + Placebo alcohol
Visit 2: Placebo pills + Alcohol
Visi
This trial uses a crossover study design where each participant will attend 3 sessions with a washout period of 1 week in between each session. Comparison will be made between alcohol (positive control) and placebo (negative control) with the substance of interest dexamfetamine (2omg oral tablet) across three experimental sessions. Participants will attend these sessions in a randomly assigned order, for example: Visit 1: Amphetamine pills + Placebo alcohol Visit 2: Placebo pills + Alcohol Visit 3: Placebo pills + Placebo alcohol The study also uses double dummy blinding, where participants will consume two substances (drinks and pills) in each session but will not know which is placebo and which is active, and in one session both substances will be placebo. There is no condition where both alcohol and amphetamine will be consumed in the same session. Participants will be instructed to abstain from alcohol and drugs for 24 hours, and from cigarettes, caffeine or eating for two hours before the sessions. At the beginning of each session, participants will be cannulated (for the blood tests), complete the demographics and drug history questionnaire, and receive a baseline blood and saliva test. Dexamfetamine/placebo pills will be administered by the study research nurse. Bloods will be taken across 4 time points each session to quantify plasma levels of substance. The stress and memory tests will occur at each study visit. The stress test is the Maastricht Acute Stress Test which involves arm submersion in ice water, alongside a social threat (maths task while evaluated and filmed). Memory will be tested via recall of the MAST event (to-be-remembered items to be counterbalanced across session), the DRM word list task, and a face recognition task (employing the Chicago Face database). Memory and stress tests will occur approximately 30 minutes post substance administration. Salivary cortisol will be collected to quantify stress levels. These tasks will be completed by trained researchers. Participants will remain on site until it is safe for them to leave as per standard clinical protocols (e.g., > 4 hours since dose, clinician review).
Sponsors
University of Sydney
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Educational / counselling / training
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
1) Self-reported previous experience with the substance of interest but not current regular use. Regular use is defined as taking amphetamines for non-medical purposes more than once a week. 2) Adequate cognition and English to consent and complete the study. This will be determined by the researcher who administers the phone screening.
Exclusion criteria
1) Current, clinically significant physical disease (e.g., cardiac, liver). The nurse or doctor associated with the study will make this determination based on an examination of the potential participant. 2) Severe psychiatric illness (i.e., schizophrenia, suicide risk). The nurse or doctor associated with the study will make this determination based on an examination of the potential participant. 3) Current substance use disorder other than nicotine. The nurse or doctor associated with the study will make this determination based on an examination of the potential participant and the diagnostic tools. 4) Previous hypersensitivity/adverse reaction to the studied drugs. We will evaluate this based on the potential participant’s self-report. 5) Current medication use that is a contraindication for the study drug or interferes with drug absorption. The nurse or doctor associated with the study will make this determination based on an examination of the potential participant. Stable antidepressant use for > one month will be permitted. 6) Oral-contraceptive use in females. We will evaluate this based on the potential participant’s self-report. 7) Current pregnancy/lactation. We will evaluate this based on the potential participant’s self-report in the first instance (phone screen) but also via pregnancy testing prior to study session commencement. 8) Women of child-bearing capacity who are not prepared to use (non-pharmacological) contraception during the study. We will evaluate this based on the potential participant’s self-report.
Outcome results
None listed