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Trial registered on ANZCTR

Registration number

ACTRN12624000645550p

Ethics application status

Submitted, not yet approved

Date submitted

16/04/2024

Date registered

20/05/2024

Date last updated

20/05/2024

Date data sharing statement initially provided

20/05/2024

Type of registration

Prospectively registered

Titles & IDs

Public title

Recollection of Event Memory following Drugs, Alcohol, and Stress

Scientific title

Recollection of Event Memory following Drugs, Alcohol, and Stress in Adults Who Have Used Substances Previously

Secondary ID [1]

nil

Universal Trial Number (UTN)

Trial acronym

REMDAS

Linked study record

Health condition

Health condition(s) or problem(s) studied:

memory impairment

Condition category

Condition code

Mental Health

Studies of normal psychology, cognitive function and behaviour

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

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).

Intervention code [1]

Treatment: Other

Comparator / control treatment

Positive control: Alcohol; vodka mixed with 100mL tonic water to reach average blood alcohol concentration (BAC) 0.08%; The alcohol placebo will be 100mL tonic water with the rim of the glass rubbed with alcohol, etc.

Negative control: placebo tablets designed to look the same as the dexamphetamine tablets. Placebo formulation includes: Microcrystalline Cellulose, Colloidal Silicon Dioxide, Sodium Starch Glycolate, Sodium Stearyl Fumarate.

Consumption is monitored by the research nurse to ensure adherence.

Control group

Placebo

Outcomes

Primary outcome [1]

Recall memory under stress

Timepoint [1]

Approx 45 mins post substance ingestion

Primary outcome [2]

Recall and recognition memory

Timepoint [2]

Approx 45 mins post substance ingestion

Primary outcome [3]

Face recognition memory (visual)

Timepoint [3]

Approx 45 mins post substance ingestion

Secondary outcome [1]

Salivary cortisol

Timepoint [1]

Repeated measures design over 3 time points; within session cortisol will be assessed via saliva at 3 time points: baseline, 35 mins post stressor, and 50 mins post stressor

Secondary outcome [2]

Stress ratings

Timepoint [2]

Assessed 6 times across session; 1 baseline, 1 approx 45 mins post MAST, 15 mins later, 15 mins later again, approx 3 hours later, and at discharge

Secondary outcome [3]

Positive and Negative Affect Schedule (PANAS)

Timepoint [3]

collected at baseline and approx 45 mins post stressor (MAST)

Secondary outcome [4]

Amphetamine intoxication

Timepoint [4]

6 time points: 45 mins post drug administration, 15 mins after that, 15 mins after that, then at approx 4pm (4 hours post drug administration), 30 mins after that, and at discharge (approx 5pm)

Secondary outcome [5]

Alcohol intoxication

Timepoint [5]

6 timepoints across study session: approx 45 mins post substance administration, 15 mins after that, 15 mins after that, 4pm, 4.30, 5pm (discharge)

Secondary outcome [6]

Stress and pain responses to MAST: composite

Timepoint [6]

Approx 45 mins post stressor

Secondary outcome [7]

Stress via salivary alpha amylase

Timepoint [7]

Approx 2 mins post stressor

Eligibility

Key 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.

Minimum age

18 Years

Maximum age

65 Years

Sex

Both males and females

Can healthy volunteers participate?

Key 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.

Study design

Purpose of the study

Educational / counselling / training

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Central randomisation by computer

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Permuted block randomisation

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data

Intervention assignment

Crossover

Other design features

Phase

Not Applicable

Type of endpoint/s

Pharmacokinetics / pharmacodynamics

Statistical methods / analysis

Data analysis will primarily be conducted using SPSS and R. We plan to employ mixed repeated measures ANOVAs to assess main effects (alcohol vs amphetamine vs placebo) and interaction terms related to substance administration, memory performance, and response to stress status. This approach allows for a comprehensive examination of the effects of these factors on our variables of interest.

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

17/06/2024

Actual

Date of last participant enrolment

Anticipated

17/06/2025

Actual

Date of last data collection

Anticipated

10/07/2025

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

NSW

Recruitment hospital [1]

Royal North Shore Hospital - St Leonards

Recruitment postcode(s) [1]

2065 - St Leonards

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

Australian Research Council (ARC)

Address [1]

Country [1]

Australia

Funding source category [2]

Other

Name [2]

Ramsay Health Care

Address [2]

Country [2]

Australia

Primary sponsor type

University

Name

University of Sydney

Address

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Submitted, not yet approved

Ethics committee name [1]

Northern Sydney Local Health District Human Research Ethics Committee

Ethics committee address [1]

https://www.nslhd.health.nsw.gov.au/Research/ResearchOffice/Pages/HREC.aspx

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

14/07/2023

Approval date [1]

Ethics approval number [1]

Summary

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).

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr Lauren Monds

Address

Central Clinical School, Faculty of Medicine and Health, USYD; 92 Parramatta Rd, Camperdown, NSW, 2050

Country

Australia

Phone

+61 2 9036 3136

Fax

[email protected]

Contact person for public queries

Name

Lauren Monds

Address

Central Clinical School, Faculty of Medicine and Health, USYD; 92 Parramatta Rd, Camperdown, NSW, 2050

Country

Australia

Phone

+61 2 9036 3136

Fax

[email protected]

Contact person for scientific queries

Name

Lauren Monds

Address

Central Clinical School, Faculty of Medicine and Health, USYD; 92 Parramatta Rd, Camperdown, NSW, 2050

Country

Australia

Phone

+61 2 9036 3136

Fax

[email protected]

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

What supporting documents are/will be available?

Doc. No.	Type	Citation	Link	Email	Other Details	Attachment
22209	Study protocol		https://osf.io/r2unh
22211	Statistical analysis plan		https://osf.io/r2unh

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

No additional documents have been identified.

Trial Review

Documents added manually

Documents added automatically