Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12615000619549
Ethics application status
Approved
Date submitted
21/05/2015
Date registered
15/06/2015
Date last updated
9/01/2019
Date data sharing statement initially provided
9/01/2019
Date results information initially provided
9/01/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
Dexamphetamine effects on the perceptions of visual, auditory, tactile and multimodal illusions in healthy volunteers
Scientific title
Dexamphetamine effects on healthy volunteers in a cross-over design on the perceptions of visually, auditory, tactile and multimodal illusions
Secondary ID [1] 286771 0
Nil
Universal Trial Number (UTN)
Nil
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
This is a dexamphetamine challenge study in healthy volunteers as a model for studying dopaminergic mechanisms in psychoses 295147 0
Condition category
Condition code
Mental Health 295387 295387 0 0
Schizophrenia

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
dexamphetamine (0.45 mg/kg, by mouth with gelatine capsules) once only, and placebo: gelatine capsules filled with glucose. The two treatments are given about a week apart (minimum 5 days). Dexamphetamine levels determined from five saliva samples taken throughout the day, at about 70 min intervals.
Intervention code [1] 291927 0
Treatment: Drugs
Comparator / control treatment
Placebo (gelatine capsules identical to those used for dexamphetamine but filled with similar weights of glucose)
Control group
Placebo

Outcomes
Primary outcome [1] 295127 0
Visual Flash illusions. The experience of illusions related to the number of light flashes observed in the presence of additional light flashes or brief sounds will be measured by recording the number of flashes that the participant says that they see, along with a record from the participant pressing a number key on a computer keyboard or joystick representing the number of flashes observed.
Timepoint [1] 295127 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 15 minutes 60 minutes after consuming the capsules and again for 25 minutes 125 minutes after consuming the capsules.
Primary outcome [2] 295216 0
Phantom Word Illusion. Participants' experience of hear words will be measured while listening to sounds through stereo headphones and repeating any words heard. The number of different words heard and the time from the beginning of the sounds to when the words are heard will be measured by recording the words spoken by the participants, as well as by measuring joystick presses each time a different word is heard.
Timepoint [2] 295216 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 10 minutes 80 minutes after consuming the capsules.
Primary outcome [3] 295217 0
Tactile funnelling illusion. This illusion is produced by touching a person's arm at points with callipers, while the arm is obscured from vision with a barrier. It is measured by recording the number points felt, and by the participant pointing to where they felt the touch with their hand.
Timepoint [3] 295217 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 15 minutes 225 minutes.
Secondary outcome [1] 314820 0
This is a primary outcome:
Marble hand illusion. This illusion is produced by tapping the hand gently with an automated tapper, while listening to the sound of the hand being tapped through a headset. Gradually, the sound of the tapping is changed, and with it so does the feeling of the hand. The feeling of the hand is assessed with the Senna et al. (2014) questionnaire (Senna I, Maravita A, Bolognini N and Parise CV (2014) The marble-hand illusion. PLoS One 9:e91688.)
Timepoint [1] 314820 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 30 minutes 240 minutes after consuming the capsules.
Secondary outcome [2] 315091 0
This is a primary outcome.
McGurk effect. This illusion is produced by watching a video of a person's face while that person makes the sound of a syllable. At the same time, the participant listens to syllables uttered by that person through stereo headphones. What syllables are heard and when are measured by recording the participants' saying out loud what syllables they hear.
Timepoint [2] 315091 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 15 minutes 60 minutes after consuming the capsules and again for 25 minutes 275 minutes after consuming the capsules.
Secondary outcome [3] 315092 0
Dexamphetamine saliva levels. About 1-2 ml of saliva are collected 5 times each of the two days, and are used to measure dexamphetamine levels, measured by high performance liquid chromatography with ultraviolet detection.
Timepoint [3] 315092 0
These samples are collected on both test days just before consuming the capsules and at about 70 min intervals thereafter, until 5 samples are taken.
Secondary outcome [4] 315093 0
blood-pressure. This is measured using an automated blood-pressure device
Timepoint [4] 315093 0
Blood pressure is measured in triplicate on both test days just before consuming the capsules and at about 70 min intervals thereafter, until 5 triplicates are measured.
Secondary outcome [5] 315094 0
Heart rate is measured using an automated blood-pressure device.
Timepoint [5] 315094 0
Heart rate is measured in triplicate on both test days just before consuming the capsules and at about 70 min intervals thereafter, until 5 triplicates are measured.
Secondary outcome [6] 315097 0
Brief Psychiatric Rating Scale. This is measured by one of the experimenters asking questions of the participants.
Timepoint [6] 315097 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 8 minutes 95 minutes after consuming the capsules
Secondary outcome [7] 315098 0
Magical Ideation Scale. This is measured by the participants' filling out a brief yes/no questionnaire.
Timepoint [7] 315098 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 5 minutes 90 minutes after consuming the capsules
Secondary outcome [8] 315099 0
Scale for the Assessment of Positive Symptoms. This is measured by the participants filling out a brief questionnaire, and by an experimenter also filling out a brief questionnaire.
Timepoint [8] 315099 0
This will be measured on both days of testing (placebo and dexamphetamine days) for about 5 minutes 103 minutes after consuming the capsules
Secondary outcome [9] 315100 0
Amphetamine scale. This is measured by the participants' filling out a very brief visual analog scale about how they are feeling at that moment in time.
Timepoint [9] 315100 0
Amphetamine-like feelings are measured on both test days just before consuming the capsules and at about 70 min intervals thereafter, until measured 5 times.

Eligibility
Key inclusion criteria
Healthy people >17 and <60 years of age
Minimum age
18 Years
Maximum age
59 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
1. Heart or severe blood vessel disease,
2. High blood pressure (> 180/90 mm Hg),
3. Glaucoma,
4. Hyperthyroidism (overactive thyroid),
5. Tics (muscle twitching usually in the face or shoulders),
6. Sensitivity to dexamphetamine or sympathomimetic amines,
7. Any degenerative disease of the nervous system,
8. Epilepsy, or other neurological disorder, including head injury.
9. Tourette's syndrome or a family history of this disorder,
10. A psychiatric or psychological problem for which they are receiving treatment (schizophrenia, depression, anxiety, etc),
11. A serious medical problem for which they are receiving treatment (cardiovascular disorders, respiratory disorders, etc),
12. Had or are currently receiving treatment for substance abuse,
13. A family history of schizophrenia in first-degree relatives (parents, children or siblings),
14. Previously experienced hypersensitivity to dexamphet-amine,
15. Used any drug including alcohol or any illicit drug within 24 hours of each testing session,
16. Used caffeine on the day of each testing session,
17. Current prescription medication that you are taking other than contraceptives or acne medication
18. Used over-the-counter medication in the 48 hours before each testing session

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
This is within-subject cross-over treatment (AB) where the order of treatment is pseudo-randomised within a blocked (counter-balanced) design
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation of treatment from a list of possible orders without replacement for each successive block of 24 participants with 12 having placebo first and the rest with dexamphetamine with the restriction that there are no more than 4 sequential participants with the same order.
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
Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Repeated Analysis of Covariance with drug as a within-subject factor, sex of the participants and drug-order as between-subject factors, and with age as a covariate. Regression analysis with saliva dexamphetamine levels as the predictor.
We used G*Power 3.1 power calculator, and based our predicted mean difference (Drug-Placebo) and standard deviation of the difference on findings in our lab on the effect of dexamphetamine on the "embodiment" component of the questionnaire assessing changes in the perception of embodiment of the rubber hand, with an effect size of 0.43 (observed under the synchronous condition of the tactile stimulus type condition) with alpha=0.5, with a power of 0.80 (80%), with a two-tailed test and assuming the presence of a sex difference.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
15/06/2015
Actual
27/07/2015
Date of last participant enrolment
Anticipated
25/10/2019
Actual
21/09/2017
Date of last data collection
Anticipated
Actual
28/09/2017
Sample size
Target
72
Accrual to date
Final
66
Recruitment in Australia
Recruitment state(s)
WA

Funding & Sponsors
Funding source category [1] 291318 0
University
Name [1] 291318 0
University of Western Australia
Country [1] 291318 0
Australia
Primary sponsor type
Individual
Name
Mathew Martin-Iverson
Address
Pharmacology M510,
University of Western Australia
35 Stirling Highway,
Crawley WA 6009
Australia
Country
Australia
Secondary sponsor category [1] 289998 0
Individual
Name [1] 289998 0
Dr Joseph Lee
Address [1] 289998 0
School of Psychiatry and Clinical Neuroscience,
University of Western Australia
35 Stirling Highway,
Crawley WA 6009
Australia
Country [1] 289998 0
Australia
Secondary sponsor category [2] 289999 0
Individual
Name [2] 289999 0
Dr Rajan Iyyalol
Address [2] 289999 0
Graylands Hospital
Brockway Rd, Mount Claremont WA 6010
Country [2] 289999 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 292883 0
University of Western Australia Human Research Ethics Committee
Ethics committee address [1] 292883 0
University of Western Australia
35 Stirling Highway,
Crawley WA 6009
Australia
Ethics committee country [1] 292883 0
Australia
Date submitted for ethics approval [1] 292883 0
20/05/2015
Approval date [1] 292883 0
16/07/2015
Ethics approval number [1] 292883 0
RA4/1/7557

Summary
Brief summary
Our previous research demonstrated similarities between dexamphetamine effects in healthy volunteers in illusions involving visual and tactile stimuli and the experience of the same illusions in people with schizophrenia experiencing passivity symptoms. Passivity symptoms are the feeling of being controlled by an external force and not being the agent of one's own actions, thoughts or feelings, one of the first rank symptoms that also includes hearing voices talking "in one's head", the belief that thoughts are being inserted into or withdrawn from one’s conscious mind, or the belief that one’s thoughts are being broadcast to other people). To further elucidate the role of dopamine in these phenomena, we will determine if the effects of dexamphetamine are based on specific actions on the visual sensory system, the tactile sensory system, or the higher level integration of both. In addition, we will determine if the effects are specific to the integration of these two sensory systems, or if they generalise to other sensory systems, especially the auditory system, which prior research indicates is more affected than the visual system by both dexamphetamine and in schizophrenia. Prior research from our lab indicates that that there is a dopamine-dependent widening of the window of the time in which stimuli become associated, either in a way to bind them as a single perceptual experience, or in a way that is perceived as a causal relationship, that may provide a common mechanism to explain many of the symptoms and signs of schizophrenia, especially the first-rank symptoms including passivity symptoms. The broad purpose of this study is the elucidation of the role of the dopamine in abnormal perceptual experiences, by manipulating dopamine levels with dexamphetamine and measuring the consequence on the experience of illusions, especially under conditions in which we assess the temporal window of associability, as compared with other similar research in people with schizophrenia.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 57486 0
Prof Mathew Martin-Iverson
Address 57486 0
University of Western Australia
Pharmacology, M510,
35 Stirling Highway,
Crawley WA 6009
Australia
Country 57486 0
Australia
Phone 57486 0
+61 8 64572982
Fax 57486 0
+61 8 64573479
Email 57486 0
[email protected]
Contact person for public queries
Name 57487 0
Prof Mathew Martin-Iverson
Address 57487 0
University of Western Australia
Pharmacology, M510,
35 Stirling Highway,
Crawley WA 6009
Australia
Country 57487 0
Australia
Phone 57487 0
+61 8 6457 2982
Fax 57487 0
+61 8 6457 3479
Email 57487 0
[email protected]
Contact person for scientific queries
Name 57488 0
Prof Mathew Martin-Iverson
Address 57488 0
University of Western Australia
Pharmacology, M510,
35 Stirling Highway,
Crawley WA 6009
Australia
Country 57488 0
Australia
Phone 57488 0
+61 8 9347-6443
Fax 57488 0
+61 (8) 9346-3469
Email 57488 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Confidentiality of data required by HREC


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
SourceTitleYear of PublicationDOI
EmbaseDexamphetamine widens temporal and spatial binding windows in healthy participants.2023https://dx.doi.org/10.1503/jpn.220149
N.B. These documents automatically identified may not have been verified by the study sponsor.