Pharmacological Modulation of Belief Salience (MOBS)
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|ClinicalTrials.gov Identifier: NCT03754062|
Recruitment Status : Completed
First Posted : November 27, 2018
Last Update Posted : October 10, 2019
To provide an initial test of the hypothesis that dopamine mediates the motivational salience of stimuli beyond simple stimulus-reinforcement associations, the researchers propose to undertake a study of the modulation of a) levels of agreement or disagreement with; b) the perceived self- relevance; and c) the perceived interest of propositions expressing beliefs and values in healthy male volunteers using Ii) a dopamine antagonist (the D2-blocker haloperidol), and (ii) a dopamine precursor L-Dopa to increase CNS dopamine transmission.
The researchers will also administer the Salience Attribution Task (SAT) which will allow researchers to assess reward-learning processing of simple stimuli using a reaction-time game. This task was utilised by Roiser et al in order to explore whether delusions in medicated patients with schizophrenia were related to impairments in associative learning. The authors hypothesised that associative learning was influenced by D2 receptor blockade. The researchers extend this approach to examine the effect of dopamine modulation on the SAT as a measure of associative learning, a basic neuropsychological process that may be involved in the attribution of salience to beliefs.
Finally, the researchers will ask participants to perform a within-subjects dictator game to understand the influence of dopaminergic manipulation of the live attribution of harm intention to partners. The task has been previously validated online. Participants will play against 3 partners in a random order in each drug condition. Each partner will play the participant for 6 trials. One partner will always be fair, one will always be unfair, and one will be 50% unfair. We aim to understand whether potentiating dopamine has an additive effect on the harm intention attributions toward partners, regardless of the behaviour of the partner.
|Condition or disease||Intervention/treatment||Phase|
|Haloperidol Placebo L-DOPA||Drug: Placebo - Cap Drug: L-dopa Drug: Haloperidol||Phase 1|
Show Detailed Description
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||30 participants|
|Intervention Model:||Crossover Assignment|
|Intervention Model Description:||Placebo x Haloperidol x LDOPA|
|Masking:||Double (Participant, Investigator)|
|Masking Description:||Double blind|
|Primary Purpose:||Basic Science|
|Official Title:||Pharmacological Modulation of Belief Salience|
|Actual Study Start Date :||June 1, 2017|
|Actual Primary Completion Date :||September 1, 2019|
|Actual Study Completion Date :||September 1, 2019|
Placebo Comparator: Placebo
Drug: Placebo - Cap
Administration of Placebo by pill.
Experimental: Haloperidol 3mg
Administration of Haloperidol by pill.
Experimental: L-Dopa 150 mg & Domperidone 10mg
Administration of L-dopa by pill.
- Beliefs and Values Inventory (BVI) [ Time Frame: 12 Months ]Change in score between conditions on the BVI. Scores will be summed by item totals within theme (paranormal, religion, morality, politics, and science) and dimension (agreement, self-relevance, and interest).
- Salience Attribution Test (SAT) [ Time Frame: 12 Months ]Change in attribution of explicit and implicit salience between conditions on the SAT.
- Within-subjects dictator game [ Time Frame: 12 Months ]
Participants will play against three different partners, each for six trials. In each trial, the player's partner will have the option to either split or take 10p from the player, so that the player either ends up with 5p or 0p. Players will play against one partner that will always split the money, one that will always take all of the money, and one that will 50% of the time split the money. After each trial, the player will be asked on a scale of 1-100 (1 being not at all and 100 being completely):
- How much do you think your partner was driven by a desire to increase their own bonus, and
- How much do you think your partner was driven by a desire to reduce your bonus.
Total of a. and b. will be added up for each style of partner for each arm.
- Big-5 Personality Questionnaire [ Time Frame: 6 Months ]
The researchers will calculate the associations between personality dimensions of the Big-5 (extraversion, neuroticism, openness, agreeableness, and conscientiousness) using the 25 item version (scores from 1-5 on a likert scale, with 5 meaning higher agreement with a statement) with variation within-subjects.
Each dimension will be totalled to calculate personality variation.
- Brief Oxford-Liverpool Inventory of Experiences and Feelings [ Time Frame: 6 Months ]
The researchers will calculate the associations between baseline schizotypy scores with variation within-subjects across conditions.
Unusual Experiences (hallucinations etc), Cognitive Disorganisation (cognitive difficulties), Introvertive Anhedonia (loss of pleasure etc.), and Impulsive Nonconformity (impulsiveness) sub-scales will be added up individually (from a scale of 1-5 for each item, 5 being higher agreement with an item) to calculate schizotypy on a number of dimensions.
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03754062
|Centre for Neuroimaging Sciences|
|London, United Kingdom, W1T 7NF|