None listed
Conditions
Brief summary
A) Aims and Objectives This project aims to investigate the role of the neurotransmitter dopamine in complex decision making, and how three prescription stimulant medications that modulate dopamine levels in the brain in slightly different ways can affect the quality of complex decision making. These medications (dextroamphetamine, methylphenidate and modafinil) are increasingly used by healthy people for non-medical, cognitive enhancement purposes, however their effects on basic cognition are often found to be inconsistent, and their effects on more naturalistic, complex optimisation behaviours are not known. B) Key Question(s) Do stimulant medications, that increase dopamine in the brain, enhance, or have a deleterious effect, on the completion of a complex decision making task. More specifically do they; * Affect the amount of time taken to solve a problem? * Increase or decrease the likelihood that a participant will find the correct solution to the problem (the computational performance)? * Increase or decrease the computational distance between the participant’s solution and the correct solution (the economic performance)? * Affect the variety of search paths that participants take through the space of possible solutions? C) Research Design This study will utilize a double-blinded placebo-controlled crossover design. We will recruit 32 healthy participants with no history of neurological, psychiatric or heart conditions. Each one will participate in an initial assessment session and four testing sessions, each at least one week apart to allow for pharmaceutical washout. At each session, the participant will receive either a single dose of the three pharmaceuticals or the placebo. After a 90-minute waiting period, during which the participant fills out number of demographic and personality surveys, the participant will complete a series of computerised complex optimisation tasks and basic cognition tasks. Data collected includes the sequence and timing of the selection of items for each task solution, key variables from the more basic cognitive tasks and the answers to the survey questions.
Interventions
A single oral dose of a capsule containing 15 milligrams dextroamphetamine, 30 milligrams of methylphenidate, 200 milligrams of modafinil or placebo prior to cognitive testing in a repeated-measures full crossover double-blinded design in healthy volunteers. A washout period of at least seven days will be observed between testing sessions. Cognitive testing commences 90 minutes after dosage, and includes solving complex optimisation problems, spatial working memory tests, motor inhibition tests,
A single oral dose of a capsule containing 15 milligrams dextroamphetamine, 30 milligrams of methylphenidate, 200 milligrams of modafinil or placebo prior to cognitive testing in a repeated-measures full crossover double-blinded design in healthy volunteers. A washout period of at least seven days will be observed between testing sessions. Cognitive testing commences 90 minutes after dosage, and includes solving complex optimisation problems, spatial working memory tests, motor inhibition tests, reaction time and spatial problem solving. Cognitive testing will take between 60 and 90 minutes, depending on the speed of the individual participant.
Sponsors
The University of Melbourne
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
Healthy volunteers aged between 18 and 35 years old.
Exclusion criteria
History of psychiatric or neurological illness including epilepsy, head injury, previous use of psychotropic medication, history of significant drug use, heart conditions (including high blood pressure, defined as above 140 mm/Hg systolic and/or 90 mm/Hg diastolic pressure as measured at the initial assessment session) pregnancy, or glaucoma. Any family history of sudden death of a first degree relative through cardiac or unknown causes before the age of 50 years old will also exclude the participant.
Outcome results
None listed