None listed
Conditions
Brief summary
The primary aim of this research is to investigate how acute exercise affects executive function and whether these effects are modulated by transcranial Direct Current Stimulation (tDCS) of the dorsolateral prefrontal cortex. While we are not directly measuring dopamine levels, we hypothesize that exercise may induce changes in dopamine, which in turn could influence the outcomes of tDCS on executive function. The study will explore the impact of different exercise intensities, ranging from very light to moderate, on these effects.
Interventions
Trial Stages:
1. Initial Assessment (Pre-transcranial direct current stimulation [tDCS]): Participants complete three computerized tasks designed to measure aspects of executive function — cognitive flexibility, response inhibition, and reversal learning. This baseline measurement occurs before any intervention to establish participants' cognitive performance levels prior to the application of acute exercise and tDCS. It is estimated that it will take participants between 8-10 minutes to complet
Trial Stages: 1. Initial Assessment (Pre-transcranial direct current stimulation [tDCS]): Participants complete three computerized tasks designed to measure aspects of executive function — cognitive flexibility, response inhibition, and reversal learning. This baseline measurement occurs before any intervention to establish participants' cognitive performance levels prior to the application of acute exercise and tDCS. It is estimated that it will take participants between 8-10 minutes to complete these tasks. 2. Pre-Treatment Randomisation: Following the initial assessment, participants are randomly assigned to engage in one of three conditions on a stationary bike: rest, very light activity (50%-60% of maximal heart rate [mhr], where mhr is calculated by the formula [220-age]), or moderate activity (70%-80% of maximal heart rate) for 20 minutes. To ensure adherence to the exercise protocol, heart rate monitors will be used. Participants complete this stage of testing one-on-one. 3. tDCS Administration: After the exercise, participants receive a total of 20 minutes of tDCS (either active or sham; this is part of a randomized, counterbalanced, and repeated measures component) targeted at the left dorsolateral prefrontal cortex (anode on F3 and cathode on Fp2). For the first 10 minutes of tDCS, participants do not engage in any activity. This 10-minute period is necessary for the tDCS to exert its neurophysiological and cognitive effects. 4. Treatment Phase (During tDCS): Starting from minute 10, participants perform the same executive function tasks they completed during the initial assessment, while tDCS is still being applied. The tDCS is discontinued once the executive function tasks are completed or after 20 minutes. This stage is critical for assessing the immediate impact of tDCS (modulated by preceding exercise) on executive function. In the second testing session, (separated by a minimum of 72 hours to prevent carryover effects of tDCS) participants will receive the alternate tDCS condition (active if they received sham in session 1, and vice versa) and will complete the same exercise conditions and executive function tasks as in the first session. 5. Trial Exit: After completing both testing sessions, each participant concludes their involvement in the study. All testing will be supervised by the Principal Investigator and carried out by three honours research students at the Mind & Body Lab, Murdoch University, ensuring close monitoring for protocol adherence.
Sponsors
Murdoch University
Study design
Allocation
Randomised controlled trial
Intervention model
Other
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver)
Eligibility
Sex/Gender
All
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
• Are aged between 18 and 50 years. The upper age limit of 50 years has been chosen based on evidence suggesting the onset of very mild cognitive decline may begin past this age. • Engage in regular cardiovascular activities (e.g., at least twice a week). • Agree to fast for 3 hours prior to testing (only water or herbal tea is allowed). This is because glucose levels are known to modulate performance in several cognitive domains. By having all participants fast for 3 hours prior to testing, we aim to control for any potential enhancing effects of glucose on executive function.
Exclusion criteria
Participants will not be able to participate if they: • Suffer from cardiac, hepatic, renal, and/or neurological disorders. • Have damaged or diseased skin on your face and scalp or have a sensitive scalp. • Have a history of alcohol or drug addiction, or severe psychiatric illness. • Are receiving drug treatment known to lower the seizure threshold (e.g., treatments for epilepsy). • Are pregnant. • Are sleep deprived, meaning you have slept less than 6 hours the night before testing. • Have metallic dental fillings, orthodontic appliances, a cardiac pacemaker, cochlear implant, and/or surgical clips in your body. • Have a medical history of migraine or frequent headaches.
Outcome results
None listed