None listed
Conditions
Brief summary
Several studies have shown that the efficacy of non-invasive brain stimulation techniques such as tDCS and tRNS on cognitive function is partially modulated by individual characteristics. One of these characteristics is the amount of the neurotransmitter dopamine (DA) that a person has. Because some of the DA that is available in the human body is derived from our diet, one way of estimating DA availability is by using a food questionnaire which can tell us about someone’s tyrosine intake. Tyrosine is an amino acid that can be found in a variety of foods, and that through a chain of metabolizing steps eventually gets converted to DA. Thus, we hope to able to predict the effectiveness of tDCS/tRNS on planning and memory performance by an individual dietary consumption of tyrosine
Interventions
In this study, all participants will first complete a dietary screener questionnaire to capture average weekly tyrosine consumption.
Second, they will then complete two well-established neuropsychological measure of working memory known (Corsi Blocks) and planning (Tower of London). The tests will be administered in the lab using a piece of software called PEBL.
Third, they will undergo three different types of non-invasive brain stimulation: A) active transcranial direct current stimulation (
In this study, all participants will first complete a dietary screener questionnaire to capture average weekly tyrosine consumption. Second, they will then complete two well-established neuropsychological measure of working memory known (Corsi Blocks) and planning (Tower of London). The tests will be administered in the lab using a piece of software called PEBL. Third, they will undergo three different types of non-invasive brain stimulation: A) active transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (dlPFC) with the anode placed on the left and the cathode placed on the right hemisphere; B) active transcranial random noise stimulation (tRNS) with the electrodes placed in the same position as tDCS: C) sham/non-active stimulation. The order of non-invasive brain stimulation allocation will be randomized for each participant. To avoid potential carryover effects of non-invasive brain stimulation, as this is a crossover design, each session will be separated by at least 72 hours. For active tDCS, a current at 1.5 mA will be delivered for 10 minutes while the participant is relaxed plus the additional duration of the participant completing the Corsi Blocks and Tower of London test (approximately 10 minutes) with additional 30-second fade-in/fade-out periods. For active tRNS, a digital high-pass filter is used to damp frequencies below 100 Hz, and deliver frequencies between 100 Hz to 640 Hz, with a maximum possible current set at 1.5 mA. For sham, the stimulation will include only the initial 30-second ramp-up protocol to mimic active non-invasive brain stimulation and ramp down. Masking of the conditions will be achieved using the neuroConn study mode. Testing will be carried out by three honours research students supervised by the PI and carried out in the Mind & Body lab at Murdoch University.
Sponsors
Murdoch University
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
• You are aged between 18 and 50 years (the upper age limit of 50 years has been selected as there is some evidence that mild cognitive decline begins past this age) • You are in good health • You agree to fast 3 hours prior to testing (only water or herbal tea allowed) (glucose levels are known to modulate performance in several cognitive domains. By having all participants fast for 3 hours prior to testing, we can rule out an enhancing effect of glucose on the cognitive tasks).
Exclusion criteria
• Suffer from cardiac, hepatic, renal, and/or neurological disorders • Have damaged or diseased skin on your face and scalp, or a sensitive scalp • Have a history of alcohol or drug addiction, or severe psychiatric illness • Are receiving drug treatment which may lower seizure threshold (i.e. epilepsy) • Are pregnant • Are sleep deprived (less than 6 hours a day)
Outcome results
None listed