None listed
Conditions
Brief summary
Caffeine is readily available and widely consumed by adults of all ages. We are interested in whether temporarily manipulating caffeine levels (from complete washout to a controlled dose of caffeine) has an effect on visual perception in healthy adults. Specifically, we are testing its effect on a contrast judgment task (is one stripey pattern higher in contrast than another?) that our laboratory frequently uses to indirectly measure changes in brain function that occur with normal ageing or in conditions such as migraine. If caffeine indeed influences our test results, then future studies may need to control caffeine consumption.
Interventions
Twenty healthy young (18-35 years) adults will be recruited and screened to ensure healthy eyes and vision. The main task is to observe patterns on a computer monitor and make judgments (by pressing a button) about the contrast of a pattern. There will be two test sessions, a treatment session and control session. The order of the sessions will be randomised and the participants blinded to the treatment. Participants will be instructed not to consume caffeine for 12 hours prior to attending eac
Twenty healthy young (18-35 years) adults will be recruited and screened to ensure healthy eyes and vision. The main task is to observe patterns on a computer monitor and make judgments (by pressing a button) about the contrast of a pattern. There will be two test sessions, a treatment session and control session. The order of the sessions will be randomised and the participants blinded to the treatment. Participants will be instructed not to consume caffeine for 12 hours prior to attending each test session. At the beginning of each test session, participants will undergo baseline visual testing. This will be followed by 1) a controlled dose of caffeine in the form of an over-the-counter caffeine + vitamin pill (2 x ‘No Doz Plus’ tablets = 200 mg caffeine + 20 mg thiamine or Vitamin B1 + 20 mg nicotinic acid or Vitamin B3) or 2) a placebo pill. Visual testing will then occur 45 minutes after tablet ingestion. At the second visit at least one week later, participants will undergo the same protocol (caffeine washout, baseline testing, tablet ingestion, post-tablet testing) such that all participants will have consumed both the caffeine pill and placebo pill. The pills are both white, uncoated, round tablets with no engravings of approximately the same size, which will assist in masking the identity of the pill at each test session.
Sponsors
The University of Melbourne
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 35 Years
Healthy volunteers
Yes
Inclusion criteria
1) Visual acuity at least 6/7.5 in both eyes 2) Good general health
Exclusion criteria
1) Contraindications for No Doz consumption: high blood pressure, recent heart attack, abnormal heart rhythm, stomach ulcer, inflamed colon and small intestine, severe liver disease, seizures, chronic insomnia, moderate to severe kidney impairment 2) Medications with possible interactions with No Doz and/or Vitamin B: tizanidine (muscle relaxant), digoxin (used to treat heart conditions), diuretics (particularly loop diuretics like furosemide), and phenytoin (used to treat epilepsy).
Outcome results
None listed