Guayusa: The Effect of an Herbal Extract on Alertness and Mental Fatigue

You may not qualify if:

• Unable to understand and/or completely perform the practice test to standard minimum requirements and based on queries performed following the practice test at Visit 1 (Day -7).
• Visual impairments that cannot be corrected with glasses or contact lenses.
• Known intolerance, allergy, or sensitivity to caffeine or any of the other ingredients in the study products and/or any ingredients of the standardized snack provided, including shellfish, egg, fish, gluten, milk, peanuts, soy, tree nuts (coconut and walnut), and gelatin.
• Extreme dietary habits (e.g., intermittent fasting, low carbohydrate diet) that would affect study outcomes as judged by the Principal Investigator.
• Unstable dose of prescription medications (stable is defined as same dose for the past 90 d prior to Visit 1; Day -7).
• Use of prescription drugs (stable or unstable) that have stimulating (e.g., amphetamines \[Adderall® and Dexedrine®\], methylphenidate \[Concerta® and Ritalin®\], diet aids \[such as Didrex®, Bontril®, Preludin®, Fastin®, Adipex P®, Ionomin®, and Meridia®\], containing caffeine or guayusa), cognition boosting, or sedating (e.g., sleeping aids, drugs to treat mental health disorders) effects.
• For females on hormone therapy (including oral contraceptives), the subject must be on a stable dose of hormones (defined as same dose for the past 90 d prior to Visit 1; Day -7).
• Signs or symptoms of an active infection of clinical relevance (e.g., urinary tract or respiratory) within 5 d prior to Visits 2, 3, and 4 (Days 0, 7, and 14). If an infection occurs during the study period, test visits should be rescheduled until all signs and symptoms have resolved (at the discretion of the Principal Investigator) at least 5 d prior to testing, unless the visit will be out of window. If the visit will be out of window, subjects should continue with testing and a protocol deviation will be required.
• Experienced evidence of delirium, confusion, or other disturbances of consciousness to the degree that could affect study outcomes, in the judgement of the Principal Investigator.
• History of learning and/or behavioral disorders such as dyslexia or diagnosed attention deficit hyperactive disorder (ADHD).
• Neurologic disorder that could produce cognitive deterioration including, but not limited to, Alzheimer's disease, Parkinson's disease, stroke, intracranial hemorrhage, local brain lesions including tumors, and normal pressure hydrocephalus.
• History of any infective or inflammatory brain disease, including those of viral, fungal, or syphilitic etiologies.
• History of frequent (≥ 1 occasion/month) migraines that require medication.
• History of repeated minor head injury (e.g., in boxing) or a single injury resulting in a period of unconsciousness for 1 h or more.
• History or presence of clinically uncontrolled important endocrine (including hyperparathyroidism, type 1 or 2 diabetes mellitus and/or hypoglycemia), cardiovascular (including, but not limited to history of myocardial infarction, peripheral arterial disease,), pulmonary (including uncontrolled asthma), hepatic, renal, gastrointestinal, hematologic, immunologic, dermatologic, rheumatic (including gout), and/or biliary, that, in the opinion of the Principal Investigator, could interfere with the interpretation of the study results.
• +10 more criteria