The Effects of Caffeine and L-theanine Both Alone and in Combination on Cerebral Blood Flow, Cognition and Mood

Study Overview
=================
Brief Summary
-----------------
Although the beneficial effects of caffeine on cognition and mood have been reported in a number of studies, relatively few studies have looked at the effects of caffeine in combination with other phytonutrients despite the fact that caffeine is seldom consumed in isolation. L-theanine is a naturally occurring amino-acid found in tea, and has been used historically as a relaxing agent (Haskell et al., 2008). Few have assessed the impact of l-theanine on cognition, but of those that have, the most interesting results were obtained when l-theanine was assessed in combination with caffeine (Haskell et al., 2008). It remains unclear what is underlying the reported effects. Near Infrared Spectroscopy (NIRS) is an emerging neuroimaging technology that is capable of determining changes in cerebral blood flow (CBF) by measuring the optical properties of oxygenated and deoxygenated blood (Bunce et al., 2006). No study to date has used NIRS to assess cerebral blood flow following treatment with either caffeine, l-theanine or a combination of both. It is anticipated that the proposed study will provide some insight into the mechanism of the previously observed effects both alone and in combination. A randomised, double-blind, placebo controlled, balanced crossover design study will assess the effects of 75mg caffeine, 50mg l-theanine and a 75mg caffeine/50mg l-theanine combination in 24 young healthy adults (18-35). Cognitive and mood assessments will take place at baseline and at 30 minutes following treatment whilst cerebral haemodynamics are measured via the technique of NIRS.

Official Title
-----------------
A Randomised, Double Blind, Placebo-controlled Study to Evaluate the Effects of Caffeine and L-theanine Both Alone and in Combination on Cerebral Blood Flow, Cognition and Mood.

Conditions
-----------------
Cognitive Function, Mood

Intervention / Treatment
-----------------
* Dietary Supplement: Caffeine and L-theanine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Healthy Aged 18-35 Either caffeine consumers (consume more than 150mg caffeine per day) or non-consumers (less than 44mg caffeine per day). Exclusion Criteria: Smoke or consume any tobacco products Not proficient in English language Pregnant (or seeking to become pregnant) Taking recreational, over the counter/prescription medication (including the contraceptive pill), and/or dietary/herbal supplements Have food allergies or sensitivities Have history of/current head trauma, learning difficulties , ADHD, migraines or any gastric problems

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 75mg caffeine<br> | Dietary Supplement: Caffeine and L-theanine<br>* Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.<br>* Other names: Sun-theanine (l-theanine);|
| Active Comparator: 50mg l-theanine<br> | Dietary Supplement: Caffeine and L-theanine<br>* Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.<br>* Other names: Sun-theanine (l-theanine);|
| Active Comparator: 75mg caffeine and 50mg l-theanine<br> | Dietary Supplement: Caffeine and L-theanine<br>* Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.<br>* Other names: Sun-theanine (l-theanine);|
| Placebo Comparator: 0mg caffeine/l-theanine<br> | Dietary Supplement: Caffeine and L-theanine<br>* Acute oral administration of 75mg of caffeine, 50mg l-theanine, 75mg caffeine and 50mg l-theanine in combination or placebo. One dosage administered on each of four separate study days.<br>* Other names: Sun-theanine (l-theanine);|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cerebral blood flow |  | 0-80 minutes post dose | 
| Cognitive function |  | 0-70 minutes post-dose | 
| Mood |  | 85 minutes post dose | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Caffeine, Ltheanine, Near Infrared Spectroscopy, Cerebral Blood Flow, Cognitive Function, Mood