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

• ClinicalTrials.gov Identifier: NCT00981955
• Recruitment Status: Completed
• First Posted: September 22, 2009
• Last Update Posted: July 23, 2010
• Sponsor: Northumbria University
• Information provided by: Northumbria University

Study Description

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.

Condition or disease	Intervention/treatment	Phase
Cognitive Function; Mood	Dietary Supplement: Caffeine and L-theanine	Phase 4

Study Design

• Study Type: Interventional (Clinical Trial)
• Actual Enrollment: 24 participants
• Allocation: Randomized
• Intervention Model: Crossover Assignment
• Masking: Triple (Participant, Investigator, Outcomes Assessor)
• Primary Purpose: Basic Science
• 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.
• Study Start Date: August 2009
• Actual Primary Completion Date: February 2010
• Actual Study Completion Date: February 2010

Arms and Interventions

Arm	Intervention/treatment
Active Comparator: 75mg caffeine	Dietary Supplement: Caffeine and L-theanine; 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.; Other Name: Sun-theanine (l-theanine)
Active Comparator: 50mg l-theanine	Dietary Supplement: Caffeine and L-theanine; 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.; Other Name: Sun-theanine (l-theanine)
Active Comparator: 75mg caffeine and 50mg l-theanine	Dietary Supplement: Caffeine and L-theanine; 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.; Other Name: Sun-theanine (l-theanine)
Placebo Comparator: 0mg caffeine/l-theanine	Dietary Supplement: Caffeine and L-theanine; 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.; Other Name: Sun-theanine (l-theanine)

Outcome Measures

Primary Outcome Measures :

1. Cerebral blood flow [ Time Frame: 0-80 minutes post dose ]
2. Cognitive function [ Time Frame: 0-70 minutes post-dose ]
3. Mood [ Time Frame: 85 minutes post dose ]

Eligibility Criteria

• Ages Eligible for Study: 18 Years to 35 Years (Adult)
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

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

Contacts and Locations

Locations

United Kingdom

Northumbria University

Newcastle upon Tyne, Tyne & Wear, United Kingdom, Ne1 8ST

Sponsors and Collaborators

Northumbria University

Investigators

• Principal Investigator: Crystal Haskell, PhD; Northumbria University

More Information

• Responsible Party: Dr Crystal Haskell, Northumbria University
• ClinicalTrials.gov Identifier: NCT00981955
• Other Study ID Numbers: 25AA1
• First Posted: September 22, 2009
• Last Update Posted: July 23, 2010
• Last Verified: July 2010

Keywords provided by Northumbria University:

Caffeine; Ltheanine; Near Infrared Spectroscopy; Cerebral Blood Flow; Cognitive Function; Mood

Additional relevant MeSH terms:

Caffeine; Central Nervous System Stimulants; Physiological Effects of Drugs; Phosphodiesterase Inhibitors; Enzyme Inhibitors; Molecular Mechanisms of Pharmacological Action; Purinergic P1 Receptor Antagonists; Purinergic Antagonists; Purinergic Agents; Neurotransmitter Agents