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

Cognitive Function Clinical Trial

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.

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00981955
• Other study ID #: 25AA1
• Status: Completed
• Phase: Phase 4
• First received: September 21, 2009
• Last updated: July 22, 2010
• Start date: August 2009
• Est. completion date: February 2010

Study information

• Verified date: July 2010
• Source: Northumbria University
• Contact: n/a
• Is FDA regulated: No
• Health authority: United Kingdom: Research Ethics Committee
• Study type: Interventional

Clinical Trial 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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 24
• Est. completion date: February 2010
• Est. primary completion date: February 2010
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 35 Years

Eligibility

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

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor), Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Cognitive Function
• Mood

Intervention

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.

Locations

Country	Name	City	State
United Kingdom	Northumbria University	Newcastle upon Tyne	Tyne & Wear

Sponsors (1)

Lead Sponsor	Collaborator
Northumbria University

Country where clinical trial is conducted

United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Cerebral blood flow		0-80 minutes post dose	No
Primary	Cognitive function		0-70 minutes post-dose	No
Primary	Mood		85 minutes post dose	No