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Effects of Low Doses of Caffeine on Mood, Physiology and Mental Function

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00487227
First Posted: June 18, 2007
Last Update Posted: October 8, 2015
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by:
Northumbria University
  Purpose
It is often assumed that levels of caffeine found in 'decaffeinated' beverages are below any psychopharmacological threshold. However, recent findings indicate that caffeine doses as low as 9 mg may be psychoactive. The effects of caffeine have also been shown up to 6 hours post-administration. The study aimed to establish the lowest active dose of caffeine, and to ascertain the duration of any effects.

Condition Intervention
Healthy Drug: caffeine Drug: Placebo

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Primary Purpose: Basic Science
Official Title: Levels of Caffeine Lower Than Those Found in Decaffeinated Beverages Exert Effects on Cognition, Mood, and Autonomic Activity

Resource links provided by NLM:


Further study details as provided by Northumbria University:

Primary Outcome Measures:
  • Change from baseline speed of attention [ Time Frame: 1 hour ]
  • Change from baseline speed of attention [ Time Frame: 3 hours ]
  • Change from baseline speed of attention [ Time Frame: 6 hours ]
  • Change from baseline speed of attention [ Time Frame: 9 hours ]

Secondary Outcome Measures:
  • Change from baseline accuracy of attention [ Time Frame: 1 hour ]
  • Change from baseline accuracy of attention [ Time Frame: 3 hours ]
  • Change from baseline accuracy of attention [ Time Frame: 6 hours ]
  • Change from baseline accuracy of attention [ Time Frame: 9 hours ]
  • Change from baseline speed of memory [ Time Frame: 1 hour ]
  • Change from baseline speed of memory [ Time Frame: 3 hours ]
  • Change from baseline accuracy of memory [ Time Frame: 6 hours ]
  • Change from baseline accuracy of memory [ Time Frame: 9 hours ]
  • Change from baseline subjective mood [ Time Frame: 1 hour ]
  • Change from baseline subjective mood [ Time Frame: 3 hours ]
  • Change from baseline subjective mood [ Time Frame: 6 hours ]
  • Change from baseline subjective mood [ Time Frame: 9 hours ]
  • Change from baseline blood pressure [ Time Frame: 1 hour ]
  • Change from baseline blood pressure [ Time Frame: 3 hours ]
  • Change from baseline blood pressure [ Time Frame: 6 hours ]
  • Change from baseline blood pressure [ Time Frame: 9 hours ]
  • Change from baseline heart rate [ Time Frame: 1 hour ]
  • Change from baseline heart rate [ Time Frame: 3 hours ]
  • Change from baseline heart rate [ Time Frame: 6 hours ]
  • Change from baseline heart rate [ Time Frame: 9 hours ]
  • Change from baseline salivary caffeine levels [ Time Frame: 1 hour ]
  • Change from baseline salivary caffeine levels [ Time Frame: 3 hours ]
  • Change from baseline salivary caffeine levels [ Time Frame: 6 hours ]
  • Change from baseline salivary caffeine levels [ Time Frame: 9 hours ]

Enrollment: 20
Study Start Date: June 2005
Study Completion Date: November 2005
Arms Assigned Interventions
Placebo Comparator: Placebo Drug: Placebo
Experimental: 2.5mg caffeine Drug: caffeine
Experimental: 5mg caffeine Drug: caffeine
Experimental: 10mg caffeine Drug: caffeine

Detailed Description:
The majority of recent caffeine studies have evaluated doses in the range of 75 - 150 mg or 1 - 2 mg/kg (approximately 130 - 260 ml fresh coffee). Such doses produce well characterised effects; including increased 'alertness', and improvements to measures of reaction time and sustained attention. A previous study has demonstrated improvements to performance following 9 mg caffeine, which represents the lowest known psychoactive dose of caffeine. A number of these effects, including elevated salivary caffeine levels, were still apparent at 6 hours post-caffeine consumption (9). Findings showing effects of 12.5 and 9 mg caffeine are important as these are approaching the levels found in decaffeinated beverages, which are assumed to have no behavioural or physiological effects. However, despite extensive research in this area, the lower threshold for psychoactive effects has not been established. A randomised, placebo-controlled, double-blind, balanced crossover study was undertaken. 20 young men and women (13 female, mean age 20.7 years, standard deviation 2.4) undertook computerised assessments of memory and attention and rated subjective mood. Autonomic activity and salivary caffeine were co-monitored. Assessment took place at baseline, 1, 3, 6, and 9 hours post-administration of placebo, 2.5, 5, and 10 mg caffeine (on separate days) administered in 150 ml fruit juice.
  Eligibility

Information from the National Library of Medicine

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

Inclusion Criteria:

  • native English speaker

Exclusion Criteria:

  • pregnancy
  • medication
  • anaemia
  • heart disorder
  • diabetes
  • respiratory disorder
  • epilepsy
  • asthma
  • panic attacks
  • habitual smoking
  • food allergy
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00487227


Sponsors and Collaborators
Northumbria University
Investigators
Principal Investigator: Andrew Scholey Northumbria University
  More Information

ClinicalTrials.gov Identifier: NCT00487227     History of Changes
Other Study ID Numbers: 7G2CDCH
First Submitted: June 15, 2007
First Posted: June 18, 2007
Last Update Posted: October 8, 2015
Last Verified: October 2015

Keywords provided by Northumbria University:
caffeine
coffee
decaffeinated
cognition
mood
autonomic

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