Cognitive and Cerebral Blood Flow Effects of 2-week Caffeine Abstinence or Maintenance

Behavioural and Cerebral Haemodynamic Effects of Caffeine Withdrawal and Caffeine Administration Following 2-week Maintenance or Abstinence

The purpose of this study is to determine the effects of 2 weeks caffeine abstinence as compared to 2 weeks caffeine maintenance (300mg per day)on cognition and mood. Cerebral blood flow effects will also be assessed in a subset of participants. The role of caffeine abstinence/maintenance in the acute effects of caffeine will also be explored.

The current randomised, placebo-controlled, double-blind, parallel groups study aims to explore the behavioural effects of 2-weeks caffeine abstinence as well as establishing the role of abstinence in the effects of caffeine administration by administering caffeine or placebo to those in a state of chronic and acute abstinence. This research also aims to explore, in a subset of participants, the cerebral blood flow effects of caffeine abstinence and caffeine administration using Near Infrared Spectroscopy (NIRS). Cerebral blood flow will be measured both at rest and during performance of cognitive tasks.

Inclusion Criteria:

• Male/Female
• 18 - 40 years
• Healthy
• Consume ≥ 150 mg caffeine daily
• No herbal supplements/prescription medications (excl. contraceptive pill)
• Non smoker
• Native English speaker

Exclusion Criteria:

• Diagnosis of any significant medical condition or disorder
• Any known allergy or hypersensitivity to food.
• BMI >29.9 or <18.5
• Blood pressure >139/89