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| Research article summary (published 29 Sep 2002): |
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Central and peripheral effects of sustained caffeine use: tolerance is incomplete.
Full Abstract
AIMS:
It is widely held that tolerance develops to the effects of sustained caffeine consumption. This study was designed to investigate the effects of chronic, staggered caffeine ingestion on the responses of an acute caffeine challenge, during -euglycaemia.
METHODS:
Twelve healthy volunteers were randomized using a double-blind, cross-over design to take either 200 mg caffeine (C-replete) or placebo (C-naïve) twice daily for 1 week. Following baseline measurements being made, the responses to 200 mg caffeine (blood-pressure, middle cerebral artery velocity, mood and cognitive performance) were examined over the subsequent 120 min. Blood glucose was not allowed to fall below 4.0 mmol l-1.
RESULTS:
After the caffeine challenge, middle cerebral artery blood velocity decreased in both conditions but was greater in the C-naïve condition (-8.0 [-10.0, -6.1] cm s-1 vs -4.9 [-6.8, -2.9] cm s-1 C-replete, P < 0.02). Systolic blood pressure rise was not significantly different in C-naïve, although this rise was more sustained over time (P < 0.04). Mood was adversely affected by regular caffeine consumption with tense aspect of mood significantly higher at baseline in C-replete 11.6 +/- 0.6 C-naïve vs 16.3 +/- 1.6 C-replete, P < 0.01). Cognitive performance was not affected by previous caffeine exposure.
CONCLUSIONS:
Overall these results suggest that tolerance is incomplete with respect to both peripheral or central effects of caffeine.
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Author information
Author/s: Watson, Joanne (J); Deary, Ian (I); Kerr, David (D);
Affiliation: Bournemouth Diabetes and Endocrine Centre, Royal Bournemouth Hospital, Bournemouth, BH7 7DW.
Journal and publication information
Publication Type: Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't
Journal: British journal of clinical pharmacology (Br J Clin Pharmacol), published in England. (Language: eng)
Reference: 2002-Oct; vol 54 (issue 4) : pp 400-6
Dates: Created 2002/10/23; Completed 2003/01/27; Revised 2006/11/15;
PMID: 12392588, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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