Abstract
BackgroundTo follow up on a recent report from our lab [Hum Psychopharmacol 25:359–367, 2010.] we examined the effects of caffeine on salivary α-amylase (sAA) activity in response to an engaging, non-stressful task in healthy young males (age 18–30 yrs) who consumed caffeine on a daily basis. Using a placebo-controlled, double-blind, between-subjects design, 45 men received either placebo, 200 mg or 400 mg of caffeine (Vivarin®). Participants then rested for 20 minutes, and performed a 20-minute computerized air traffic controller-like task that was cognitively engaging but not stressful. Saliva samples (assayed for sAA and cortisol), blood pressure, and heart rate were taken before (baseline) and 15 minutes after the computerized task.ResultsSystolic and diastolic blood pressure and sAA activity increased across the laboratory session (F’s > 9.20, p’s < 0.05); salivary cortisol levels decreased (F = 16.17, p < 0.05). There were no main effects for caffeine administration on sAA, salivary cortisol, or cardiovascular measures, and caffeine did not interact with the task to alter these measures.ConclusionsLaboratory administered caffeine does not alter sAA activity, even when sAA activity is stimulated by participating in a cognitively engaging task. These data demonstrate that caffeine administration does not affect sAA activity, at least in healthy young men who regularly consume caffeine. Results support recent findings that basal caffeine levels in habitual caffeine users are not associated with basal sAA activity and that daily caffeine intake and diurnal sAA activity are not related.
Highlights
To follow up on a recent report from our lab [Hum Psychopharmacol 25:359–367, 2010.] we examined the effects of caffeine on salivary α-amylase activity in response to an engaging, non-stressful task in healthy young males who consumed caffeine on a daily basis
Blood pressure and heart rate Systolic and diastolic blood pressure increased across the laboratory session such that systolic blood pressure (SBP) and DBP levels did not return to baseline among all participants [F(2,84) > 9.20, p’s < 0.05]
There were no main effects for caffeine administration on SBP, DBP, or heart rate (HR) levels nor did caffeine interact with time to alter these cardiovascular measures
Summary
To follow up on a recent report from our lab [Hum Psychopharmacol 25:359–367, 2010.] we examined the effects of caffeine on salivary α-amylase (sAA) activity in response to an engaging, non-stressful task in healthy young males (age 18–30 yrs) who consumed caffeine on a daily basis. This report is a follow up experiment to our recently published data on the effects of stress and caffeine on salivary alpha amylase (sAA) in healthy young men [1]. We recently reported that caffeine and Caffeine and stress may stimulate sAA activity via SNS activation (for review, see [13]). Caffeine bioavailability may be altered in unanticipated ways as a result of stress exposure on the pharmacokinetic profile of caffeine and its metabolites, though this area needs further investigation (e.g., [14]). Stress in the absence of caffeine results in increased sAA activity (for review see [9]), but the effects of caffeine on sAA activity in the absence of stress are not widely known
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